Soil and Environment

The origin of the catena concept

2012-01-21T21:56:00.007+08:00

The catena concept in soil science comes from the Latin word “catena” which means chain. So it is a chain of soils linked by topography. It also refers to a sequence of soils in different positions in the landscape. It was introduced to the scientific literature by Geoffrey Milne (1898-1942) in a paper entitled “Some suggested units of classification and mapping particularly for East African soils” published in Soil Research-Bodenkundliche Forschung, Supplement to the Proceedings of the International Union of Soil Science Vol. IV No. 3 (1935), pp: 183-198. He noted “the regular repetition of a certain sequence of soil profiles in association with topography” in East Africa which was also observed earlier (in 1911 and 1912) by the German Peter Vageler. Milne wrote that a distinctive word is needed in referring to this phenomenon hence, he proposed the word catena.

Ernst Schlichting (1923-1988) who was professor at the University of Hohenheim in Stuttgart pioneered the approach of considering the soil always as part of the landscape. He proposed that soils in different positions in the catena exchange materials through transport processes and thus could be compared to the transfer processes between horizons in a soil profile. In Schlichting’s view, the genesis of a soil can only be understood if its relation to the other soils in the catena is taken into consideration.

Catena is now also widely used in other sciences particularly ecology albeit with a slightly different meaning (e.g. a catena of terrestrial ecosystems).

(The upper figure shows the linkages between soils in a catena according to Sommer and Schlichting 1997, Geoderma 76: 1-33. The lower figure shows the typical catena in the highlands of Leyte, Philippines).

Hohenheimer Bodenkundliche Hefte: 20 years of publishing original soil research

2011-12-28T22:50:00.011+08:00

The Hohenheimer Bodenkundliche Hefte (ISSN 0942-0754) or Hohenheim Soil Science Book Series will be 20 years old in 2012. Since the release in 1992 of Volume 1 with the title “Stickstoff-Dynamik in Catenen einer erosionsgepraegten Loesslandschaft by G. Lorenz” (Nitrogen dynamics in catenas of an erosion-affected loess landscape), it has already published a hundred volumes of original and relevant soil research. Volume 100 which came out last year (2011), was authored by Shabnam Rathore and carried the title “Assessment of biomass production potential on salt affected land: a soil and terrain database case study (SASOTER) in Badin District, South of Pakistan.”

Published by the renowned Institute of Soil Science and Land Evaluation of the University of Hohenheim in Stuttgart, Germany, this book series publishes dissertations and habilitations carried out at the Institute. During its early years, it was edited by Prof. U. Babel (Soil Biology), Prof. W.R. Fischer (Soil Chemistry), Prof. K. Roth (Soil Physics), and Prof. K. Stahr (Soil Science and Petrography). The present editors are Prof. E Kandeler (Soil Biology), Prof. Y. Kuzyakov (Soil Biogeochemistry), Prof. K. Stahr (Soil Science and Petrography) and Prof. T. Streck (Soil biogeophysics), all internationally well-known soil scientists and authors at the Institute.

In its 20 years of existence, the Hohenheimer Bodenkundliche Hefte has clearly established itself as an important publication in soil science. As can be seen from Google Scholar, many of the titles published in the book series have been cited by papers in various prestigious international journals and books. Vol. 36 on dust deposition of soils in West Africa by Dr. Ludger Herrmann has been the most frequently cited volume of the book series.

World Soil Day

2011-12-06T17:00:00.007+08:00

December 05 of every year is celebrated as World Soil Day by the global community of more than 60,000 soil scientists. According to the official IUSS website, World Soil Day is held on the said date since it is the birthday of H.M. King Bhumibol Adulyadej, The King of Thailand, who has officially sanctioned the event.

As a tribute to the soil as a vital resource, I am posting below a poem written in 2007 by one of my former students at Visayas State University, Juvia P. Sueta. Juvy is now finishing her PhD at the Buesgen Institute, University of Goettingen, Germany.

The Soil Beneath

by Juvia P. Sueta

The soil tells a

fascinating story

of enduring patience

and great beauty.

Out of the hardened rock,

it changes into

an interesting mass

of sand, silt, and clay.

Exposed to the rain, wind

and sunshine, it

grows to maturity.

Time polished it,

throughout all history.

Out of its bosom,

the flowers bloom

and trees grow steadily.

And in its face,

the children play.

Below it;

scholars, artists,

beggars, and poets lay.

Great is the earth,

it cares and nourishes

the whole humanity.

It is nature’s best habitat,

sustaining creatures,

strong or tiny.

It bears witness,

to all that took place

throughout the ages.

It holds the secrets

of past or future events.

it is a treasure chest,

keeping nature’s wealth.

And so nothing compares

to the soil beneath.

The impacts of mining in the Philippines

2011-09-08T22:42:00.008+08:00

Mining is a top and very controversial environmental issue in the Philippines today. It is increasingly becoming a divisive issue too. The government cite economic benefits as sufficient justification to support and encourage mining. In fact, the Intellasia News Online (http://www.intellasia.net) reported on 08 August 2011 that the Philippines' Mines and Geosciences Bureau (MGB) has announced that about 5 million hectares of potentially mineralised areas across the archipelago are now open to local and foreign investors. On the other hand, environmental and religious groups strongly oppose mining because of its well-known negative environmental and health impacts.

A Fact-Finding Team composed of human rights and environmental experts from the United Kingdom which looked into the impact of mining on the environment and peoples' livelihoods in the Philippines highlighted the occurrence of mining-related human rights abuses affecting local communities especially indigenous people; extrajudicial killings of persons protesting against mining; corruption in the mining sector; political pressure on the judiciary resulting in pro-mining decisions; and environmental impacts.

The team observed that "the record of mining companies with regard to environmental protection, disasters and post-mining clean-up in the Philippines is widely acknowledged, even with the government, to be very poor. As of 2003, there had been at least 16 serious tailing dam failures in the preceding 20 years and about 800 abandoned mine sites have not been cleaned up. Clean-up costs are estimated in billions of dollars and damage will never be fully reversed."

It warned that "water contamination from mining poses one of the top three ecological security threats in the world. Many mining applications in the Philippines are in water catchment areas close to the sea, and pose major threat to valuable marine resources." The severe pollution of the Taft river system in Eastern Samar as a result of the mining activities in Bagacay is a vivid example (please see related article in this blog).

The report also emphasized the very high geo-hazard risks in the Philippines. "In the Philippines, over half of the active mining concessions and two-thirds of exploratory concessions are located in areas of high seismic risk where earthquakes are likely."

"The Philippines is considered as the hottest hotspot in the world in terms of threats to its mega diverse biodiversity. Thus there is an urgent need to properly manage its natural resources. It is estimated that 37% of Philippine forests may be exposed to new mining."

Should universities campaign for or against mining?

Some leading state universities in the Philippines are reportedly being pressured by environmental and religious groups to take an “official” anti-mining stand. Universities may take lead in promoting responsible mining and in fact should conduct relevant scientific investigations to prevent or minimize the impacts of mining on the environment and people. But universities should not take an anti or a pro mining stand. They should remain neutral and allow their constituents (the researchers and scientists) to evaluate facts and decide for themselves what stand to take about mining. A university should strive to seek the truth. Always.

Reference:

Doyle C, Wicks C, and Nally F. 2007. Mining in the Philippines: Concerns and Conflicts. Report of a Fact-Finding mission to the Philippines. Society of St. Columban, West Midlands, UK, 63pp.

Jackfruit is suitable for Leyte and Samar islands

2011-08-14T08:53:00.007+08:00

Jackfruit (Artocarpus heterophyllus) is now an important crop in Leyte and Samar islands or Eastern Visayas (Region 8) in the Philippines. In fact, the Department of Agriculture (Region 8) and the Visayas Consortium for Agriculture and Resources Program (ViCARP) based at VSU have made it a priority crop for the region. Consequently, more studies are now being conducted by research centers and universities to improve jackfruit productivity and to develop jackfruit-based food products.

A research funded by the Bureau of Agricultural Research (Manila) from 2000 to 2003 titled "Characterizing biophysical environments for research prioritization and agricultural production in Region 8 (VB Asio, BB Dargantes, PP Garcia, K Israel)" produced the first solid scientific evidence that jackfruit is generally suitable for the region based on climate, geology, topography, land use, and soil factors. Among the significant outputs of this research were the suitability maps developed using GIS for jackfruit, rambutan, mango, abaca, coconut, sweetpotato and cassava which were distributed to all government agencies in the region starting 2004.

The suitability maps and other highlights of the research were also presented during the First Regional Fruit Congress in Tacloban City in 2003 which was attended by researchers, agricultural technicians, farmers, and policymakers. It was agreed at this congress to give priority to jackfruit and not mango which was found generally unsuitable for most parts of the region (except the northwestern side of Leyte whose climatic, geologic and soil characteristics are closely similar to those of the nearby Cebu island).

(The land suitability map for jackfruit shown was the first draft version we developed in 2002. Photo of jackfruit tree was taken from www.backpackingmalaysia.com)

Reference:

Asio VB, BB Dargantes, PP Garcia and K Israel. 2004. Characterizing biophysical environments for research prioritization and agricultural production in Region 8 (Leyte-Samar). Terminal Report, LSU-DA-BAR GIS Project.

Methane emission from rice fields

2011-07-21T11:12:00.003+08:00

Methane (CH4) and carbon dioxide (CO2) are the end products of carbon decomposition in rice fields and other wetlands. Methane, a major greenhouse gas, is the terminal step of the anaerobic breakdown of organic matter in wetland soils. It is exclusively produced by methanogenic bacteria that can metabolize only in the absence of free oxygen and at redox potentials below -150 mV (Neue et al. 1997).

According to the above-cited paper by Dr.H.U. Neue (former Head of the Soils Department at IRRI and later Professor of Soil Chemistry at the University of Halle-Wittenberg, Germany) one of the pioneers in methane research in rice fields, methane is largely produced by transmethylation of acetic acid and to some extent, by the reduction of carbon dioxide in wetland soils.

The rate and pattern of organic matter addition and decomposition also contribute to the rate and pattern of methane production. In rice field, methane production generally increases during the cropping season. Easily degradable soil carbon, plant litter, root exudates, decomposing roots and aquatic biomass that are added to the anaerobic zone of the paddy soil (this is the zone below the thin oxidized or brown soil surface) are the major carbon sources for methane production.

Presently, there is widespread research interest in the development of methods and strategies to reduce methane emission from rice fields and other wetlands. Some early studies have shown that sodium chloride at high concentration inhibits methane formation. Addition of sea water has also been found to inhibit methane formation at low salt concentration because of its sulfate content. Very recently, Dr. Roel R. Suralta and colleagues at Philrice, Nueva Ecija, have demonstrated that iron fertilizer application significantly reduced methane emission from rice field. More importantly, the iron fertilizer application also increased rice yield (Suralta et al., 2011).

References

Neue HU, JL Gaunt, ZP Wang, P Becker-Heidmann, and C Quijano. 1997. Carbon in tropical wetlands. Geoderma 79: 163-185.

Suralta RR, FS Gorospe, CA Asis Jr and K Inubushi. 2011. Effect of iron fertilizer application on the yield and methane emission of paddy rice field. In: Proceedings of the 14th Annual Meeting and Scientific Conference, Philippine Society of Soil Science and Technology (PSSST), VSU, Baybay, Leyte 25-27 May 2011, pp:95-96

Report on the 14th PSSST Scientific Conference held at VSU, Baybay, Leyte

2011-05-28T20:14:00.012+08:00

The 14th Annual Meeting and Scientific Conference of the Philippine Society of Soil Science and Technology (PSSST) was held at the Visayas State University (VSU) in Baybay City, Leyte last 25-27 May 2011. About 140 soil scientists, soil practitioners, and agriculturists working in universities, government agencies, non-government organizations, and private companies throughout the country attended the conference.

The opening program was graced by Dr. Florentino Tesoro who represented Congressman Angelo B. Palmones (AGHAM Partylist), Dr. Jose L. Bacusmo (VSU President), Prof. K. Stahr (Germany), Mr. Deogracias Pernites (representing Mayor Carmen Cari of Baybay City), Dr. Cezar Mamaril (PSSST Adviser), Dr. Eduardo Paningbatan (PSSST Adviser), Ms. Constancia Mangao (PSSST President) and Dr. Victor B. Asio (Dean of the College of Agriculture, VSU).

Prof. Dr. Karl Stahr, the Chairman of Division I of the International Union of Soil Sciences (IUSS), gave the keynote lecture about the limestone soils in Southeast Asia particularly Thailand, Vietnam, and Laos. Dr. Gamini Keerthisinghe of the Australian Centre for International Agricultural Research (ACIAR) gave a plenary paper on challenges to sustainable crop production.

A total of 26 oral papers were presented dealing with various soil topics ranging from fertilization to soil characterization and geospatial modeling. In addition, 25 poster papers were presented. The presenters of the best oral and poster papers were awarded with certificates and cash.

In the afternoon of the last day of the conference, a post-conference tour was organized and sponsored by the Department of Agronomy and Soil Science of VSU to Lake Danao located at 630 m ASL in the central highlands of Leyte. On the way to the lake, the participants were able to see the following: 1) the City of Ormoc; 2) the mouth and headwater of Anilao River which caused the tragic flooding of Ormoc City in 1991 killing 8,000 people; 3) the volcanic landscape which was traditionally used for large-scale sugarcane production; 4) the 1,912 ha Lake Danao along the Philippine Fault Line; 5) an Andisol soil profile (Typic Hapludand); and 6) the Tongonan Geothermal Plant, one of the largest in Asia.

Overall, the conference was a great success. The attendance of Prof. Stahr from the University of Hohenheim in Germany and Dr. Keerthisinghe from ACIAR in Australia gave the conference an international standing especially since Prof. Stahr represented the IUSS of which PSSST is a member.

The Department of Agronomy and Soil Science of VSU which co-hosted the conference, is grateful to the VSU president for the encouragement and support, and the officers and advisers particularly Dr. Cezar Mamaril of PSSST for bringing the conference to VSU.

(All photos were taken by Glenn Largo)

Soil Science is also called pedology

2011-05-09T23:54:00.002+08:00

In American soil science, pedology (pedo is Greek for ground or soil) has recently been made as a subdiscipline that deals with soil morphology, genesis and classification. In other parts of the world, however, particularly in non-English speaking countries in Europe, Asia and Africa soil science has remained synonymous to pedology (Bech, 2006). Historically, pedology was the original term for the scientific study of the soil introduced by Fallou and it was only in 1924 during the planning for the first international congress that the term soil science was introduced as a synonym. This was in fact reflected in the paper that Glinka presented during the congress (Glinka, 1927).

Until today many textbooks, scientific journals and academic departments dealing with soil science in non-English speaking countries bear the name pedology. In 2002, there was an internet debate among some members of the International Union of Soil Sciences (IUSS) about the term pedology. While many North Americans who joined the debate strongly argued for the use of pedology as a branch of soil science, most soil scientists from Europe (e.g. the world-reknown R. Dudal from Belgium) and other parts of the world maintained that pedology is synonymous to soil science and is not a subdiscipline. Because of the disagreement, pedology was not used as a subdiscipline in the IUSS,

The traditional branches of soil science include soil chemistry, soil biology and biochemistry, soil physics, soil mineralogy, soil genesis, survey and classification, soil conservation, and soil fertility. Many soil scientists at present are experts of new emerging fields of soil science like hydropedology (interaction between hydrosphere and pedosphere), landscape pedology (role of soil in landscape processes), ecopedology (role of soil in terrestrial ecosystems), soil biogeochemistry (how biological and geochemical processes in soils affect element cycle), pedometrics (use of mathematical and statistical tools to interpret and analyze soil data), soil geography (local, regional and global distribution of soils), soil protection, and soil science history.

References
Bech, J. 2006. Eupedology: a solution to a controversy. IUSS Bulletin 109: 27-30.
Glinka, K.D. 1927. Dokuchaiev’s ideas in the development of pedology and cognate sciences. Trans. First Intern Congr. Soil Sci., Wisconsin, vol. 1, pp: 116-135

Leading Soil Scientist is Keynote Speaker of the 14th PSSST Conference in May 2011

2011-03-03T22:19:00.005+08:00

Prof. Dr. KARL STAHR, Chairman of Division I (Soil in Space and Time) of the International Union of Soil Sciences (IUSS), the global association of soil scientists, has accepted our invitation to be the Keynote Speaker of the 14th PSSST Scientific Conference on 25-27 May 2011 at VSU, Baybay, Leyte, Philippines.

Prof. Stahr gained his doctorate from the Technical University Stuttgart, Germany, in 1972 and his Habilitation (highest academic qualification required to become a professor in Germany and several other European countries) in Soil Science at the University of Freiburg in 1979. Since 1988 he is Professor of Soil Science and Petrography at the Institute of Soil Science and Land Evaluation, University of Hohenheim, Stuttgart. His main fields of research are: soil genesis, soil mineralogy, land evaluation, N-cycle, and recycling of organic waste. He has conducted research projects dealing with forest and agricultural soils of Germany as well as Brazil, Ecuador, Argentina, Spain, Portugal, Egypt, Israel, Turkey, PR China, Somalia, Niger, Benin, Vietnam, Thailand, and Philippines.

Prof. Stahr has been actively involved in a wide range of professional activities serving as: Vice Chairman (1979-1981, 1985-1989) and Chairman (1989-1995) of Commission VII of the German Soil Science Society, Vice Chairman of Commission VII of the International Soil Science Society (1986-1998), and President of the German Soil Science Society from 1998 to 2001. He has organized several national and international workshops, excursions and congresses.He has been elected member of many University boards since 1967 such as Dean of the Faculty of Landscape Planning, Technical University of Berlin (1987/88), Dean of the Faculty of Plant Production and Landscape Ecology, University of Hohenheim (2000-2002) and as Vice Dean of the same faculty since 2002. He also serves as Chairman of the special research project "Uplands Program 564" of the University of Hohenheim since 2005.

He has authored and co-authored hundreds of papers which appeared in prestigious peer-reviewed international journals as well as several influential textbooks in soil science (in German). He is in the Editorial Boards of Catena, Plant Nutrition and Soil Science, Geoderma, Trends in Soil Science, and Hohenheimer Bodenkundliche Hefte.

Prof. Stahr has supervised close to a hundred PhD students from many countries around the world.

National Conference of the Philippine Society of Soil Science to be held in May 2011

2011-02-06T02:13:00.003+08:00

The Philippine Society of Soil Science and Technology Inc (PSSST) will hold its 14th Annual Meeting and Scientific Conference on 25-27 May 2011 at the beautiful campus of the Visayas State University (VSU) in Baybay, Leyte, Philippines.

Theme of this year's conference is Improving the Productivity of Marginal Lands Through Integrated Soil and Water Management. Marginal lands particularly degraded uplands are widespread throughout the country and improving their productivity is vital to attaining food security.

More than a hundred soil scientists from various universities, government agencies, private companies and non-government organizations are expected to attend the three-day conference. In addition, some leading soil scientists from Australia, Canada, and Germany will be attending as plenary speakers.

The Department of Agronomy and Soil Science of VSU, a co-sponsor of the conference, will be organizing a pre-conference tour for those participants who will arrive early. The tour will enable the participants to observe the major soils in the central highlands of Leyte.

VSU can be reached via Ormoc City and Tacloban City. It takes about 30 minutes by car to reach VSU from Ormoc City and two hours from Tacloban City.

A comparison of organic and conventional farming

2010-12-19T12:08:00.003+08:00

The Council for Agricultural Science and Technology (CAST) in the USA, assembled in 1980 a high-powered Task Force composed of 24 scientists (chaired by S.R. Aldrich) with expertise in agricultural economics, agronomy, animal science, dairy science, entomology, food science, horticulture, soil science, veterinary medicine and others to look into the similarities and differences between organic and conventional farming. The Task Force report, which remains very relevant to the current debate surrounding organic and conventional agriculture, was officially published as CAST Report No. 84 "Organic and Conventional Farming Compared" in October 1980.

Some of the interesting highlights of the report are:

1. Conventional and organic farming have much in common. They differ principally in the use of modern chemical technology. Conventional farmers use commercial inputs (fertilizers, pesticides, animal feed additives) to increase productivity while organic farmers prefer to use natural resources.

2.Both conventional and organic farmers use various mechanical, biological and other means to control pests. Conventional farmers use synthetic pesticides but organic farmers prefer to avoid them.

3. Conventional farmers extensively use nutritional supplements in animal feeds, hormonally active substances, and drugs. These substances are generally unacceptable to organic farmers.

4. The terms "natural" and "organic" are often used interchangeably in organic farming. But in science, organic refers to carbon compounds. Many such compounds occur in nature and many are synthesized in laboratories and factories. Likewise, many inorganic or noninorganic compounds occur naturally. Hence, natural compounds are not necessarily organic, and organic compounds are not necessarily natural.

5. Urea is a natural organic waste product of human and animal metabolism. It is present in animal and human excreta and is therefore accepted as a natural and nonartificial nitrogen source in organic farming. However, the urea that is synthesized in factories which is chemically identical to the urea produced by human and animal metabolism (used as fertilizer in conventional farming), is not acceptable in organic farming. This is one of the inconsistencies of organic agriculture.

6. The urea produced by animals (present in excreta) or by factories (in commercial fertilizers) is transformed in the soil into ammonium and nitrate ions, the important forms of nitrogen taken up by plants. Both ions are inorganic, not organic. Therefore, in scientific terminology, the organically grown food produced with urea derived from animals is actually "inorganically grown."

7. The "organic foods" produced by organic farming are composed of chemicals. Most foods contain many chemicals, and most of these are organic chemicals, whether the foods are produced by conventional farming or organic farming.

Favorite and influential soil science books

2010-12-17T20:41:00.005+08:00

Below is my short article which appeared in the IUSS Bulletin 117 (Nov 2010) and 118 (June 2011) under the title "Favorite Soil Science Books."

Soil science is a rapidly growing ecological earth science. Consequently, the number of books on the subject has greatly increased in the last two decades. So to choose my top three soil science books, I thought of this criterion: the book must have been very useful to me when I was a student and it is still useful now in my research and teaching activities as a professor of soil science. The criterion automatically disqualifies some very good books that I used as a student but for various reasons I seldom or do not use them today as well as some outstanding soil science books published in recent years but were not yet available during my student days.

My first choice is the Properties and Management of Soils in the Tropics by Pedro A. Sanchez published in 1976 by John Wiley and Sons. It discusses in a simple but in-depth manner the tropical environment (climate, vegetation types, geology, land use and farming systems); the classification of tropical soils using Soil Taxonomy, FAO and some other important systems; the physical and chemical properties, clay mineralogy, and exchange processes of tropical soils; soil acidity and liming; soil nutrients and fertility evaluations; and soil management under different tropical land use systems. This outstanding book certainly belongs to the most important and influential books on tropical soils. I still use it regularly and even require my graduate students to read certain parts of it.

My second choice is Tropical Soils. A Comprehensive Study of their Genesis by E.C.J. Mohr, F.A. van Baren, and J. van Schuylenborgh (3rd revised edition) published in 1972 by Mouton-Ichtiar Baru-Van Hoeve. The book has three parts. Part I deals on the fundamentals of climate, rock and mineral weathering, and organic matter transformation. Part II discusses oxisols, leteritic soils, podzolic soils and podzols, vertisols, paddy soils, and andosols. Part III covers the experimental and physico-chemical study of soil-forming processes. I find it an excellent and unique book on tropical soils because of the coverage and details in which the topics are presented. It has been very useful to me especially during my masteral and doctoral studies (we used it for the course on tropical soils in Hohenheim). I still consult this book often which is an important part of my personal library.

My third choice is the standard soil science textbook in German-speaking countries, the Scheffer/Schachtschabel Lehrbuch der Bodenkunde (Textbook of Soil Science) now in its 16th edition (Spektrum Academisches Verlag). The book has undergone several revisions under different teams of authors. The latest edition was prepared by H.P. Blume, G.W. Bruemmer, R. Horn, E, Kandeler, I. Koegel-Knabner, R. Kretzschmar, K. Stahr, and B.M. Wilke, all leading soil scientists. It covers the origin and development of soils; physical, biological and chemical properties of and processes in soils; nutrients and contaminants; soil systematics and geography; soils and soil landscapes of Europe and the world; soil evaluation and protection. It is an excellent textbook for students who understand German. I find it also a vital reference for my research and teaching activities.

Biocalcification: the biological accumulation of CaCO3 in rice soils

2010-10-24T22:20:00.009+08:00

Lowland rice cultivation can enhance the proliferation of snails resulting in the accumulation of calcium carbonate (CaCO3) in the topsoil. Frank Moormann and Nico Van Breemen, well-known Dutch pedologists, first observed this phenomenon in Central Luzon, Philippines, while visiting the experimental sites of the International Rice Research Institute in the 1970s. H.U. Neue, head of the Soils Department of IRRI at the time, encouraged this writer to investigate the phenomenon. Our research revealed that such biological accumulation of CaCO3 which we named biocalcification, occurs in several rainfed and irrigated rice-growing areas in the Philippines (Asio, 1987; Asio and Badayos, 1998).

The figure below shows the proposed generalized model of biocalcification in rice fields. It consists of two stages. Stage 1 is on the proliferation of snails which is generally dependent upon the calcium content of the soil or irrigation water. Moormann et al. (1976) suggested that calcium, of which some is present in the irrigation water as Ca(HCO3)2, is taken up by the snails and transformed into shells which in turn form the source of the free CaCO3 present in the soil surface. Thus, calcium-rich irrigation waters favor snail proliferation in soils regardless of calcium content and origin. On the other hand, calicum-poor irrigation waters would only promote snail abundance if the soils are rich in calcium like those formed from basic parent materials. In rainfed areas,bunding soils rich in calcium could also enhance snails proilferation or from direct transport of shells from irrigation ditches.

Stage II starts with the accumulation of shells. Dissolution of shells in water normally takes years (CaCO3 is slowly soluble in pure water) particularly in non-acid soils. But in rice soils chemical dissolution of the shells is enahnced by the carbonic acid formed by the reaction between carbon dioxide coming from organic matter decomposition, and water. Moreover, the physical disintegration of the shells is hastened by alternate dry and wet condition which commonly occurs in rice fields, and by field operations particularly puddling. The end result is the accumulation of free CaCO3 and the rise of pH in the soil surface. This condition in turn promotes the proliferation of snails.

Among the soil fertility effects of biocalcification include an increase in the availability of calcium and magnesium but a decrease in the availability of phosphorus and zinc to the rice plant.

References

Asio VB. 1987. Biocalcification and siltation in paddy soils. MSc thesis, UP Los Banos/International Rice Research Institute, Laguna.

Asio VB and Badayos RB. 1998. Biological accumulation of calcium carbonate in some lowland rice soils in the Philippines. The Philippine Agriculturist 81: 176-181.

Moormann FR, Tinsley RL and Van Breemen N. 1976. Notes on a visit to multiple cropping project in Pangasinan. Mimeographed papers (unpublished), IRRI, Laguna, 4pp.

Challenges and opportunities in agriculture

2010-10-11T19:41:00.005+08:00

by Dr. Cezar P. Mamaril
Senior Consulting Expert of Philippine Rice Research Institute (PhilRice)

Los Baños, Laguna

I would like to share my thoughts about current challenges and opportunities in agriculture that institutions like Visayas State University (VSU) should be concerned. I could not over emphasize the fact that we are facing the problem of producing sufficient food to feed the ever increasing population of our country. Last census reported that our population is increasing by 2.3 percent, while our food production (particularly rice) is increasing by about 2.5 percent. The minimal growth difference between population and food production is not sufficient to provide the other requirements of small farmers to live a decent life. I hope the current census will show a decline in population growth so that we will have a better breathing space. (If you have not yet been interviewed by the census takers, you better do so otherwise you may not get your ration of rice!). Furthermore, some recent reports show that the per capita rice consumption in the Philippines has been increasing from less than 100 kg/year several years ago to almost 120 kg/year currently which suggest that some people can not afford to purchase other kinds of food besides rice. Yet in developed countries like Japan and Korea, the per capita consumption is decreasing with increasing income. I was told by my younger son who is an Agric. Economist that the Philippines is now the largest rice importer in the world. I read in the newspaper that this year alone, the government will be importing 2.45 million tons of rice. Is this a sign that Filipinos are retrogressing economically while our Asian neighbors are moving forward?

Besides inadequate food production, lands suitable for the expansion of food production is declining fast suggesting that time will come when we can no longer increase food production by expansion of area. Likewise, there is also the problem of conversion of agricultural lands for other human activities such as real estate housing projects, industrial activities, game parks like golf courses, etc. It is also unfortunate that most of these areas being converted into other human activities are productive lands mostly irrigated lowland rice areas. Since land is a finite resource, we should properly and efficiently utilize it.

Population also creates pressure on water resources which is quite critical especially in rice growing areas. Forests are also subjected to tremendous pressure with increasing population because of the demand for building materials and for fuel. With increasing deforestation, water resources will also diminish. Likewise, when water resources decrease, the share for agriculture for water will also decrease while domestic and urban needs increase because of increasing population. Thus, food production will be greatly affected especially for lowland rice and could lead to lower yields. It has been observed that not only the surface water resources that is affected by deforestation but also the ground water level. It is doubly serious especially in coastal areas because as the fresh ground water table gets deeper, sea water intrusion takes place to replenish the fresh ground water. Subsequently when ground water which is contaminated with sea water is pumped for irrigation the soil may become saline which is adverse to crops production.

The challenge therefore is how one can proceed to produce sufficient food for an unabated population growth with less land and declining soil productivity and less water resources and climate change. The current scenario looks bleak but we should remain optimistic and be challenged and remain hopeful for Divine intervention. We should put our efforts and minds together to use effectively and efficiently whatever resources are available.

Currently there are technologies being disseminated which are not cost effective because they are highly generalized rather than site specific. Thus most often farmers do not realize the benefits that are claimed to be obtained through these technologies. You may also agree with me that there is no “perfect” or “universal” technology that is appropriate for all sites and conditions. Technologies being generated should define the site characteristics and conditions where such technology is effective. Certain technologies are being disseminated prematurely; i.e. not extensively tested before being released for dissemination under all conditions and crops. What is effective for one crop is not necessarily true for all crops. A more specific example is technologies suitable for upland rice is not necessarily appropriate for irrigated or rainfed lowland rice and yet they are the same crop. A friendly advice to researchers is to define and characterize your experimental sites thoroughly so when you finally will disseminate your findings, you can specify where such technology works or where it does not.

In preparing research programs, it might be wise to involve the different stakeholders, such as the farmers and providers of farm inputs, to insure that there is relevance to the stakeholders’ need and capability and for the eventual adoption of whatever results generated by research. As researchers we often feel that we have better ideas than the farmers to resolve their problems and yet while research results might seem encouraging, farmers are hesitant to adopt these due to other factors that the research failed to consider during the process of conducting the study. I can cite several examples. A technology may produce successfully high yields but it requires high cost of inputs, both materials and manpower, which some farmers does not have the capacity to obtain the inputs. Naturally it is likely that many farmers will not adopt such technology. It might be a good idea to generate a cafeteria of technologies that require different levels of inputs and capabilities from which farmers can choose depending on their financial and technical capacities. Thus, socio-economic characterization of target stakeholders is imperative besides biophysicochemical characterization of the target areas.

There are rice areas where once farmers can grow two seasons of rice a year with reasonable yield but because of declining supply of water resources, the dry season rice crop often fails. Under such situation, crop diversification may be considered wherein during the dry season other crops should be planted. In choosing the alternative crop, however, the crop being introduced should have an economic value equal or better than rice if possible. Crop diversification will also enhance soil productivity. In a rolling landscape, it is possible that the bottom portion of the toposequence will be planted to rice while those in the top and slope portion to upland crops. Integrated crop diversification will likewise reduce economic risks on the part of the farmer.

With increasing cost of farm inputs, we should assist the farmers to utilize these external inputs effectively and efficiently as well as the proper utilization of farm biomass. One reason why chemical fertilizers are claimed to cause soil degradation is because of misuse rather than overuse of fertilizers which could lead to nutrient imbalance. There is increasing evidence of widespread multi nutrient deficiencies in our country especially in areas where crops are constantly applied with chemical fertilizers like rice, corn and sugarcane. This is because most often than not, only NPK fertilizers are applied and in the meantime the native supply of the other essential nutrients are being depleted. It is imperative that proper diagnosis of the nutrient status of soils should be regularly undertaken so that only the limiting nutrient should be applied in proper proportion to the other essential nutrients. Unfortunately the cost of soil analysis is beyond the reach of small farmers plus the fact that there are limited and inaccessible soil laboratories in the country. Therefore, there is a need to develop cheap and simple techniques to diagnose nutrient status of soils. Currently, the available simple diagnostic tools being promoted are the Soil Test Kit (STK), Nutrient Manager, a computer assisted method developed by IRRI, and the Minus One Element Technique (MOET) kit which is designed primarily for lowland rice soils.

Integrated nutrient management strategy may also reduce the cost of external input use especially if one will fully and efficiently utilized farm produced biomass as supplemental source of nutrients. Utilization of on farm biomass should not require special handling of the materials to the extent that additional time and facilities are required for the farmer to process these materials before such can be applied to the soil. Farmers usually are apprehensive to do extra efforts especially if the additional benefit will not significantly compensate the extra effort spent. More efficient and effective ways to utilize these on farm biomass has to be developed rather than the traditional composting and inoculating with decomposing or mineralizing organisms. There should be some means to stimulate the indigenous and heterogeneous soil organisms to decompose and mineralize organic materials rather than utilizing isolated pure strains of organism which will be an added cost to the farmer.

There must be many more opportunities that could enhance agricultural production and help uplift the well being of farmers but I leave them for you to think about. I would like to point out, however that based from my own farm experience, increasing production does not necessarily lead to better livelihood for a small farmer mainly because under our present situation, the middlemen or traders usually earn more than the farmers. Marketing is an important problem that small farmers face. Unless small farmers are organized to be able to dictate the price of their produce, they will never improve their lot. Unfortunately farmers’ cooperative movements in our country do not have a commendable history. These should be one area of interest that the new government should look into. Coincidentally, while preparing my talk, I heard in the radio last Wednesday, that one of the advocacies that the new Secretary of Agriculture Alcala has proposed to President Aquino during his interview for the DA position which impressed the President is the elimination of middlemen by providing opportunities for small farmers to sell their produce directly to the consumers. It will be interesting to see what plans, programs and strategies our new government will pursue to enhanced the well being of our small farmers and fisher folks.

In closing I would like to reiterate that we should remain optimistic that the seemingly bleak scenario of our agricultural sector mentioned earlier can be overcome if we put our acts together and with the guidance of our Almighty God. Moreover, I would like to leave the following quotation from Henry David Thoreau “If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet a success unexpected in common hours.” Success in any endeavor could be attained through perseverance, determination and hard work.

----------------
*Excerpt of keynote speech delivered during the College of Agriculture Day, Visayas State University, Baybay, Leyte on July 2, 2010.

*Dr. Mamaril is a retired UP Los Banos soil science professor and International Rice Research Institute (IRRI) scientist. He is the son of Mr. Julian Mamaril, the first Superintendent of Visayas Agricultural College (forerunner of Visayas State University) in the early 1960s.

Global warming and our local environmental problems

2010-10-10T22:15:00.008+08:00

Global warming is the increase in the average global temperature. It is a real problem now and we are starting to experience its bad effects like the more frequent occurrence of strong typhoons, the warming of sea water resulting in decreased fish catch by fishermen, and the increased amount of rainfall resulting in catastrophic floods and landslides. It is predicted that the tropics where the Philippines is located will be most affected by global warming.

But apart from this global environmental problem, there are also serious local environmental problems that need urgent action. These include deforestation, land degradation, and soil and water pollution. Except for deforestation, these local problems have seldom grabbed the headlines and the endorsement of politicians and popular personalities hence most people are not well aware about the severity of these problems. But they are already threatening our lives and studies have indicated that these environmental problems may have already contributed to the loss of lives or have caused health problems of people.

The fact that much of the original or primary forest in most Philippine islands is now gone clearly indicates that we failed in protecting this vital natural resource. No need to cry over spilt milk says the popular expression. What we need to do is to see to it that the forest that remains is protected and the degraded uplands, the product of deforestation and kaingin in previous decades, are rehabilitated especially in critical watersheds across the country. A degraded land has reduced capacity to absorb rain so that much of the water during rainy days flows on the land surface resulting in floods and lowering of the water table (meaning, drying up of wells!). Degraded lands are also infertile and unproductive and thus are a threat to food security. Many of the poorest farmers are also living and farming in these marginal lands.

Soil and water pollution is largely caused by improper disposal of municipal solid wastes, the unregulated use of pesticides and fertilizers by farmers, and mining. Most towns in the country do not have proper dumpsites. Very disturbing is the fact that many municipalities use their mangrove areas (a vital breeding place for marine organisms) as dumpsites for solid municipal wastes. The unregulated use of pesticides and fertilizers by farmers also leads to soil and water pollution. You can easily notice this from the unusual vigorous growth of algae and aquatic plants around rice fields, ponds, rivers and bays suggesting excess amount of nutrients from fertilizers and other sources. Mining is also a major cause of soil and water pollution. It is very unfortunate that more and more areas are opened to mining. The negative environmental effects of the Bagacay Mine which operated from 1954 to 1992 are still there. Recent major efforts to rehabilitate the site have not been successful.

One last thing: when you drink a glass of water, how do you know that it is not yet contaminated with harmful chemicals?

Photo source:
The global warming figure above was taken from the Renewable Energy Blog
http://www.solarpowerwindenergy.org

Earthworms: the most important soil and ecosystem engineers

2010-08-29T12:48:00.007+08:00

Earthworms are thought to be the most ancient soil animals having started colonizing terrestrial environments about 600 million years ago (Spain and Lavelle 2001). They are the most predominant soil fauna except in dry and cold climates. Earthworms are semiaquatic animals which extract water continuously from the surrounding soil inorder to maintain their cuticle in a moist state to facilitate gas exchange. Thus moisture status is a major limitation to earthworm activities and distribution.

Spain and Lavelle (2001) reported that since earthworms live in direct and continuous contact with the soil matrix and the soil solution, their presistence, propagation and activity are greatly affected by the chemical (pH, dissolved ions) characteristics of the soil. Based on their sensitivity to soil pH, earthworms are grouped into acidophilic species (able to thrive below pH 6 such as in organic forest litter), neutrophilic species (they prefer soil pH 6 to 7) and basophilic species (prefer basic soils).

Three ecological types of earthworms (Spain and Lavelle, 2001)

a) Epigeics. Earthworm of this type live in the litter layers and thus are effective compost-makers. However, they have no or little effects on soil structure.

b) Anecics. These are earthworms that feed on the surface littler that they mixe with soil but spend most of the time in galleries they create within the soil. They are
also able to translocate considerable amount of leaf-litter into the soil.

c) Endogeics. Earthworms of this type live and feed within the soil. Among the earthworm types, the endogeics are the major agent of soil aggregation.

Effects of earthworms on soil properties

Earthworm burrows are known to have high continuity in both horizontal and vertical directions and thus greatly influences water and air movement in the soil. Earthworms influence the physical and chemical soil properties in many ways by burrowing, casting, feeding and propagating. According to Emmerling et al. (2002) earthworms are the most important ecosystem engineers (organisms that may modify or create their habitat and thus influence availability of resources to other species and soil properties) in arable soil due to their lasting effects on soil physical and biochemical properties.

In an interesting laboratory study to assess the impact of ecologically different earthworm species on soil water characteristics, such as soil tension, water content, and water infiltration rate, Ernst et al. (2009) exposed three earthworm species (Lumbricus rubellus, Aporrectodea caliginosa, Lumbricus terrestris) in soil columns (diameter 30 cm, height 50 cm) for 100 days with a total fresh earthworm biomass of 22.7 ± 0.4 g per column, each in duplicate. Each column was added with 30 g of sieved and rewetted horse manure placed on the soil surface as a food source. Precipitation events (10 mm) were simulated at day 28 and day 64.

Results revealed that ecologically different earthworms modify soil water characteristics in different ways. The anecic L. terrestris and the endogeic A. caliginosa showed the tendency to enhance the drying of the topsoil and subsoil. Their intensive and deep burrowing activity seemed to enhance the exchange of water vapor due to a better aeration in the soil. In contrast, the epigeic L. rubellus tended to enhance the storage of soil moisture in the topsoil, which might be linked to lower rates of litter loss from soil surface and thus a thicker litter layer remaining. A. caliginosa led to considerable higher water infiltration rates and faster water discharges in the subsoil, relative to the other species, probably due to a high soil dwelling activity.

Vermiculture

The term "vermiculture" refers to the cultivation of epigeic earthworms grown in an organic matter substrate with no soil. Rearing soil dwelling earthworms undercontrolled conditions requires an understanding of their needs. Many earthworm species can exhibit a degree of plasticity in behavior, so general maintenance does not necessarily require extremely large containers. L. terrestris for example does not need access to a vertical borrow and can be bred in pots which may be only a few cm in depth (Butt, 2009).

References

Butt, KR. 2009. Collection and rearing of earthworms. Workshop Kommission III der DBG, 20-21.03.2009, Trier, Germany

Emmerling, C, M Schlotter, A. Hartmann, and E. Kandeler. 2002. Functional diversity of soil organisms- a review of recent research activities in Germany. JPNSS 165:
408-420.

Ernst G, D Felten, M Vohland, and C Emmerling. 2009. European Journal of Soil Biology 45: 207-213.

Lavelle, P. and A.V. Spain. 2001. Soil Ecology. Kluwer Academic Publishers. Dordrecht, 654p
Photo source:

L. FitzPatrick at http://blog.southtownstar.com/

The role of mycorrhiza in the mineral nutrition of plants

2010-08-29T06:40:00.005+08:00

Mycorrhiza is the association between fungi and the roots of higher plants. The term was introduced by the German scientist A.B. Frank in 1885 (Mengel and Kirkby, 2001). Mycorrhiza is considered as the most widespread association between microorganisms and higher plants. On a global scale, between 86% and 94% of plants are mycorrhizal (Brundrett 2009). All Gymnosperms as well as 83% and 79% of dicotyledonous and monocotyledonous plants, respectively, are mychorrhizal (Marschner 1995). Nonmycorrhizal plants can be found in stressed soil environments (very dry or saline, waterlogged, severely disturbed as in mining areas, infertile) or even in very fertile soils. Mycorrhizas (or mycorrhizae) are absent under all environmental conditions in the Cruciferae and Chenopodiaceae (Marschner, 1995). Generally, in root-fungus association the fungus is strongly or wholly dependent on the higher plant, whereas the plant may or may not benefit from the association. It is not also essential for plant survival except in some plants like orchids. Mycorrhizal associations are therefore either mutualistic, neutral, or parasitic depending on the circumstances although mutualism is the dominant type.

Groups of mycorrhizas

Two mycorrhizal groups according to how the fungal mycelium relates to the root structure:
a) Endomycorrhizas. The fungi live inside the cortical cells of the roots and also grow intercellularly. The best known type is the vesicular-arbuscular mycorrhiza (VAM). This is widespread in cultivated soils.
b) Ectomycorrhizas. This group of mycorrhiza occurs mainly on roots of woody plants and only occasionally on herbaceous and graminaceous perennial plants. Some temperate tree species like beech, oak, spruce and pine cannot survive without ectomycorrhiza (Schachtschabel et al., 1998). They form a sheath or mantle of fungal mycelium over the surface of fine roots. The hyphae penetrate into the intercellular spaces of the root cortex and it extends outward into the soil.

Role of mycorrhizas in the mineral nutrition of host plants

Mycorrhizas are very important in the uptake of nutrients such as P, N, K, Cu, Zn and Ca by plants especially in soils low in these nutrients. Since P is the most limiting nutrient in tropical soils, mycorrhizas are vital for improving P nutrition particularly for cultivated plants. External hyphae can absorb and translocate P to the host from soil outside the root depletion zone. The thin mycorrhizal hyphae (2-4 μm in diameter) are able to penetrate soil pores not accessible to the root hairs which are about five times larger than the hyphae (Kirkby and Mengel, 2001). For example, studies have shown that the heavily mycorrhizal root of cassava enables it to grow well in phosphate-deficient soils where other crops fail (Wild, 1993). Also, a long-term study at the National Abaca Research Center at VSU (Armecin and Geneston-Asio, 2004) has provided the first clear evidence that abaca plant (Musa textilis) is mycorrhizal although colonization was relatively low (18-22%). In alkaline soils, mycorrhiza can prevent iron and manganese deficiencies. Mycorrhizas are also known to protect the plant from soil borne pathogens.

Recently, Lambers et al. (2010) reported that terrestrial plants (except epiphytes, parasites and carnivorous species) acquire most mineral nutrients from the soil primarily via two pathways: 1) direct absorption through the roots, and 2) indirect absorption through symbiotic mycorrhizal fungi. The majority of plants can take up phosphorus via both pathways but depend primarily on mycorrhizal fungi to acquire phosphorus.

References

Armecin RB and LG Asio. 2004. Effects of vesicular-arbuscular mycorrhizal fungi inoculation on Abaca (Musa textilis). Unpublished research report. NARC, VSU, Baybay, Leyte.
Brundrett, M. 2009. Plant and Soil 320: 37-77.
Lambers H, MC Brundrett MC, JA Raven and SD Hopper. 2010. Plant and Soil 334:11-31.
Marschner, H. 1995. Mineral Nutrition of Higher Plants. 2nd ed., Academic Press, London.
Mengel, K. and E.A. Kirkby. 2001. Principles of Plant Nutrition (5thed.). Kluwer Academic Publishers, Dordrecht, 849pp.
Schactschabel P., H.P. Blume, G. Brümmer, K.H. Hartge and U. Schwertmann. 1998. Lehrbuch der Bodenkunde (14th ed.). Ferdinand Enke Verlag, Stuttgart, 494pp.
Wild, A 1993. Soils and the Environment. Cambridge University Press, Cambridge, 287pp.

Photo Sources:
1. G. Quinn at http://www.finegardening.com/
2. Nathan Brandt, Iowa State University Extension News at http://www.extension.iostate.edu/

Relation between properties and age of soils in the Amazon forest

2010-06-06T11:20:00.010+08:00

The Amazon Basin is that part of South America drained by the Amazon River and its tributaries. It has a tropical climate with an annual rainfall of 1500-2500mm, and a day temperature of 30-35 degrees Celsius (Wikipedia).

Much of what we now know about tropical soils was derived from many years of research in the Amazon rainforest. It is now widely known that this very important rainforest is growing on largely infertile and highly wethered soils called Ferralsols in the IUSS World Reference Base classification or Oxisols in the USDA Soil Taxonomy (see photo of typical soil profile).

It has been suggested by some ecologists that the efficient nutrient cycling and the periodic dust deposition from Africa explain why the infertile soils are able to support the lush rainforest vegetation.

In the recent issue of the international journal Biogeosciences Discussions, Quesada and colleagues reported the results of their interesting study on the soils in the Amazon Basin. Highlights of their findings are as follows:

1. There were large variations of soil chemical and physical properties across the Amazon Basin. The properties varied, as predicted, along a gradient of pedogenic development or in other words with soil development. Contrary to the popular notion especially among ecologists and foresters, the study showed that the Amazon soils varied from young to old soils (e.g. Gleysols and Cambisols to Alisols, Acrisols and Ferralsols).

2. Nutrient pools increased slightly in concentration from the youngest to the intermediate aged soils after which it declined gradually in the older soils. The lowest values of nutrients were found in the most weathered (or oldest) soils.

3. Soil physical properties were strongly correlated with soil fertility, with favorable physical properties occurring in highly weathered and nutrient depleted soils. The least weathered and more fertile soils had higher incidence of limiting physical properties.

4. Soil phosphorus concentrations varied with the degree of weathering. Higher P concentrations were observed in younger than in older soils which agreed with results of earlier chronosequence studies like that of Walker and Syers (1976).

5. Phosphorus availability in the younger soils was governed by the weathering of the primary and secondary minerals (particularly apatite) which in turn was controlled by soil pH.

Reference

Quesada CA, Lloyd J, Schwarz M and co-workers. 2009. Chemical and physical properties of Amazon forest soil in relation to their genesis. Biogeosciences Discussions 6: 3923-3992.

Soil excursion to Southern Leyte, Philippines with Prof. R Jahn

2010-05-13T21:36:00.013+08:00

On 09 April 2010, we organized a soil excursion to Southern Leyte for selected graduate students pursuing MSc degree in Soil Science at the Department of Agronomy and Soil Science of Visayas State University in Baybay, Leyte. The main objective of the activity was to observe the important soils of the province.

Prof. Dr. Reinhold Jahn of Martin Luther University (Germany), former Chairman of the Soil Geography Commission of the International Union of Soil Sciences (IUSS), served as the resource person. The participants included Grace Enojada, Marilou Sarong, Katrina Piamonte, Deejay Maranguit, Glenn Largo, and Raffy Rodrigo.

The group first focused on the young soils in the alluvial plains which are generally used for lowland rice production. Prof. Jahn discussed the important features of paddy (rice) soils particularly gleying, mottling, and the occurrence of plow pan.

During his recent field work in the Banaue rice terraces in northern Luzon, Prof. Jahn noted that plow pan is generally absent in the rice terraces since puddling is not part of the normal cultural managment practices there. Puddling is the process of destroying the structure of rice soil by cultivating it when it is wet inorder to homogenize the soil and to produce a watertight soil paste to hold water on the soil surface.

In the mountainous portion of Southern Leyte, highly weathered soils (Ultisols) that developed from basalt and other igneous rocks are widepsread. The group examined an Ultisol soil profile that was very deep and heavy clay, and which showed the occurrence of mottles and exfoliation weathering of rock in the lower portion of the profile. Ultisols are acidic, clayey, and have generally low nutrient status. They are the most widespread soils in the Philippines.

The group also found a very beautiful soil profile of an Ultisol near the town of Silago. It formed from two parent materials (bisequm) and clearly showed lithologic discontinuity (i.e. the heterogeneity of the parent rock material).

Hydrogen peroxide is not a good reagent for the removal of soil organic matter

2010-04-24T17:09:00.008+08:00

Organic matter (OM) is the most important cementing agent of soil particles. Soils containing high amount of OM (like the dark Leyte soil shown below) generally have good aggregation (i.e. the sand, silt and clay particles are glued together by the OM). Removal of OM using chemical reagents is thus an important pretreatment in textural or particle size analysis as well as in the evaluation of soil mineralogy, cation exchange capacity, and surface area.

Hydrogen peroxide (H2O2) which was first used in 1923 by G.W. Robinson to destroy soil organic matter, is the most widely used chemical reagent for removing OM in soil laboratories worldwide. However, there have been some scientific reports indicating that it may not be a good reagent for that purpose due to some unwanted effects on the mineral soil particles. In the Philippines, it is not also easy to procure large volumes of hydrogen peroxide since it requires clearance from the Philippine National Police.

Robert Mikutta and colleagues from the Institute of Soil Science and Plant Nutrition of the University of Halle-Wittenberg, Germany (see photo below of the soil mineralogy laboratory), in a study published in the Soil Science Society of American Journal, Vol. 69 (2005), compared the performance of the three most accepted reagents for OM removal: hydrogen peroxide, sodium hypochlorite (NaOCl), and disodium peroxodisulfate (Na2S2O8).

They found that: 1) removal of OM from soil is mostly incomplete with efficieny of removal varying with reaction conditions and sample properties; 2) sodium hypochlorite and disodium peroxodisulfate are generally more effective in removing OM compared with hydrogen peroxide; 3) alkaline conditions and additives favoring dispersion and/or decomposition of OM such as sodium pyrophosphate, are crucial for OM removal; and 4)OM removal can be little in soils containing high amounts of clay-sized minerals like Fe oxides, poorly crystalline Fe and Al phases, and expanding clay types.

The authors also found that the use of hydrogen peroxide to remove OM should be avoided for the determination of mineral particle properties since the treatment may promote organic-assisted dissolution of poorly crystalline minerals at low pH, disintegration of expandable clay minerals, and transformation of vermiculite into mica-like
products due to ammonium (NH4) fixation. (Photo below shows clay collection for mineralogical analysis after OM removal by chemical reagent and physical dispersion).

They concluded that sodium hypochlorite and disodium peroxodisulfate are less harmful for soil minerals than hydrogen peroxide; prolonged heating to >40 degrees C during any pretreatment may transform poorly crystalline minerals into more crystalline ones; and sodium hypochlorite can be used at 25 degrees C and can thus prevent heat-induced soil mineral changes.

Simply put: sodium hypochlorite is better than hydrogen peroxide in removing OM from soil samples.

Reference

Mikutta R, Kleber M, Kaiser K and Jahn R. 2005. Organic matter removal from soil using hydrogen peroxide, sodium hypochlorite, and disodium peroxodisulfate. Soil Science Society of America Journal 69: 120-135.

Soil degradation in the Philippines

2010-03-14T10:57:00.009+08:00

Soil degradation is a severe global problem of modern times. About 6 million hectares of agricultural land worldwide become unproductive every year due to the various soil degradation processes. The problem is much more serious in tropical than in temperate areas since tropical soils are more prone to degradation because of the nature of their properties and the prevalent climatic conditions. Countries in Asia and Africa that depend upon agriculture as the engine of economic growth are believed to suffer the greatest impact of soil degradation. In the Philippines, soil degradation is one of the most serious ecological problems today. Also, the National Action Plan (NAP) for 2004 to 2010 identified soil degradation as a major threat to food security in the country. NAP reported that about 5.2 million hectares are seriously degraded resulting to 30 to 50% reduction in soil productivity.
Soil degradation is defined as the process which lowers the current or future capacity of the soil to produce goods or services. It implies long-term decline in soil productivity and its environment-moderating capacity. The concept of soil degradation was first used by Kostychiev and Korchinski in 1888 to describe a natural soil change. Since natural degradation is slow, the present concept of soil degradation according to the Global Assessment of Soil Degradation (GLASOD) focuses on a human-induced process. Soil degradation occurs because of drastic changes or disruption in the normal processes of soil formation due to human activities.

In a review paper on the problem of soil degradation in the Philippines published in the Annals of Tropical Research vol. 31, we (Asio et al) revealed that soil erosion is the most widespread process of soil degradation and is also the most studied in the country. Other important but less studied soil degradation processes include loss of nutrients and organic matter, salinization, acidification, pollution, compaction, and subsidence. Studies reviewed have shown that the widespread degraded upland soils possess chemical and physical constraints for crop growth like acidic or calcareous pH, low organic matter and nutrient contents, shallow solum, presence of toxic substances and compaction.

There is a need for more data on the physical and socio-economic characteristics of degraded lands to aid in the formulation of appropriate soil management strategies to support biodiesel production in these unproductive lands which is now being promoted by the Philippine government. Also, there is the danger that the use of the degraded lands for intensive and long-term biodiesel production without the appropriate soil management would cause further soil deterioration and thus aggravate the ecological problems that are now occurring.

Reference
Asio VB, Jahn R, Perez FO, Navarrete IA, and Abit SM Jr. 2009. A review of soil degradation in the Philippines. Annals of Tropical Research 31: 69-94

The Physical Environment of Mt. Pangasugan, Leyte, Philippines

2010-03-14T10:25:00.011+08:00

Geology

Mt. Pangasugan is generally built up by andesitic and basaltic pyroclastic rocks (referred to as Pangasugan formation) which are mostly of Quaternary and Tertiary origin. This rock formation is characterized by weak consolidation, lithologic discontinuities, abundance of rock outcrops, and shearing due to the occurrence of the Philippine fault line approximately at the center of the mountain range. Minor earthquakes are relatively frequent in the area. All these geological characteristics indicate that the area is unstable.

Geomorphology

The morphology of Mt. Pangasugan is largely the result of the combined effects of volcanism, erosion, faulting and tectonic uplift. Mt. Pangasuagn rises abruptly from the narrow alluvial coastal plain along the Camotes Sea into a vertical wall-like rock mass with a maximum height of about 1100 m above sea level (asl). The air distance between the sea level and the peak of the mountain is less than 3 km. This short distance suggests extremely high erosion energy potential which is visible in the form of waterfalls particularly during periods of high rainfall. The west-facing slope of the mountain is deeply dissected by several short parallel streams that empty into the Camotes Sea. The V-shaped valleys, which indicate youthful stage, coupled by the unconsolidated nature of the rock material, cause widespread landslides during typhoon periods.

Climate

The climate of the area is a humid tropical monsoon climate with no pronounced maximum rain period and no dry season (Type 4 of the Coronas climatic classification). It has an average annual rainfall ranging from 2600 mm in the coastal lowland, to more than 3000 mm at higher elevations. Average temperature in the plain is 27 degrees Celsius which decreases by an average of 0.6 degree Celsius per 100 m rise in elevation (i.e. at 500 m elevation, the average temperature is 24 degrees Celsius). Two types of monsoon winds tremendously influence the over-all climate of the area. From June to October, a southwest monsoon (Habagat) occurs which enhances rainfall in the area (western side of mountain). From November to February, the northeast monsoon (Amihan) follows which generally coincides with cyclonic disturbances thereby bringing plenty of rain particularly to the eastern side of the mountain range.

Pedology

The soils of the mountain can be grouped into four: the old soils in the mountain footslopes (approximately below 200m asl), the mature soils in the mountain midslopes (approximately between 200 and 400m asl), the young soils in the upper slopes (approximately above 400m asl) and the undeveloped soils in very steep slopes.The old soils (Ultisols) are deep, clayey, acidic and infertile. They are relatively stable although landslides may occur. The mature soils (Alfisols) are generally fertile and productive. The young soils in the upper slopes (Andisols) result from the fast weathering of andesitic rocks. They have excellent physical condition but are acidic and generally low in phosphorus. Because of their weak profile development and amorphous clay mineralogy, these soils are unstable and prone to landslides and erosion. The undeveloped soils on steep slopes (Inceptisols and Entisols) have low productivity due to their shallow profile, abundance of rock fragments and steep slopes. They are also prone to erosion.

References

Asio V.B.1996. Characteristics, weathering, formation and degradation of soils from volcanic rocks in Leyte, Philippines. Hohenheimer Bodenkundliche Hefte 33, Stuttgart, Germany, 290pp.

Quimio, J.M., V.B. Asio, J.M. Alkuino, B.B. Dargantes and P.S. Muga. 1997. Initial Environmental Examination of the Leyte-Mindanao Interconnection Project. NPC, Quezon City, 151pp.

Biological nitrogen fixation in corn

2010-03-08T23:52:00.004+08:00

Corn (Zea mays L.) can establish rhizospheric or endophytic associations with various nitrogen-fixing bacteria (diazotrophs) such as Azospirillum, Klebsiella, Pantoea, Herbaspirillum, Bacillus, Rhizobium etli and Burkholderia. Most of these diazotrophs can grow in the intercellular tissue of plants without causing any disease.

Biological nitrogen fixation (BNF) is the biological process by which nitrogen (N2) in the atmosphere is converted to ammonia by an enzyme called nitrogenase. The screening of plant genotypes for their enhanced ability to acquire nitrogen by BNF can reduce the use of expensive nitrogen fertilizers in several important crops like sugarcane, rice, wheat and corn. It can greatly benefit particularly the poor farmers of developing countries.

In a recent study aimed to quantify the symbiotic biological nitrogen fixing activity of a range of commercial corn cultivars, Montanez et al. (2009) demonstrated that corn cultivars obtain significant nitrogen from BNF, the level of which varied with corn cultivar and nitrogen fertilization level. The study showed that some cultivars were more sensitive than others to nitrogen application and that 15N isotope dilution method is a useful tool to screen and select corn cultivars with any potential BNF.

Reference

Montanez A, Abreu C, Gill PR, Hardarson G, and Sicardi M. 2009. Biological nitrogen fixation in maize (Zea mays L.) by 15N isotope dilution and identification of associated culturable diazotrophs. Biology and Fertility of Soils 45: 253-263

Invitation to the 13th Scientific Conference of PSSST on 27-28 May 2010

2010-02-24T05:04:00.008+08:00

The Philippine Society of Soil Science and Technology (PSSST) will hold the 13th Annual Meeting and Scientific Conference in Puerto Princesa City, Palawan, on 27-28 May 2010. Following is the formal announcement by the PSSST President Constancia G. Mangao.

PHILIPPINE SOCIETY OF SOIL SCIENCE AND TECHNOLOGY, INC. c/o BUREAU OF SOILS AND WATER MANAGEMENT
Elliptical Road corner Visayas Avenue, Diliman

February 16, 2010

Dear Fellow PSSST Members:

The Philippine Society of Soil Science and Technology, Inc. (PSSST), a duly recognized non-stock, non-profit professional society registered with the Securities and Exchange Commission, will hold its 13th Annual Meeting and Scientific Conference on May 27-28, 2010. This will be an important gathering of the members of the Society and interested professionals to share the latest developments and findings in soil science and technology.

In line with the conference’s theme, Soil and Water Management Approaches for Climate Change Mitigation and Adaptation, Puerto Princesa City, Palawan was chosen as the venue. Puerto Princesa City is a first class city with breath-taking sights, pristine sand beaches, lush rainforests, water falls, and beautiful islands with spectacular limestone karst landscape in its underground river, a significant habitat for biodiversity conservation. The city instituted environmental protection measures against the spoilers of nature.

We believe that you are an important partner to deal with in promoting soil technologies in the country. In this regard, we are inviting you to attend and actively participate in this annual meeting and scientific conference. The registration fee is six thousand six hundred fifty pesos (Php 6,650.00) which is inclusive of food and accommodation, attendance to scientific sessions, and symposium kits. Transportation and post conference tour are excluded in the registration fee.

Attached is the final announcement for your reference. For further details, please contact Dr. Virginia M. Padilla (vmpadilla02@yahoo.com/0919-66-8609) or Dr. Constancio A. Asis, Jr. (asis_tony@yahoo.com /09077441188).

Thank you very much. Very truly yours,

CONSTANCIA G. MANGAO
President

Response of corn to chicken dung and rice hull ash application and mycorrhizal fungi inoculation

2010-01-23T19:08:00.006+08:00

By Luz Geneston-Asio, Central Analytical Services Lab, VSU, Baybay, Leyte

The use of locally available and cheap organic fertilizers like chicken dung and rice hull ash which have the ability to increase crop yield and at the same time improve soil quality is becoming popular among farmers in many places in the Philippines. In addition, considering that the world demand for corn as food and feed is projected to greatly increase in the coming decades, there is a need to explore the use of such materials for corn production.

We evaluated the growth and yield responses of corn to chicken dung and rice hull ash application a well as to mycorrhizal fungi inoculation. The experiment was laid out in a split-plot in Randomized Complete Block Design consisting of three replications. Vesicular-arbuscular mycorrhizal (VAM) inoculation served as the main plot while application of fertilizer was designated as the subplot. The fertilizer treatments included the following: To-control, T1-inorganic fertilizer (60-60-60 kg/ha N, P205, K20), T2-chicken dung alone (60 kg/ha N), T3-chicken dung (as in T2) + 30 kg/ha rice hull ash. The experimental area had an alluvial clay loam soil with pH of 5.8 and moderate fertility status.

Results showed that VAM inoculation significantly increased the total N but not the total P, K, and Ca contents of the tissue of corn plant. However, VAM inoculation did not significantly affect the grain yield and the agronomic characteristics of corn. In contrast, fertilization using inorganic fertilizer, chicken dung or chicken dung plus rice hull ash enhanced the early tasseling and silking but not emergence and maturity of corn. The application of fertilizers significantly increased plant height as well as the fresh stover yield compared to the control plants.

The inorganic fertilizer, chicken dung, and chicken dung plus rice hull ash significantly increased the number of ears per plant, ear length, number of grains per ear, weight of 1000 seeds, grain yield and harvest index. The use of chicken dung combined with rice hull ash for corn production is a good substitute for the inorganic fertilizer in increasing corn grain yield. (Above photo shows VAM infection in the root of corn from this study).

Reference

Luz Geneston-Asio and Alfredo B. Escasinas. 2006. Response of corn to chicken dung and rice hull ash application and mycorrhizal fungi inoculation. Annals of Tropical Research 26: 23-36

Effects of Lantana camara on soil properties and neighboring plants

2010-01-23T16:00:00.003+08:00

Lantana camara Linn, locally called Utot-utot, Koronitas or Kantotoy in the Philippines, is a shrub which originated from tropical America. It is considered as one of the worst invasive plant species and is a noxious weed in many parts of the world.

The plant is known to suppress the regeneration of neighboring plants through allelopathic effects (by releasing volatile and non-volatile chemicals from its tissues and residues). The spread of Lantana is aided by the characteristic of its leaves which is somewhat poisonous to animals while its fruit is a delicacy for many birds which distribute the seeds (Wikipedia).

In a recent study published in Geoderma journal, Ling Fan and co-workers evaluated the chemical and microbiological properties of the soil underneath the canopy of Lantana camara as well as the soil away from it. They also investigated the effect of Lantana on the growth of three neighboring plant species (ryegrass, mungbean, and radish).

Results revealed that the soils underneath the canopy of Lantana had higher pH, total N, total P, available N and available P than the soils on the edge of the canopy and 2-5 m away from the Lantana plant. Soil respiration, enzyme activities, and microbial biomass N and P were higher in the soils underneath the canopy of Lantana than that away from it.

The study showed that Lantana camara improved soil fertility, accelerated N and P cycles, utilized carbon substrate more effectively, had higher functional diversity and did not inhibit the growth of the neighboring plant species.

Reference
Ling Fan, Yan Chen, Jian-gang Yuan and Zhong-yi Yang. 2010. The effect of Lantana camara Linn invasion on soil chemical and microbiological properties and plant biomass accumulation in southern China. Geoderma 154: 370-378.

Characteristics and formation of rain forest soils from Quaternary basalt in Leyte, Philippines

2009-10-10T13:45:00.006+08:00

The classical view about soils of tropical rain forest ecosystems is that these soils are old, acidic, and infertile. It is now widely acknowledged that this view which has greatly influenced research and management of the fragile rain forest ecosystem during the last several decades is largely a misconception. Although highly weathered soils (Oxisols or Ferralsols) are the most dominant soils in the humid tropics, tropical soils range from relatively young fertile soils (e.g. Inceptisols) to the highly weathered infertile soils (e..g. Oxisols). The extent of highly weathered soils is less in geologically young areas like in much of SE Asia.

More detailed investigations of rain forest soils are vital for the sustainable management of this threatened ecosystems. These could also lead to a better understanding of the response of rain forests to climate change.

Navarrete et al. (2009) recently conducted a study to evaluate the physical, chemical and mineralogical characterisitics of rain forest soils in Leyte, Philippines. Some of the important findings of that study include:

1) Soils along the catena studied showed minimal variations in their morphological, physical and chemical properties. This has important ecological implications as it tends to not support the idea that high soil spatial variability at short distances in rain forest ecosystems is a major factor for its high biodiversity.

2) The dominant soil-forming processes that produced the soils in the study area are weathering, loss of bases and acidification, desilification, ferrugination, clay formation and translocation, and structure formation. The loss of bases and acidification due to rapid leaching are shown by the low base saturation, very low exchangeable bases, acidic pH, and the low contents of total Ca, Na, Mg, and K. The degree of desilification is almost unifrom in all soils and may have reached 12-19% of that found in the parent material. Ferrugination is shown by the increased loss of bases, halloysitic and kaolinitic mineralogy, high contents of iron oxides and low base saturation. Clay formation and translocation are reflected by the high clay contents particularly in the middle part of the soil profile. Soil structure formation is exhibited by the good soil physical condition.

3) The nature of the basalt parent rock and the climatic condition prevailing in the area as well as its relief appear to be the dominant factors affecting the development of the soils.

Reference

Navarrete IA, K Tsutsuki, VB Asio, R Kondo. 2009. Characteristics and formation of rain forest soils derived from late Quaternary basaltic rocks in Leyte, Philippines. Environmental Geology 58: 1257-1268.

Lead pollution due to vehicular emissions in urban areas in the Philippines

2009-08-19T21:04:00.004+08:00

Lead (Pb) has been known to be toxic since ancient times. It is a widespread contaminant in soils and Pb poisoning is one of the most prevalent public health problems in many parts of the world. It was the first metal to be linked with failures in reproduction. It can cross the placenta easily. It also affects the brain, causing hyperactivity and deficiency in the fine motor functions, thus, it results in damage to the brain. The nervous systems of children are especially sensitive to Pb leading to retardation. Pb is cardiotoxic and contributes to cardiomyopathy (disease of the heart muscle leading to the enlargement of the heart).

Pb is released into the environment from the weathering of Pb-containing rocks, the industry, and the combustion of fossil fuels. Emissions from vehicles are thus a major source of environmental contamination by Pb especially in cities. Ona et al. (2006) conducted a study that looked into Pb pollution in selected urban areas in the Philippines with the following objectives: (1) to determine the levels of Pb in soil from selected urbanized cities in central region of the Philippines; (2) to identify areas with soil Pb concentration values that exceed estimated natural concentrations and allow- able limits; and (3) to determine the possible sources that contribute to elevated soil Pb concentration (if any) in the study area.

The study focused on the determination of Pb levels in soils of selected cities in Luzon, Philippines. The sites included: Site 1 – Tarlac City in Tarlac; Site 2 – Cabanatuan City in Nueva Ecija; Site 3 – Malolos City in Bulacan; Site 4 – San Fernando City in Pampanga; Site 5 – Balanga City in Bataan; and Site 6 – Olongapo City in Zambales. Soil samples were collected from areas along major thoroughfares regularly tra- versed by tricycles, passenger jeepneys, cars, vans, trucks, buses, and other motor vehicles. Soil samples were collected from five sampling sites in each of the study areas. Samples from the selected sampling sites were obtained approximately 2 to 3 meters from the road. Analysis of the soil samples for Pb content was conducted using an atomic absorption spectrophotometer.

Findings revealed Pb levels ranging from 1.5 to 251 mg kg–1 in all the soil samples collected from the 30 sampling sites in the six cities. Elevated soil Pb levels i.e.greater than 25 mg kg–1 Pb) were observed in five out of the six cities sampled. Site 4 showed the highest Pb concentration (73.9 ± 94.4 mg kg–1), followed by Site 6 (56.3 ± 17.1 mg kg–1), Site 3 (52.0 ± 33.1 mg kg–1), Site 5 (39.3 ± 19.0 mg kg–1), and Site 2 (38.4 ± 33.2 mg kg–1). Soil Pb level in Site 1 (16.8 ± 12.2 mg kg–1) was within the estimated natural Pb concentration range of 5 to 25 mg kg–1. The study found that the average soil Pb concentration from the six cities studied were below the maximum tolerable limit according to World Health Organization (WHO) standards. The high Pb concentration in Site 4 was attributed by the authors mainly to vehicular emission.

The researchers concluded that "only one (San Juan in Site 4) of the thirty sampling sites showed a Pb concentration above the WHO permissible limit of 100 mg kg–1. San Juan in Site 4 had a Pb concentration of >250 mg kg–1. On the average, elevated Pb concentration was evident in the soil samples from San Fernando, Olongapo, Malolos, Balanga, and Cabanatuan. The average soil Pb concentrations in these cities exceeded the maximum estimated natural soil Pb concentration of 25 mg kg–1. Average soil Pb concentration in Site 1 (16.8 mg kg–1) was well within the estimated natural concentration range of 5 to 25 mg kg–1. Data gathered from the study areas showed that elevated levels of Pb in soil were due primarily to vehicular emissions and partly to igneous activity."

Reference
Ona LF, Alberto AMP, Prudente JA and Sigua GC. 2006. Levels of lead in urban soils from selected cities in a Central Region of the Philippines. Environ Sci & Pollut Res 13 (3) 177 – 183

The causes of the Guinsaugon landslide

2009-08-12T20:47:00.006+08:00

On 17 February 2006, a catastrophic landslide buried the village of Guinsaugon, the second largest village of St. Bernard town (Southern Leyte, Philippines) killing more than a thousand residents and displacing approximately 19,000 people. The landslide originated on an approximately 800 m high escarpment produced by the Philippine Fault that bisects Leyte and the major islands of the Philippines. In a recent article which synthesized the papers presented during an international conference in Leyte 2008 and published in the international journal Bulletin of Engineering Geology and the Environment, Guthrie and co-workers (2009) arrived at the following conclusions:

"The approximately 15 million m3 landslide was a result of progressive failures and tectonic weakening in a region made especially vulnerable by the inter-reaction of geological/tectonic, climatic and cultural factors. In southern Leyte, geology and tectonics (including historical seismicity, the progressive disintegration of the rock mass, the development of smectite layers and the continuous development and movement of shears within the Philippine Fault Zone) combine in steep rugged terrain to produce a series of massive landslides ([10 million m3) of which the Guinsaugon event is the latest."

"The presence of rice paddies in the valley bottom had a major effect on the mobility of the rock avalanche, which increased the vulnerability of communities established to tend these fields. Having considered the available evidence, it is concluded that the landslide was not triggered by a seismic event that occurred several minutes afterward and that the recorded seismic signature was not a trace of the landslide itself. Rather, it is considered that the earthquake could be a result of tectonic unloading after the landslide occurred, or completely independent of the landslide event."

"The role of climate is, in some respects, similar to that of the seismic event. In terms of the trigger, the storm rainfall that occurred several days prior to the landslide undoubtedly raised pore water pressures in the source rock mass. However, progressive failure relies less and less on pore water pressure as failure becomes imminent. The danger of relying on triggers to ascertain the probability of failure is exemplified by the Guinsaugon event; in the lag time between the end of the period of heavy rainfall and the occurrence of the rockslide-debris avalanche, evacuated residents had returned to their homes. Possible trigger mechanisms can be incidental to the landslide itself; however, the progressive development of a large failure often produces telltale signs that are observable by a community of non-experts."

Our own field investigations have shown two important aspects of the landslide not very well taken up in the report. The first is about the role of the thin layers of mudstone in between thick layers of sandstone/siltstones which could have served as lubricant for the landsliding process. The other is the great possibility that the Guinsaugon village developed on old landslide debris. This was clearly shown by the fact that the lower hills not affected by the recent landslide showed comparable materials as the landslide area. Also, the behaviour of the stream tells us a very important information.

It is very likely that the stream was covered by landslide debris in the past which is the reason why it changed its course and appeared to go around the community. Early settlers may have found the sligthtly elevated part of the area convenient to build their houses since it was elevated (and thus not prone to flooding) but without any idea that it was a landslide debris. The tragic landslide was waiting to happen. It was just a matter of time. Unfortunately, the people were not aware of this.

The role of the paddy fields as claimed by the paper needs more scientific investigation. I am not convinced that it played a major role considering the fact that the debris itself was already saturated with water. The clayey soil material from the hillside probably had more influenced on the movement of the debris than the paddy soil.

Reference

R. H. Guthrie, S. G. Evans, S. G. Catane, M. A. H. Zarco, and R. M. Saturay Jr. 2009. The 17 February 2006 rock slide-debris avalanche at Guinsaugon Philippines: a synthesis. Bulletin of Engineering Geology and the Environment 68:201–213

The problem of high levels of nickel in soils and plants in the ultramafic area in Samar, Philippines

2009-07-24T20:04:00.006+08:00

Contributed by Janice P. Susaya, Sejong University, Seoul, Korea

One of the heavy metals that commonly occur in elevated amounts in natural ecosystems is nickel (Ni). Ni is considered an essential micronutrient for plants, humans, and animals. It can exist in trace amounts in air, food, drinking water, and soils. Although Ni plays an important role in the metabolism of humans and animals, its intake in excesssive amounts or over a prolonged period could pose health ricsks. Studies have shown that children living in polluted areas have hypertrophy of tonsils, enlarged lymphatic nodes, and enlarged livers. There is also evidence that soluble Ni particulate is linked to acute lung injury.

High Ni levels in natural ecosystems commonly come from ultramafic rocks (also called ultrabasic rocks). These are intrusive igneous rocks containing less than 45% silica (SiO2) with high concentrations of Ni, Mg, Fe, Cr, and Co. They are found in many places around the world and are common in many places in the Philippine like in Salcedo in the island of Samar.The watershed has a highly weathered soil (Oxisol) derived from the weathering of ultramafic rock. Previous studies conducted in the watershed revealed excessive levels of Ni, Cu, and Cr in the soil. Many farmers also complain of unexplained health problems which may be related to heavy metal toxicity.

In a study conducted in the Salcedo watershed and recently published in the international scientific journal Environmental Monitoring and Assessment, Susaya and co-workers (Susaya et al., 2009) evaluated the degree of Ni contamination in soils and plants in the watershed. The plants sampled included native species (non-food) such as Phyllanthus amarus, Melastoma affine, and Stachytarpeta jamaicensis as well as cultivated food crops like Calocasia esculenta, Citrullus vulgaris, Artocarpus heterophylla, Moringa oleifera, Psidium guajava, Lycopersicon esculentum, and Solanum melongena.

Results of the study showed that the quantity of total Ni in the soil was significantly high with a mean of 1,409 mg kg-1 while the available Ni was low with a mean of 8.66 mg kg-1. As the levels of total Ni greatly exceeded the maximum allowable concentration for agricultural soils, the site is not suitable for agricultural purposes. Available Ni levels were low due to the tight binding between Ni and the soil components. This explains why all plants investigated did not met the criterion for a Ni hyperaccumulator plant. Comparison of Ni levels between the food plants sampled and its recommended daily intake (RDI) suggests that consumption of a particular food plant grown in the study area is unlikely to pose health problems. However, prolonged consumption of a given food plant with high Ni level or combined consumption of different food plants with high Ni levels can induce accumulation of Ni above the RDI and thus could cause health problems.

Reference

Susaya JP, KH Kim, VB Asio, ZS Chen, and IA Navarrete. 2009. Quantifying nickel in soils and plants in the ultramafic area in Philippines. Environmental Monitoring and Assessment (now available online at http://www.springer.com/environment/environmental+toxicology/journal/10661)

A superheavy new element is named "copernicium"

2009-07-23T15:45:00.006+08:00

Source: Website of GSI Helmholtz Center for Heavy Ion Research, Darmstadt

Element 112 in the periodic table is named in honor of the great astronomer Nicolaus Copernicus (1473-1543). Copernicus discovered that the Earth orbits the Sun ("heliocentric theory"), thus paving the way for our modern view of the world.

The discovering team of scientists at the GSI Helmholtzzentrum für Schwerionenforschung (Center for Heavy Ion Research) in Darmstadt, Germany, led by Professor Sigurd Hofmann (photo) suggested the name „copernicium“ with the element symbol “Cp” for the new element 112. A few weeks ago, the International Union of Pure and Applied Chemistry, IUPAC, officially confirmed the discovery. In around six months, IUPAC will officially endorse the new element's name. This period is set to allow the scientific community to discuss the suggested name "copernicium" before it is finally accepted by IUPAC.

Copernicus was born 1473 in Torun and died 1543 in Frombork, Poland. His discovery that the planets circle the Sun refuted the then accepted belief that the Earth was the center of the universe (or the "geocentric theory"). This finding was pivotal for the discovery of the gravitational force, which is responsible for the motion of the planets. It also led to the conclusion that the stars are incredibly far away and the universe inconceivably large, as the size and position of the stars does not change even though the Earth is moving. Furthermore, the new world view inspired by Copernicus had an impact on the human self-concept in theology and philosophy: humankind could no longer be seen as the center of the world.

With its planets revolving around the Sun on different orbits, the solar system is also a model for other physical systems. The structure of an atom is like a microcosm: its electrons orbit the atomic nucleus like the planets orbit the Sun. Exactly 112 electrons circle the atomic nucleus in an atom of the new element “copernicium”.

Element 112 is the heaviest element in the periodic table, 277 times heavier than hydrogen. It is produced by a nuclear fusion, when bombarding zinc ions onto a lead target. As the element already decays after a split second, its existence can only be proved with the help of extremely fast and sensitive analysis methods. Twenty-one scientists from Germany, Finland, Russia and Slovakia have been involved in the experiments at GSI that led to the discovery of element 112.

Since 1981, GSI accelerator experiments have yielded the discovery of six chemical elements, which carry the atomic numbers 107 to 112. The discovering teams at GSI already named five of them: element 107 is called bohrium, element 108 hassium, element 109 meitnerium, element 110 darmstadtium, and element 111 is named roentgenium.

The goal of the scientific research conducted at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt (founded in 1969) is to understand the structure and behavior of the world that surrounds us. In addition to broadening our understanding of the world, this knowledge also serves as a basis for technological progress in all areas of our lives.

GSI operates a large, in many aspects worldwide unique accelerator facility for heavy-ion beams. Researchers from around the world use the facility for experiments that help point the way to new and fascinating discoveries in basic research. In addition, the scientists use their findings to continually develop new and impressive applications.

The research program at GSI covers a broad range of activities extending from nuclear and atomic physics to plasma and materials research to biophysics and cancer therapy. Probably the best-known results are the discovery of six new chemical elements and the development of a new type of tumor therapy using ion beams.

Heavy metals in the environment and their health effects

2009-07-21T19:49:00.007+08:00

Heavy metals have a density of 6.0 g/cm3 or more (much higher than the average particle density of soils which is 2.65 g/cm3) and occur naturally in rocks but concentrations are frequently elevated as a result of contamination. The most important heavy metals with regard to potential hazards and occurrence in contaminated soils are: arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb) and zinc (Zn).

The sources of heavy metal pollutants are metal mining, metal smelting, metallurgical industries, and other metal-using industries, waste disposal, corrosions of metals in use, agriculture and forestry, forestry, fossil fuel combustion, and sports and leisure activities. Heavy metal contamination affects large areas worldwide. Hot spots of heavy metal pollution are located close to industrial sites, around large cities and in the vicinity of mining and smelting plants. Agriculture in these areas faces major problems due to heavy metal transfer into crops and subsequently into the food chain.

Health effects of selected heavy metals

Arsenic (As). Arsenic is well-known as a poison and a carcinogen. It has an average concentration in the soil of 5 to 6 mg/kg. Its amount in the soil is related to rock type and industrial activity.

Cadmium (Cd). Its toxicity is linked with reproduction problem because it affects sperm and reduces birth weight. It is a potential carcinogen and seems to be a causal factor in cardiovascular diseases and hypertension. Large concentrations of Cd in the soil are associated with parent material (black slates) and most are manmade (burning of fossil fuels, application of fertilizers, sewage sludge, plastic waste).

Chromium (Cr). It is required for carbohydrate and lipid metabolism and the utilization of amino acids. Its biological function is also closely associated with that of insulin and most Cr-stimulated reactions depends on insulin. However, excessive amount can cause toxicity. Toxic levels are common in soils applied with sewage sludge.

Lead (Pb). This has been known to be toxic since the 2nd century BC in Greece. It is a widespread contaminant in soils. Lead poisoning is one of the most prevalent public health problems in many parts of the world. It was the first metal to be linked with failures in reproduction. It can cross the placenta easily. It also affects the brain, causing hyperactivity and deficiency in the fine motor functions, thus, it results in damage to the brain. The nervous systems of children are especially sensitive to Pb leading to retardation. It is also cardiotoxic and contributes to cardiomyopathy (disease of the heart muscle leading to the enlargement of the heart).

Mercury (Hg). This heavy metal is toxic even at low concentrations to a wide range of organisms including humans. The organic form of mercury can be particularly toxic, and the methyl-and ethyl-forms have been the cause of several major epidemics of poisoning in humans resulting from the ingestion of contaminated food, e.g. fish. Two major epidemics in Japan were caused by the release of methyl and other mercury compounds from an industrial site followed by accumulation of the chemicals in edible fish. The poisoning became well-known as Minamata disease.

Nickel (Ni). Nickel occurs in the environment only at very low levels. Humans use nickel for many applications like the use of nickel as an ingredient of steel and other metal products. Foodstuffs have low natural content of nickel but high amounts can occur in food crops growing in polluted soils. Humans may also be exposed to nickel by inhalation, drinking water, smoking, and eating contaminated food. Uptake of high quantities of nickel can cause cancer, respiratory failure, birth defects, allergies, and heart failure (www. Lenntech.com/periodic-chart-elements/Ni-en.htm)

References

Oliver, M.A. 1997. Soil and human health: a review. European Journal of Soil Science 48: 573-592.
Puschenreiter M., O Horak, W. Friesel and W. Hartl. 2005. Low-cost agricultural measures to reduce heavy metal transfer into the food chain- a review. Plant Soil Environ 51: 1-11.
Susaya JP. 2007. MSc thesis. Institute of Tropical Ecology, Visayas State University, Baybay, Leyte, Philippines.

Environmental pollution and the safety of herbal and alternative medicinal products

2009-07-20T20:03:00.005+08:00

There is scientific evidence that many over-the-counter health foods, neutraceuticals, and alternative medicinal products may not be safe. This was revealed in a paper written by Dr. K. Chan of Hongkong Baptist University and published in the international scientific journal Chemosphere.

The paper concluded that “the increase in popularity of such products has brought concerns and fears over the professionalism of practitioners and the quality, efficacy, and safety of their treatment methods and products from herbal and natural sources. These products maybe contaminated with excessive or banned pesticides, microbial contaminants, heavy metals, chemical toxins or adulterated with orthodox drugs."

"The excessive pesticides, microbial contaminants and heavy metals maybe related to the source of these herbal materials if they are grown under contaminated environment or during the collection of these plant materials. Chemical toxins may come from unfavorable or wrong storage conditions or chemical treatment due to storage. The presence of orthodox drugs maybe related to unprofessional practice of manufacturers."

Just a little explanation for the above. Plants growing in polluted soils may absorb the pollutants like heavy metals, pesticides and other harmful substances and store them in their tissues. Studies have shown (e.g. Susaya, 2007) that succulent plant species generally absorb high amounts of heavy metals from the soil. The pesticides may also come from excessive pesticide application to control pests during the production of the herbal plants.

The article is just a reminder to all of us. It may not be true to the products that you are now using. But it may turn out that the fresh herbal plants that we can get from our own backyard maybe safer than the beautifully packed but expensive ones produced somewhere else.

(Photo shows part of the medicinal plant garden of a 12th century castle along Rhein River in Germany.)

Reference

Chan K. 2003. Some aspects of toxic contaminants in herbal medicines. Chemosphere 52: 1361-1371

F.A. Fallou: The Father of Soil Science

2009-07-15T21:53:00.006+08:00

History is one of the most complicated and subjective academic fields since it is greatly influenced by the knowledge, experience, interest, and personal taste of the authors who reconstruct the history of a given event or human endeavour. It also depends on the availability and accuracy of historical records as well as on the degree of detail of the historical account. The renowned historian Norman Davies author of the book "Europe: A History" (Pimlico, London, 1365pp) wrote that "history can be written at any magnification. One can write the history of the universe on a single page, or the life-cycle of a mayfly in forty volumes." Thus, it is not unusual to read many different versions or revisions of the historical account of a past event.

The history of soil science is no exception. Some aspects of it are still controversial such as the one about its founder. Although the Russian geographer Vasilii Vasilevich Dokuchaev (1846-1903) is widely considered as the founder of soil science on the basis of his book “Russian Chernozem” of 1883 which discussed soil formation as a function of the factors climate, parent material, organism, relief and time, a close examination of historical records would reveal that another scientist had made a major contribution two decades before him. He was Friedrich Albert Fallou.

F.A. Fallou (1794-1877) from Zörbig, a small town in Sachsen, Germany is considered by several important authors as the founder of soil science (Blanck, 1949; Joffe, 1949; Strzemski, 1975; Schroeder, 1983; Feger and Makeschin, 2007). In his seminal book Pedologie oder allgemeine und besondere Bodenkunde (Pedology or General and Special Soil Science) of 1862, Fallou justified why soil is a natural body that needs to be studied and argued for the recognition of soil science as an independent natural science. He also introduced the concept of soil profile, discussed the physical and chemical properties of soils and established a soil classification based on parent rock (Asio, 2005).

Contrary to popular notion, it was Fallou in his book of 1862 who first recognized the soil as a natural body and not Dokuchaev who only published his important work two decades later. This was in fact acknowledged by K.D. Glinka (1867-1927) in his lecture during the first international congress of soil science in 1927 although he appeared to downplay Fallou’s contribution and gave the credit to his teacher and countryman Dokuchaev (Glinka, 1927). Dokuchaev’s fame was further enhanced by the fact that Glinka was widely read in North America especially since he was the first president of the International Society of Soil Science. That Dokuchaev who was only about 16 years old and still a young student when Fallou’s influential book of 1862 (Fallou’s sixth book) was published, reinforces the notion that he was influenced by Fallou although according to Johnson et al. (2005) Dokuchaev cited Fallou only once in his important work on chernozem. Whether or not this omission was intentional is unknown. Interestingly, the American landscape pedologist David J. Brown noted that Dokuchaev’s “geologic-geographic investigations” and soil maps were apparently based on the geographic maps (e.g. climate-vegetation maps) of Russia developed by the great natural scientist and founder of geography Alexander von Humboldt (1769-1859) but this was not acknowledged by Dokuchaev in his book (Brown, 2006).

Until now very little is known about Fallou’s book. This can be seen from the fact that most books and papers that discuss soil science history only make brief mention of Fallou’s soil classification which is only part of Fallou’s trailblazing book. The book is divided into two parts. Part I (p. 1–198) is about the general knowledge of soils and Part II (p. 199–487) presents a detailed description of his soil types based on parent rock and is relatively known.

In the preface of Part I, Fallou wrote that "the current books on soil science are just compilation of mixed materials (an aggregate of unorganized materials) from geology, geography, agricultural chemistry and plant physiology." In contrast, he stated that his book "presents for the first time the existing soil knowledge as an interconnected, concise and organized body of knowledge" and thus, as a science. He wrote: "This is the first attempt of this nature; I have blazed a trail that others may follow and improve, it does not matter if it will lead to an entirely new building of knowledge based on other principles and in another style, so that the poor and unrecognized soil science will once and for all be accorded the honor and that it will likewise be recognized as a science."

In the 22-page introduction, Fallou discussed the nature and aims of soil science, justified why soil science should be an independent natural science, and why soil is a natural body that deserves to be studied. In Chapter 1 on Entstehung des Bodens (p. 23–52), Fallou discussed the origin of soils, particularly the role of weathering and related processes like transformation and leaching, although he did not yet use the term leaching.

Chapter 2 on Wesen des Bodens (p. 54–82) is a comprehensive discussion about the nature, origin, and characteristics of the inorganic and organic soil components.

Chapter 3 on Beschaffenheit des Bodens (p. 83–107) is about soil properties such as color, structure, weight, and density, porosity, penetrability, solubility (now erodibility), and moisture content.

Chapter 4 on Räumlichkeit (p. 108–130) is actually about the dimension of the soil body. It focuses on the horizontal dimension in terms of soil distribution in the landscape as well as the vertical dimension in terms of soil depth or thickness. Fallou also discussed the distribution and thickness of the soil in the landscape in relation to elevation and slope and thus, was a recognition of the effect of relief on soil characteristics.

Chapter 5 (p.131–144) is about the inner part of the soil body in terms of the nature of soil layering. Other chapters are about differences between soils (Chapter 6), classification of soils (Chapter 7), and the role of soil in the hydrologic cycle and in plant and animal growth as well as the changes of soil with time (Chapter 8).

In Chapter 8, he wrote that "everything changes itself in form and substance with time... the soil will, like all other things in this world, get not younger but older and in the end will lose its productivity." On his discussion about the chemical processes of soil change with time, Fallou wrote that "weathering in the soil body involves transformation and rearrangement... the most important is the dissolution of the unweathered rock material to release its nutrients for plants use thereby transforming it completely to soil."

Because of the great impacts of their contributions to the development of soil science, Fallou, Dokuchaev, and Liebig are considered by some authors as co-founders of soil science. Some others notably Joffe made a slightly different distinction: Fallou as the father of soil science; Dokuchaev as the founder of modern soil science.

(Note to readers: details of all references can be requested from me)

Selection of plants for phytoremediation of sites contaminated with several metals

2009-06-26T01:34:00.002+08:00

Phytoremediation refers to the use of higher plants to rehabilitate contaminated sites without the need to excavate the contaminant material and dispose of it elsewhere. The use of plants capable of taking up high amounts of metals has been proven effective in the rehabilitation of metal-contaminated soils. Plants are grown for a certain period of time and are then harvested and subjected to composting, compaction, incineration, ashing, pyrolysis, direct disposal or liquid extraction. In principle, the best plants for the purpose are those that can tolerate the polluted soil condition, can absorb high amounts of the contaminants, and have economic value (e.g. flowering plants) so that they can also be a source of income. Thus, selection of the suitable plant species is crucial to the success of any phytoremediation program.

In a recent study by HY Lai of MingDao University and and ZS Chen of National Taiwan University published in the International Journal of Phytoremediation, 33 flowering plant species were tested on a 1.3-ha field in central Taiwan. The site is contaminated with multiple metals (As, Cr, Ni, Cu and Zn) due to the continuous irrigation of wastewater from surrounding chemical plants in the last decade. The study used three models for the selection of suitable species: 1) a relative percentage weighting of the growth condition and the metal accumulation capacity of 80% and 20%, respectively; 2) a relative percentage weighting of the growth condition and the metal accumulation capacity of 50% and 50%, respectively; and 3) a relative percentage weighting of the growth condition and the metal accumulation capacity of 0% and 100%, respectively.

The 33 plants included bougainvillea (Bougainvillea spp.), rainbow pink (Dianthus chinensis), serissa (Serissa japonica), French marigold (Tagetes patula), rose of Sharon (Hibiscus syriacus), water willow (Salix warburgu), Chinese ixora (Ixora chinensis), sunflower (Helianthus annuus), Chinese hibiscus (Hibiscus rosasinensis), gold dewdrop (Duranta repens), kalanchoe (Kalanchoe blossfeldiana), creeping trilobata (Wedelia trilobata), garden canna (Canna generalis), garden verbena (Verbena hybrida), Malabar chestnut (Pachira macrocarpa), purslane (Portulaca oloraua), common lantana (Lantana camara), fancy leaf caladium (Caladium xhortulanun), coleus (Coleus blumei), golden trumpet (Allamanda cathartica), common melastoma (Melastoma candidum), Carland flower (Hedychium coronarium), Manaca raintree (Brunfelsia uniflora), yellow cosmos (Cosmos sulphureus), silver apricot (Ginkgo biloba), temple tree (Plumeria acutifolia), orchid tree (Aglaia odorata), star cluster (Pentas lanceolata), blue daza (Evolvulus nuttallianus), cockscomb (Celosia cristata), scandent scheffera umbrella tree (Schefflera arboricola), Bojers spurge (Euphorbia splendens), and croton (Codialum variegatum).

Some of the highlights of the study: Twelve (12) plants out of the 33 tested were selected based on two key factors: 1) ability to tolerate the toxicity of metals (i.e. good growth of the plant) and 2) ability to accumulate high concentrations of metals in the shoot. Using equal weighting (meaning 50% to 50%) of good growth condition (factor No. 1) and of accumulated metal concentrations (factor No. 2), six (6) woody and six (6) herbaceous plant species showed the best potential for phytoremediation of the contaminated site and thus were selected for further testing. These included the following plant species: purslane, garden canna, Bojers spurge, Chinese ixora, croton, kalanchoe, serissa, garden verbena, rainbow pink, French marigold, scandent scheffera umbrella tree, Chinese hibiscus, and sunflower.

The study also revealed that the herbaceous species accumulated higher concentrations of metals and thus have higher “bioconcentration factor” (ratio of metal concentration in shoots to that of the soils) compared to the woody species. The increase of metal concentrations for the herbaceous species were 9.4-fold for Cu, 5.1-fold for Cr, and 8.9-fold for Zn while for the woody species they were 3.1-fold for Cu, 2.5-fold for Cr, and 4.3-fold for Zn.

Reference

Lai HY and ZS Chen. 2009. In-situ selection of suitable plants for the phytoremediation of multi-metals contaminated sites in central Taiwan. International Journal of Phytoremediation 11: 235-250.

Brief history of soil science in the Philippines

2009-06-19T19:15:00.021+08:00

Soil science in the Philippines owes its early development to the Americans. The first soil survey was conducted by C. W. Dorsey an American soil scientist in 1903. In 1921 a Division of Soil and Fertilizer was created under the Bureau of Science which in 1934 was renamed as Division of Soil Survey. In 1951, the Philippine Congress enacted Republic Act No. 622 organizing the Bureau of Soil Conservation with Dr. M. M. Alicante as its first director (BSWM, 2008). Teaching of soil science to students of agricultural science started as early as the 1920s at the University of the Philippines College of Agriculture (UPCA). R. L. Pendleton an American from California who had a doctorate in soil science was one of the pioneer soil science instructors who taught from 1923 to 1935. Pendleton was also an active researcher as reflected by the about 50 papers he published (Pendleton, 1942; Carter, 1958).

Until about the 1960s, much of the work of soil scientists in the Bureau of Soil Conservation (which became Bureau of Soils in 1957) was on soil survey and mapping of soil series in the entire archipelago as well as in promoting soil conservation practices. Because of the major role that soil science played in the green revolution, Philippine soil science enjoyed rapid development in the 1970s and 1980s ("golden age") primarily due to the massive faculty development at the University of the Philippines at Los Banos (UPLB) wherein young faculty members were sent abroad primarily to the U.S.A. for graduate studies, and to the world class soil research that was at the time brewing at the nearby International Rice Research Institute (IRRI) thanks largely to Nyle C. Brady.

NC Brady of Cornell University who taught at UPCA (now UPLB) as Cornell visiting professor after the war returned to Los Banos in 1973 as the third director general of IRRI and remained there until 1981. During Brady's time (and until now), many leading soil scientists from around the world visited or conducted research at IRRI. Some of the internationally well-known soil scientists who worked at IRRI included P.A. Roger (France), H.U. Neue and H.W. Scharpenseel (Germany), F.N. Ponnamperuma (Sri Lanka), T. Yoshida and I. Watanabe (Japan), N. van Breemen and F. Moormann (Netherlands), D.J. Greenland and G.J.D. Kirk (U.K.), R. Bloom and P.A. Sanchez (USA), and S. Sombatpanit (Thailand). By establishing a world class soil research at IRRI and through his soil science textbook (Nature and Properties of Soils), NC Brady has undoubtedly had the greatest impact on Philippine soil science.

At UPLB, the soil scientists who represented, or were product of, the golden age and who became very influential teachers (most of whom have now retired) include: I.J. Manguiat (soil microbiology); R.B. Badayos (genesis, survey and classification); G.O. San Valentin (soil mineralogy and soil chemistry); A. A. Briones and E.P. Paningbatan (soil physics and soil conservation) ; A.M. Briones, D. Carandang and E.D. Reyes (soil chemistry); B.C. Felizardo, C. P. Mamaril, H.P. Samonte, R. Nartea and W. Cosico (soil fertility); I.T. Corpuz (soil conservation and management); A. Alcantara and N.C. Fernandez (land evaluation and environmental studies); and E. Paterno, R. Aspiras and S.N. Tilo (soil microbiology). It should be mentioned that before the golden age, a few pioneers like N.L. Galvez and J.G. Davide had also important contribution to the development of the soil science curriculum in the Philippines. Two foreigners also spent a few years teaching soil science at UPLB: Dr. S. Srinilta (soil physics) and Dr. U. Jones (soil fertility).

Outside UPLB, examples of soil scientists who also stood out during the 1980s and 1990s are J.B. Dacayo of Central Luzon State University and S.S. Magat of Philippine Coconut Authority for teaching and research, respectively.

At present, there is a new generation of well-trained soil scientists, many of whom have obtained advanced degrees from prestigious universities in Japan, Europe, and North America, who are working at various universities, research centers, government agencies, and private organizations throughout the country. Undergraduate and graduate degree programs in soil science are now offered by several universities throughout the country the most important of which are UPLB, Central Luzon State University, Benguet State University and Don Mariano Marcos State University in Luzon; Visayas State University (formerly called ViSCA and LSU) in central Philippines; and University of Southern Mindanao and Central Mindanao University in the southern part of the country. Survey, mapping, and soil fertility evaluation of soils throughout the country are carried out by the Bureau of Soil and Water Management based in Quezon City.

(Note: The article is based on the available historical materials that I have gathered so far. I will revise it when new information becomes available.)

Heavy metal pollution and nutrient deficiency problems in the abandoned Bagacay mine in Samar island

2009-06-14T01:34:00.012+08:00

The National Policy Agenda on the Revitalization of Mining in the Philippines in 2004 gives top priority to the remediation and rehabilitation of abandoned mining sites all over the country. Consequently, the Department of Environment and Natural Resources (DENR) has identified remediation and rehabilitation of several abandoned mining sites as one of its top priorities (MGB-MESD 2006). Among all abandoned mining sites throughout the country needing urgent rehabilitation, the Bagacay Mine ranks first (MGB-MESD 2006).

Bagacay Mine, located at the border of a nature reserve in the western part of Samar Island, was formerly worked for the recovery of pyrite (FeS2) and copper (Cu) for nearly 50 years until its abandonment in 1992. It exhibits many environmental problems such as heavy metal pollution of soil and water and the formation of Acid Mine Drainage. Recent efforts to rehabilitate the area by re-vegetating it with introduced trees species such as mahogany (Swietenia macrophylla), mangium (Acacia mangium) and ipil-ipil (Leucaena leucocephala) as well as some grass species like tiger grass (Thysanolaena maxima) were a total failure.

An environmental assessment by the Mines and Geosciences Bureau (MGB-MESD, 2006) revealed very high levels of heavy metals in sediments (and soils) collected from various parts of the abandoned mining site. For the upstream sediments (soil and sediments deposited by various tributaries unaffected by mining activities), the levels of heavy metals (in mg/kg) were: Fe (5,900 to 96,000), Cu (9 to 2,216), Zn (<1 to 516) and Pb (22 to 694). The midstream materials which included rock and soil materials from the main pit and waste dumps, silt and sediments in the pit, and tailings from the tailing dams were more polluted and showed the following concentrations (mg/kg): Fe (36,400 to 487,500), Cu (220 to 50,100), Zn (100 to 187,700), Pb (8 to 2,341), As (6 to 5,969) and Hg (1 to 13). For the downstream sediments (from the Taft River), the heavy metals concentrations in mg/kg were: Fe (104,300 to 373,500), Cu (466 to 5,279), Zn (2,314 to 7,138), Pb (44 to 354), As (352 to 693) and Hg (2 to 5).

Some native plant species are starting to grow in clumps even in the most polluted portions of the abandoned site. Edralin (2008) collected soil samples around each clump of the native plants as well as plant tissues for chemical analysis. Findings revealed that the soil in the spots where the plants are starting to grow still have very low fertility status and are extremely acidic aside from containing excessive levels of the heavy metals. The study showed that the native plants that start to grow in the area have low nutrient (N and P) requirement and are able to tolerate the polluted condition either by not absorbing (avoiding) the heavy metals or by absorbing high levels of the metals (the study considered only Cu and Pb). The concentration of Cu in the plants such as Saccharum spontaneum L. and Neonauclea formicaria (Elm.) Merr. was positively correlated with the soil OM content. Two fern species Pityrogramma calomelanos (L.) Link and Lycopodium cernuum L. showed the highest concentrations of Cu in their tissues with values that fall within the toxic range for plants. Also, the highest concentration of Pb was shown by Lycopodium cernuun L. and Dicranopteris linearis (Burm.) Underw. with some of their Pb values also falling within the plant toxicity range.

References

Doyle C, Wicks C, Frank N 2007. Mining in the Philippines Concerns and Conflicts. Fact Finding Mission to the Philippines Report. Society of St. Columban, Widney Manor Rd., Knowle, Solihull B93 9AM, West Midlands, UK

Edralin Don Immanuel A. 2008. Copper, lead, nitrogen and phosphorus levels in soils and plants in the abandoned Bagacay mine in Western Samar. MSc thesis in tropical ecology, Visayas State University, Baybay, Leyte, Philippines.

Kabata-Pendias A 2004. Soil-plant transfers of trace element- an environmental issue.
Geoderma 122: 143-149

Mines and Geosciences Bureau - Mining Environment and Safety Division (MGB-MESD) 2006). Environmental Assessment of Abandoned Bagacay Mine Relative to the Proposed Interim Remediation Measures of the World Bank Supported Project. North Avenue, Diliman, Quezon City.

Is soil science in an upswing?

2009-06-13T00:55:00.004+08:00

In many countries, soil science has been traditionally associated with agriculture because of the major function of soil as a medium for plant growth. So it was no surprise that the decline in funding for agricultural research worldwide in the last two decades had taken its toll on student enrolment in agricultural sciences including soil science. But there are good signs that soil science is now experiencing an upswing particularly because of its strong link to environmental management and global warming (soil is a major source and sink of carbon) and to recent increased focus on agriculture.

In a recent paper published in Geoderma, Dr. Alfred E. Hartemink of ISRIC in Wageningen, Netherlands, and Prof. Alex McBratney (University of Sydney) think that soil science renaissance (from French word meaning "rebirth") is currentyl taking place "where novel approaches to thought are combined with a revival of ideas from the past." They noted that renewed interest in food, feed, and fuel production and the publication of numerous reports have brought soils back onto the global research agenda.

Recent reports by the United Nations and other international organizations have highlighted the need for up-to-date and fine resolution soil information and the revival of soil research. They cited as examples of key issues that have been discussed in recent publications soil erosion, nutrient depletion, and pollution particularly in relation to environmental degradation, climate change, and world food production. They estimated that about 3.2 billion euro is spent yearly on soil research worldwide. They urge the soil science community to benefit from the current upsurge in soil science.

Reference

Hartemink AE and A McBratney. 2008. A soil science renaissance. Geoderma 148: 123-129.

Effects of biosolids application on N mineralization

2009-06-07T21:04:00.003+08:00

Sewage sludge is the solid, semi-solid or liquid residue generated during the treatment of domestic sewage. Biosolids are the treated form of sewage sludge. The use of biosolids as soil amendments is widely seen as a way to reduce the accumulation of wastes and at the same time to enhance soil fertility for crop production. Studies have shown that the use of biosolids as soil amendment is an effective means of recovering plant nutrients and improving the physical and microbiological properties of soils.

However, there are problems associated with the use of biosolids such as heavy metal contamination and nitrate pollution. Biosolids containing excessive levels of heavy metals should not be used as soil amendments. As for nitrate pollution due to excessive mineralization, Hseu and Huang (2005) proposed that this maybe avoided by regulating the annual rate of application of biosolids to soil based on crop N requirement and the anticipated net amount of organic N mineralized in the soil treated with biosolids.

In an interesting study aimed to characterize the influence of the application of biosolids on the soil potential for N mineralization (N0) and also to elucidate the kinetics of N mineralization in tropical soils treated with different biosolids, Hseu and Huang (2005) used anaerobic biosolids and aerobic biosolids obtained from the wastewater treatment plants in Kaohsiung and Taipei, Taiwan. The biosolids were applied at rates of 10, 50 and 100 Mg ha−1 to three tropical soils and incubated for 48 weeks.

Findings of the study revealed that addition of both kinds of biosolids to the soil increased N mineralization potential to an extent related directly to the application rate and the N content of the biosolids. However, the cumulative amounts of N mineralized for soil treated with aerobic biosolids greatly exceeded those for the soil treated with anaerobic biosolids. Sandy soil treated with biosolids exhibited a relatively low potential for mineralizing N.

The contamination of the biosolids with relatively high levels of heavy metals such as Cu and Zn did not prevent an increase in N mineralization resulting from the application of biosolids to the soils. Approximately 3–34% of the total N content in the biosolids-treated soils was mineralized for 48-week incubation. Based on a demand of 150 kg N ha−1 for vegetable production in Taiwanese soils, the rate of biosolids application in the three soils are safe and will not cause nitrate accumulation.

Reference

Hseu ZY and CC Huang. 2005. Nitrogen mineralization potentials in three tropical soils treated with biosolids. Chemosphere 59: 447-454.

Could the alkaline soils of the world be the missing carbon sink?

2009-06-03T23:40:00.009+08:00

The missing carbon sink is the large amount of unidentified carbon sink in the global carbon budget. According to the Woods Hole Research Center (2007) the average annual carbon emissions amount to 8.5 Pg (1 Pg or petagram is equal to 1 billion metric tonnes) comprising of 6.3 Pg from combustion of fossil fuels and 2.2 Pg from changes in land use. This is greater than the sum of the annual accumulation of carbon in the atmosphere (3.2 Pg) plus the annual uptake by the oceans (2.4 Pg) which is only 5.6 Pg. The difference of 2.9 Pg (i.e. 8.5-5.6=2.9) is unknown carbon sink required to balance the carbon budget.

Scientists have been searching for this big amount of unknown carbon sink during the last two decades. It was first thought to be located in the ocean considering that it occupies 70% of the earth’s surface. However, most scientists consider that the ocean sink is not big enough to account for the missing carbon (Xie et al., 2009). The next possible location is the world’s forest. In fact, many scientists believe that this large amount of missing carbon is absorbed by land-based carbon sinks particularly forests but estimates indicate that terrestrial ecosystems are a net sink of only 0.7 billion (Woods Hole Research Center, 2007). Some studies have revealed that carbon accumulation is largely counterbalanced by carbon loss from deforestation.

In a study published in Science, an international team of scientists led by Stephens (Stephens et al., 2007) revealed that the missing link may indeed be located in tropical ecosystems. They reported that northern terrestrial uptake of industrial carbon dioxide emissions is smaller than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for carbon dioxide. But whether or not this is enough to account for the missing carbon is not yet clear.

The third possible location of the missing carbon sink is the soil which is one of the largest dynamic carbon pools on earth. In a recent paper published in the journal Environmental Geology, researchers from China revealed a carbon sink which has been largely overlooked in the past. Xie et al. (2009) reported that alkaline soils (i.e. soils with pH > 7.0) on land are absorbing CO2 at a rate of 0.3-3.0 μmol m-2 s-1 with an inorganic, non-biological process. The intensity of this CO2 absorption is determined by the salinity, alkalinity, temperature and water content of the saline/alkaline soils. They estimated the range at 62-622 g C m-2 year-1. Considering that there are about 700 million hectares of alkaline soils around the world, the amount of CO2 absorption could be very significant on a global scale and could be a major part of the missing carbon sink.

References

Woods Hole Research Center. 2007. The missing carbon sink. http://www.whrc(carbon/missingc.htm

Stephens B.B. et al. 2007. Weak northern and strong tropical land carbon uptake from vertical profile of atmospheric CO2. Science 316: 1732-1735.

Xie J, Y Li, C Zhai, C Li and Z Lan. 2009. CO2 absorption by alkaline soils and its implication to the global carbon cycle. Environmental Geology 56: 953-961.

Native tree species affect changes in chemical properties of a highly weathered soil

2009-06-01T16:26:00.003+08:00

Contributed by Juvia P. Sueta, University of Göttingen, Germany

There is growing interest in the use of indigenous tree species in reforestation programs at present. Thought to be well adapted to their native areas, indigenous tree species are able to survive well and strongly influence the soil. However, the lack of published data on their performance often limits their full use and casts uncertainties on whether they have beneficial or negative impacts on the soil. To better understand the role of trees in improving soil quality, an understanding of how nutrient availability changes with time is important (Kelly and Mays, 1999).

In this study which we conducted at the VSU-GTZ reforestation project site (see photo) in Mt. Pangasugan, Leyte, Philippines, we looked at the influence of two native tree species- Parashorea plicata and Dipterocarpus warburgii- on the nature and rate of changes on the chemical properties of a highly weathered soil following a change in land use from Imperata grassland to plantation of indigenous tree species. Monthly sampling of carefully selected plots in two sites (dominated by native or indigenous species) was carried out to evaluate temporal as well as spatial variations in important soil chemical properties. In addition, rates of litter decomposition of the two species were also investigated on the sites.

We found significant monthly variations of soil pH, organic matter content, total N and available P. Significant differences between sites were also observed for organic matter, total N as well as Ca and Mg contents suggesting individual tree species effects. For most of the soil properties evaluated, irregular fluctuations at certain times of the year characterized by periods of high and low availability. This suggests a highly dynamic nutrient cycling within the system.

The influence of these native tree species could be attributed to its litter contribution to the soil. In both sites, some centimeters thick of organic layer could be observed on the soil surface throughout the year. An evaluation of decomposition revealed high rates for both species. This result suggests that aside from being dynamic, the cycling of nutrients also tends to be efficient. This efficient cycling of nutrient may also help explain why these native tree species appeared to grow well despite the inherently low levels of nutrients in this old, highly weathered soil.

References

Kelly JM and PA Mays. 1999. Nutrient supply changes within a growing season in two deciduous forest soils. Soil Sci Soc Am J 63: 226-232.

Sueta JP, VB Asio and AB Tulin. 2007. Chemical dynamics of a highly weathered soil under indigenous tree species in Mt. Pangasugan. Annals of Tropical Research 29: 73-89.

Does Sago palm respond to nitrogen application?

2009-05-29T22:46:00.002+08:00

Sago palm (Metroxylon sagu Rottb.) is widely found in the tropical lowland forest and freshwater swamps across Southeast Asia and New Guinea. Sago, the starch extracted from the pith of sago palm stems, is a staple food for the lowland peoples of Papua New Guinea and the Moluccas (http://en.wikipedia.org/wiki/Sago).

In recent years, the plant has received increased scientific interest as new uses for sago starch like in the manufacture of alcohol, citric acid, bio-ethanol and biodegradable plastics are being explored. One important research issue is on how to increase sago production since, like most wild plants, the mineral nutrition of sago palm is still poorly understood. Little scientific information is also available about its response to fertilizer application.

In a new study published in the international journal Soil Science and Plant Nutrition, Lina and co-workers (Lina et al. 2009) found that N uptake of sago palm increased significantly but inconsistently with increasing N application. The few significant increases in N uptake that were observed did not translate into significant improvements in the growth parameters of sago plant, except for the number of leaflets in the pot experiment. No significant difference was likewise observed between the fertilizer use efficiency at the two fertilization rates (50 and 100 N kg ha-1) for either sago seedling or 2-year-old sago plants.

The study demonstrated that sago palm did take up N from the added fertilizer at low rates. Moreover, it showed that the growth parameters of sago plant are not sensitive to N application suggesting that the form of N and the timing of N fertilization are important factors for sago production.

Reference
Lina Suzette B., Okazaki M, Kimura DS, Yonebayachi K, Igura M, Quevedo MA, and Loreto AB. 2009. Nitrogen uptake by sago palm (Metroxylon sagu Rottb.) in the early growth stages. Soil Science and Plant Nutrition 55: 114-123.

Sofja Kovalevskaja Award for Top Level Junior Scientists and Scholars

2009-05-27T23:50:00.001+08:00

The Alexander von Humboldt Foundation based in Bonn, Germany, announces that it now accepts application for the prestigious Sofja Kovalevskaja Award for Top Level Junior Scientists and Scholars. Below is the official announcement from Dr. Georg Schütte, Secretary General of the Foundation:

Dear Sir or Madam,

Political debate on higher education is currently focused on enhancing the internationalisation of Germany as a research location. Endeavours are underway to improve the showcasing of German research and to create offers designed to promote collaboration between German and foreign researchers. The Alexander von Humboldt Foundation is delighted to be able to contribute to this by announcing once again the Sofja Kovalevskaja Award for Top Level Junior Scientists and Scholars. This attractively endowed research award is an outstanding career opportunity for junior research talents of all disciplines from abroad to establish their own junior research groups at German research institutions.

The award recognises outstanding talent, above average initiative and a creative approach to research and grants exceptional research conditions: The award amount totalling up to 1.65 million EUR provides award winners with valuable risk capital, enabling them to put innovative research ideas into practice. They may spend five years working on research projects at an institute of their own choice, untroubled by administrative constraints. Furthermore, building up their own working groups allows the award winners to lay important foundations for a promising research career at a very early stage. The programme is funded by the Federal Ministry of Education and Research.

Scientists and scholars of all disciplines from abroad with outstanding qualifications, who have completed their doctorates within the last six years, are eligible to apply. The programme is also open to German academics working abroad. Applications must be submitted by 15 October 2009.

We should be very grateful if you would help us to search for international research talents. For example by disseminating the announcement at your institution or asking researchers you know to draw the attention of junior researchers who might be potential candidates to the award. Details of the application procedure for the Sofja Kovalevskaja Award can be found on our website at http://www.humboldt-foundation.de/SKP_en

Please do not hesitate to contact Dr. Oliver Lange (0228-833-274, oliver.lange@avh.de) or Monika Appmann (0228-833-186, monika.appmann@avh.de) if you have any further questions regarding the Sofja Kovalevskaja award.

With many thanks for your support and kind regards,

Dr. Georg Schütte

Secretary General

Alexander von Humboldt Foundation

Report on the 12th PSSST Conference held on May 21-22, 2009 in Davao City

2009-05-25T23:23:00.003+08:00

Contributed by Judith Carla P. dela Torre (PhilRice)

The 12^th Annual Meeting and Scientific Conference of the Philippine Society of Soil Science and Technology, Inc. (PSSST) was held at Eden Nature Park, Toril, Davao City last May 21-22, 2009. About 140 members from the different international and local institutions, agencies, and state colleges and universities participated in the said event. With this year’s theme titled “Enhancing Soil Productivity and Environmental Quality”, scientists, researchers, extension workers, and students presented their paper and posters to help in finding solutions to issues like soil erosion, decreasing soil fertility and climate change; and to achieve better soil productivity for our country’s sustainable food production program.

The keynote address on “Rice Science for Food Self-sufficiency” was given by Atty. Ronilo A. Beronio, Executive Director of PhilRice. He discussed the rice self-sufficiency program to be achieved by 2013 and challenged soil scientists to educate farmers on how to make soil productive, to lead and preach the science of managing available farm and soil resources, and to effectively explain the synergistic effects of various fertilizers on plant growth.

The three plenary papers were: (1) Integrated Soil and Crop Nutrient Management for Vegetables in the Southern Philippines by Dr. Christopher Dorahy of ACIAR, Australia; (2) Facts and Myths of Organic and Inorganic Fertilizers by Dr. Cezar P. Mamaril of PhilRice; and (3) Enriched Potting Preparations (EPP) for Various Crops by Dr. Eduardo P. Paningbatan of UPLB.

The technical session was divided into three categories: junior, senior-competing, and senior-non-competing. For the junior category, three PSSST scholarship grantees presented their undergraduate thesis and competed for the best paper. At the same time, ten papers /presentations competed for the senior category while five others presented for the non-competing (senior) category. Moreover, 19 posters were presented and judged for the best poster award.

The following recognitions were awarded by Dr. Danilo M. Mendoza, PSSST President and Dr. Cezar P. Mamaril, Advisory Board Member:

Paper/Oral Presentation

Junior Category

Best Paper- Effects of Varying Soil Moisture Levels on the Growth and Development of Lakatan (Musa acuminate Colla.) (Kathy Tafere)

Senior Category

Best Paper – Studying the Effects of Drought on Rice Production in Nueva Ecija Using Remote Sensing Technology (Judith Carla P. dela Torre)

Second Place – Banana Fertilization at the FPO Plantation: Evaluation of Soil and Leaf Analysis Results (Ma. Asuncion L. Salibay)

Third Place – Performance of Bio-fertilizers in Irrigated Lowland Rice presented (Michelle B. Castillo)

Poster Paper

Best Poster – Can we use commercially available fertilizers for Soil NPK test? (Julie D. Elijay, Constancio A. Asis, Jr., and Jesiree Elena Ann P. dela Torre)

Second Place – Fate of Soil Nutrient after Rice Straw Incorporation (Corazon A. Santin, Jesusa M. Rivera and Evelyn F. Javier)

Third Place – PALAYAMANAN Model in Rainfed Rice Ecosystem in Nueva Ecija (Jesusa M. Rivera, Rizal G. Corales, Leylani M. Juliano, Sandro D. Cañete, Ailon Oliver V. Capistrano, Jeny V. Ravis, Jehru C. Magahud, and Madonna C. Casimero)

Continuous cultivation does not always decrease soil organic carbon content

2009-05-22T22:06:00.002+08:00

It is generally known that continuous cultivation causes a decline in soil organic carbon and nutrient contents. This has been shown by many years of research on upland soils starting with the classic study by Nye and Greenland (1960). Our studies in the volcanic mountain of Leyte, Philippines, have also confirmed this (e.g. Asio et al., 1998; Navarrete and Tsutsuki, 2008).

But a recent paper by Benbi and Brar (2009) published in the international journal Agronomy for Sustainable Development does not support this widely held view. In fact, they showed that intensive cultivation increased soil organic carbon by 38 % after 25 years. These researchers evaluated the impact of intensive cultivation of an irrigated and optimally fertilized rice-wheat system in Punjab, India, and found that intensive cultivation enhanced carbon sequestration due to improved crop productivity, greater belowground C transport to the soil and reduced organic matter decomposition during the wetland rice season.

Results of the study also revealed that the rice-wheat cropping in alkaline soils creates a favourable pH environment by lowering soil pH towards neutrality. During the 25-year period, the soil pH declined from 8.8. to 7.7 which resulted in the improvement in nutrient availability. Continuous application of phosphoric fertilizer led to build-up of soil P and the magnitude of accumulation was proportional to the amount of fertilizer applied.

References

Asio V.B., R Jahn, K. Stahr, and J. Margraf. 1998. In: Soils of Tropical Forest Ecosystems (A. Schulte and D. Ruhiyat, eds.). Springer Verlag, Berlin, pp: 29-36.

Benbi D.K. and J.S. Brar. 2009. A 25-year record of carbon sequestration and soil properties in intensive agriculture. Agron. Sustain. Dev. 29: 257-265.

Navarrete IA and K Tsutsuki. 2008. Land-use impact on soil carbon, nitrogen, neutral sugar composition and related properties in a degraded Ultisol in Leyte, Philippines. Soil Science and Plant Nutrition 54: 321-331.

Nye P.H. and D.J. Greenland. 1960. The soil under shifting cultivation. Commonwealth Agricultural Bureau, England.

Organic fertilization improves soil fungi population

2009-05-21T23:54:00.001+08:00

While organic fertilization is now widely known to improve the general soil quality, more data from field experiments are still needed to support this notion. Cwalina-Ambroziak and Bowszys (2009) carried out a 3-year field experiment to determine the influence of organic fertilization on the community of soil fungi as compared to no fertilization and NPK fertilization only. Findings of the study revealed a significantly higher total number of fungal colony-forming units in soil applied with organic fertilizer than in soil without fertilizer application and the one applied with NPK mineral fertilizers. Moreover, pathogen population was highest in soil without fertilization and lowest in the soil added with organic fertilizer.

The study demonstrated that organic fertilization has a positive influence on the structure of soil fungi communities. This was particularly more observable in the qualitative changes in fungi composition than in the changes in fungi numbers. Results of the study support the findings of other researchers that organic fertilization stimulates the growth of soil microorganisms and that it protects the plants against pathogens of the genus Pythium and Phytophthora.

According to Terekhova (2007) fungal communities represent one of the most important functional and structural components of biological systems. Fungi affect the properties of the soil via the regulation of pedogenic processes; the composition of soil organic matter; the soil structure status; the soil acidity; the soil temperature characteristics; and certainly via the regulation of the functioning of soil microbiota.

References

Cwalina-Ambroziak B. and T. Bowszys. 2009. Changes in fungi communities in organically fertilized soil. Plant Soil Environ 55: 25-32.

Terekhova V.A. 2007. The importance of mycological studies for soil quality control. Eurasian Soil Science 40: 583-587.

Leaf decomposition of exotic and native tree species: rates and effect on soil

2009-05-21T16:24:00.001+08:00

Decomposition of organic materials on the forest floor is a vital link between the various components of the forest ecosystem. Through this process, mineral nutrients bound to the biomass are released into the soil and then subject to uptake by plants, fixation by soil components, and losses through leaching and erosion. Decomposition can have considerable influence on the biological and chemical properties of the forest soil depending on the kind of organic material, soil properties, climate, and the availability of decomposers (e.g. Gartner and Cardon, 2004).

Exotic tree species are introduced species from other regions. They are widespread in tropical and subtropical countries since they are popular as reforestation species even in harsh environments (Nyland, 1996) due to their ability to adapt easily to variable site conditions (Weidelt, 1976). Many are considered economically viable because of their fast growth characteristic. Farmers value exotic species more than the native ones because of forestry extension recommendations and desirable cultural attributes (Cromwell and Bradie, 1996). In the Philippines, the most well-known exotic tree species belonging to this group are Mahogany (Sweitenia macrophylla King), Gmelina (Gmelina arborea Roxb.) and Teak (Tectona grandis Linn.).

Native tree species are species which originated from the region where they are growing. Among the more commonly known Philippine native tree species are Bagtikan (Parashorea plicata Brandis), Hagakhak (Dipterocarpus validus Blume) and Narra (Pterocarpus indicus Willd.). The first two species belong to Dipterocarpaceae family, the latter to the Fabaceae.

Presently, there is widespread notion that the use of exotic tree species for reforestation causes negative ecological effects such as soil degradation (Sawyer, 1993). Lindsay and French (2005) cited early studies showing that there are strong positive feedbacks between plant species composition and soil properties such that introduction of a new species can change nutrient cycling and soil properties. It is also believed that native tree species have positive effects on the site. However, very little data exist to support these claims.

We evaluated the effects of incorporation and subsequent decomposition of leaves of exotic tree species (Gmelina arborea, Sweitenia macrophylla and Tectona grandis) and native tree species (Pterocarpus indicus, Dipterocarpus validus and Parashorea plicata) on the quality of forest soil. Forty-two pots filled with an acidic and clayey forest soil and added with fresh leaves of the different tree species were set-up in an open area in Mt. Pangasugan. Retrieval of the first three pots for each treatment was done after two months and the remaining three pots, five months later. Soil samples were collected from each pot and analyzed for pH, OM, total N, available P, and respiration rates.

Our main findings were:

1. Decomposition of the leaves of exotic tree species generally did not change soil pH except that of S. macrophylla which increased soil pH after 5 months. In contrast, the leaves of the native species tended to decrease soil pH particularly in the first two months of decomposition.

2. There was no considerable difference between the effects of the leaves of exotic and those of native tree species on the organic matter and total nitrogen contents of the soil.

3. Available phosphorus content of the soil was significantly increased by the decomposition of leaves of both exotic and native species.

4. The leaves of exotic tree species decompose faster than those of the native species. This finding agrees with that of a separate litter decomposition study by litterbag method conducted at the same site by Aragon (2004).

Source:

Batistel CC and VB Asio. 2009. Effects of leaf decomposition of selected exotic and native tree species on forest soil quality. Annals of Tropical Research (in press)

References

Aragon JA. 2004. Leaf litter decomposition of Dipterocarpus validus Brandis (Dipterocarpaceae) and Gmelina arborea (Verbenaceae) in two forest sites of Mt. Pangasugan. Undergrad Thesis, Leyte State University, Baybay, Leyte. 50 pp.

Cromwell E and A Bradie. 1996. Germplasm for Multipurpose Trees: Access and Utility in Small-farm Communities. ODI London.

Gartner TB and ZG Cardon. 2004. Decomposition dynamics in mixed species leaf litter. Oikos 104: 230-246.

Lindsay EA and K French. 2005. Litterfall and nitrogen cycling following invasion by Chrysanthemoides monilifera ssp. Rotundata in coastal Australia. Journal of Applied Ecology 42: 556-566.

Nyland R 1996. Silviculture (Concepts and Application). McGraw-Hill Co. Inc. Singapore.

Sawyer J 1993. Plantations in the Tropics: Environmental Concerns. IUCN/UNEP/WWWF, Gland, Switzerland.

Weidelt H A 1976. Manual of Reforestation and Erosion Control for the Philippines. German Agency for Technical Corporation LTD (GTZ) Germany.

PSSST holds 12th national scientific conference

2009-05-18T20:32:00.002+08:00

The Philippine Society of Soil Science and Technology (PSSST), the country’s national professional organization of soil scientists and soil practitioners, is holding its 12^th Annual Meeting and Scientific Conference on 20-23 May 2009 at Eden Nature Park and Resort, a beautiful man-made resort on the slopes (about 800 m asl) of Mount Talomo, Toril, Davao City.

The conference which aims to meet the challenges in enhancing soil productivity and environmental quality, reflects the state of the art of soil research, development, extension and policy support in the Philippines. It provides an excellent forum for the exchange of research findings and scientific ideas among established and young soil scientists and soil practitioners working at the various universities, colleges, research centers, and government agencies.

I wish to congratulate the officers led by Dr. Danny Mendoza and the members of the society for organizing this very important activity. I hope most members will be able to attend despite the difficult economic situation we are all in right now.

One person deserves a special mention: Dr. Neo Manguiat. It's largely because of his guidance and support that PSSST has been very successful as a professional organization.

The current PSSST officers are: Dr. D.M. Mendoza, President; Ms. C.G. Mangao, Vice-President; Dr. V.M. Padilla, Secretary; Ms. C.D. Bacatio, Tresurer; Dr. P.P. Juico, Auditor; Dr. C.A. Asis, Jr., PRO; Ms. R.N. Atienza, Business Manager; Ms. E.F. Javier, Dr. C.P. Laurea, Dr. E.P. Paningbatan, Jr., Dr. P.B. Sanchez, Mr. M.M. Marquez, Board Members; and Dr. C.P. Mamaril and Dr. I.J. Manguiat, Advisers. Ms. B.C. Magno, Ms. A.C. Marca, and Ms. A.T. Guy, Liaison Officers.

Are the tropical soils in Southeast Asia unique?

2009-05-17T21:49:00.004+08:00

The soils in the tropical islands of SE Asia may be distinct from those in other tropical areas like Africa and the

Americas

because of the unique environmental factors that influenced their formation (Asio et al., 2006; Navarrete et al., 2007). Geologically, much of SE Asia was the result of recent tectonic event and many areas emerged from the sea recently (Hall, 2002). Consequently, it is much younger than Africa and Central and South America. In terms of climate, SE Asia is also different from the other regions. During the drier period of the Quaternary, the effects of climatic changes in landform development were unique because large areas were under the regime of the monsoonal system (Verstappen 1997). Chang et al. (2005) reported that the present climate that prevails in SE Asia is also unique since it is located in the transitional region between the boreal summer Asian monsoon and the boreal winter Asian monsoon. In terms of the soil-forming factor organisms (flora and fauna), biodiversity is high in the region (Myers et al., 2000) because of the effect of climate and geological history (Nakashizuka 2004). Heemsbergen et al. (2004) reported that biodiversity is related to soil processes. Land use systems and soil management practices of farmers in SE Asia are also different from those in other tropical regions suggesting that the influence of man as a factor of soil formation maybe different from farmers in other tropical areas.

References

Asio VB, CC Cabunos, ZS Chen. 2006. Soil Science 171: 648-661.

Chang CP, Z Wang, J McBride, CH Lieu. 2005. J. Climate 18: 287-301.

Hall R. 2002. J. Asian Earth Sci. 20: 353-431.

Heemsbergen DA, MP Berg, M Loreau, JR Van Hal, JH Faber, HA Verhoef. 2004. Science 306: 1019-1020.

Nakashizuka T. J. 2004. J. For. Res. 9: 293-298.

Navarrete, IA, VB Asio, R Jahn, K Tsutsuki. 2007. Australian J. Soil Research 45: 153-163.

Verstappen H.Th. 1997. J. Quaternary Sci. 12: 413-418.

Weathering of basalt and clay mineral formation in Leyte, Philippines

2009-05-17T18:21:00.003+08:00

Weathering is the physical, chemical, and biological alteration of minerals in rocks, sediments, and soils at or near the Earth’s surface. It is an important link in the global rock cycle and is also an essential process for the formation of soils and landforms. Chemical weathering of silicate minerals which compose over 90% of the Earth’s crust, removes CO₂ from the atmosphere so it helps regulate the Earth’s climate over long time scales. Basalts are among the more easily weathered crystalline rocks thus, weathering of these rocks acts as a major CO₂ sink. Chemical weathering of rocks likewise releases nutrient elements for use by the biota in the ecosystem and also produces clay minerals which are the central components of soils.

We studied the weathering of basalt by evaluating the gain and loss of elements, stream water composition, weathering indices, and clay mineral formation in the soil derived from basalt under the humid tropical conditions (average annual rainfall of 2700 mm and average temperature of 28^oC) in Leyte, Philippines. The study site is located in the rain forest on the lower western slope of Mt. Pangasugan having an elevation of 100 m asl. The weathering profile studied is about 4 meters deep, heavy clay, acidic and yellowish red soil classified as Alisol (or Ultisol).

Results revealed that much of the basic cations Ca, Mg, K, Na and part of Si have already been lost from the weathering product (saprolite and soil). This was however accompanied by the accumulation of Al, Fe, C, and H2O. The extent of weathering as indicated by the loss of elements based on the total elemental composition of fresh rock and of saprolite and soil was closely related to the cation composition of the stream water in the study site. Relative rates of loss of bases and silica revealed the sequence: Ca>K>Na>Mg>>Si for the soil, and Ca>Na ≥ Mg>K for the stream water. The ratio Na : (Na+Ca) of the stream water indicated that its major source of cations was rock weathering.

Results also showed that the intensive basalt weathering has resulted in the formation and abundance of kaolinite and halloysite clay minerals (see above TEM micrograph) as well as goethite in the highly weathered soil. The idea that weathering moves to a system composed of SiO₂, Al₂O₃, Fe₂O₃, and H₂O (residua hypothesis of Chesworth) appears to be supported by the results of this study.

Reference
Asio VB and R Jahn. 2007. Weathering of basalt and clay mineral formation in Leyte, Philippines. Philippine Agricultural Scientist 90 (3): 204-212.

Soil distribution in the Philippines

2009-05-15T17:39:00.005+08:00

The distribution of soils in the Philippines is largely controlled by parent material, relief, and vegetation. In general, Philippine soils are younger than the tropical soils in mainland Asia, Central and South America, and Africa. This is because most Philippine islands are geologically young since they were the result of, just like much of Southeast Asia, recent Cenozoic tectonic events and have emerged from the sea recently (Hall, 2002).

Philippine soils maybe grouped based on geomorphology and for practical purposes, into: soils in lowland areas, soils in young and unstable uplands, and soils in old and stable uplands.

Soils in lowland areas

Lowland areas include all flatlands located near sea level. Most of these areas are underlain by recent alluvial sediments. Because of this and due to periodic deposition of sediments during flooding events, the soils in lowland areas are poorly developed.

Arenosols (Entisols). These are weakly developed sandy soils common in alluvial plains andcoastal areas.
Gleysols (Entisols, Inceptisols). These are the poorly developed wet soils in alluvial plains and marshes. They are used chiefly for lowland rice production. Together with Histosols, Gleysols are the dominant soils of wetlands.
Cambisols (Inceptisols). These are weakly developed soils showing poor horizon B development. They occur in association with Gleysols although they can also be found in mountainous areas.
Fluvisols (Entisols). These are the undeveloped soils commonly found along rivers. Periodic deposition of river sediments retard soil development.
Vertisols (Vertisols). These are the clayey soils in lowland areas that produce large cracks on the surface during the dry season. They are very fertile and are widely used for lowland rice production. A typical example can be found in Mangaldan, Pangasinan.
Histosols. These are found in swamps, marshes, shallow lakes, and depressions. The saturated condition favors the accumulation of organic materials. Large areas are found in Leyte, Samar and Surigao.

Soils in young and unstable uplands

Uplands are undulating as well as hilly lands ranging in elevation from near sea level to about 1000 meters. Many upland areas around the country are the result of recent volcanic activity or geologic uplift. These are young landscapes underlain by young volcanic deposits or reef limestone and thus have also poorly developed soils.

Leptosols (Entisols, Inceptisols). These are the shallow soils (less than 50 cm deep) in rocky areas. Many soils derived from limestone in various islands have very thin solum and thus they belong to Leptosols.
Andosols (Andisols). These are the poorly developed soils on young volcanic landscapes in the mountains of Negros, Leyte, Bicol, Taal and other volcanic areas of the country. The soil is soft and very friable and appears dark due to the high organic matter content. Except for their very low P availability, the properties of these soils are generally favorable for crop production.
Chernozems (Mollisols). These are very fertile soils due to their organic matter-rich topsoil. They can be found in limestone areas in Leyte, Bohol and other islands.

Soils in old and stable uplands

Old uplands were formed by volcanism or geologic uplift millions of years ago. They typically occur on the lower slopes of volcanic mountains. Soils in these areas are well-developed or highly weathered.

Ferralsols (Oxisols). These are the very deep, red, acidic and very infertile soils found in old landscapes in Palawan, Mindanao, and Samar.
Acrisols and Alisols (Ultisols). These are the reddish, clayey, acidic soils widespread in hilly and mountainous areas throughout the archipelago.
Luvisols (Alfisols). These are the well-developed soils with high base saturation (fertile) found in old alluvial terraces in various areas in the Philippines.

(Photo above shows the typical soil-landscape relationship in the volcanic island of Leyte)

References

Asio VB. 1996. Characteristics, weathering, formation and degradation of soils from volcanic rocks in Leyte, Philippines. Hohenheimer Bodenkundliche Hefte vol. 33, Stuttgart.

Asio VB, PP Garcia, GAA Garcia. 2005. Development of a new soil map of Leyte. Unpublished project report, VSU, Baybay, Leyte.

Barrera A, F Aristorenas, JA Tingzon. 1954. Soil survey of Leyte province, Philippines. Soil Survey Report No. 18, Bureau of Print, Manila.

Bureau of Soil and Water Management (undated). Soil map of the Philippines (1:7,500,000). http://www.fap.org/ag/AGL/swlwpnr/reports/y_ta/z_ph/phmp231.htm#s133.

Hall R. 2002. Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: model and animation. J. Asian Earth Sci. 20: 353-431.

Hirayama R, R Carating, T Ohkura, V Castaneda, M Vinluan. 2002. The soils of the Philippines. Proc. 3rd and 4th symposia on collection building and natural history studies in Asia and the Pacific Rim (T Kubodera et al., eds). National Science Museum Monographs 22: 109-113.

Concentration affects plant uptake of inorganic and organic forms of N

2009-05-14T17:19:00.002+08:00

It is now recognized that plants take up N from the soil in three forms: nitrate, ammonium, and amino acids (dissolved organic N). Although scientific evidence on plant uptake of amino acids has existed in the last few decades, it is only recently that the contribution of amino acids to plant nutrition has been recognized (see Warren 2009 and literatures cited). So the traditional view that organic N has to be mineralized first into nitrate and ammonium in order to be available to the plant is not anymore valid.

Different plant species vary in their preference for N forms. For instance, early successional plant species are known to have a higher capacity for nitrate uptake than late successional species. Uptake of N in the form of ammonium and amino acids is thus more important for the latter species. In a recent study to test the hypothesis that substrate concentration affects plant preference for N forms, Warren (2009) used the herb Ocimum basilicum and the evergreen tree Eucalyptus regnans. He placed roots of intact seedlings in equimolar mixtures of nitrate, ammonium and glycine (amino acid). His results revealed that substrate concentration influenced the preference of both plants for N forms. This means that whether the plant prefers one N form over another (e.g. nitrate over ammonium and amino acid or vice versa) depends on their concentrations in the growth medium or soil.

Reference

Warren CR. 2009. Does nitrogen concentration affect relative uptake rates of nitrate, ammonium, and glycine? J. Plant Nutr. Soil Sci. 172: 224-229.

Effects of elevation on N cycling in tropical forests

2009-05-13T20:37:00.003+08:00

Scientists predict that tropical regions will receive the most dramatic increase in nitrogen (N) deposition over the next decades. This is due to increased fertilizer use, legume cultivation, fossil fuel consumption and biomass burning. There is thus a need for a better understanding of N cycling in tropical forest ecosystems. In a recent study by Arnold et al. (2009) across an Andosol (young volcanic ash soil) toposequence in Ecuador (Equitorial South America), it was revealed that gross rates of N transformations, microbial N turnover time, and δ¹⁵ N signatures in soil and leaf litter decreased with increasing elevation, indicating a decreasing N availability across the toposequence. Accompanying the above-mentioned trend was a decreasing degree of soil development with increasing elevation as indicated by declining clay content, total C, total N, effective cation exchange capacity and increasing base saturation. The study also revealed that soil N-cycling rates and δ¹⁵ N signatures were highly correlated with mean annual temperature but not with mean annual rainfall. Microbial immobilization was the largest fate of produced NH₄⁺ whereas nitrification activity was only 5-11% of gross NH₄⁺ produced. A fast reaction of NO₃^- to organic N which suggests abiotic NO₃^- immobilization, was also observed.

Reference

Arnold J, Corre MD, Veldkamp E. 2009. Soil N cycling in old-growth forests across an Andosol toposequence in Ecuador. Forest Ecology and Management 257: 2079-2087.

Relation between nutrient status of rainforest trees and environmental factors

2009-05-13T16:53:00.002+08:00

The mineral nutrition of native plant species is still poorly understood. This is particularly true for the various tree species in rain forest ecosystems. In order to evaluate the mineral nutrient status of the dominant tree species and its relation to environmental factors such as elevation, slope, landscape position, and soil nutrient status, Z.S. Chen and co-workers (Wu et al., 2007) collected leaf, stem, and wood samples for nutrient analysis from a total of 636 trees belonging to 20 dominant species from 27 contiguous 20m x 20m quadrants along an altitudinal transect in a subtropical rain forest in southern Taiwan. They also collected composite soil samples from the 0-5 and 5-15 cm depths in each quadrant for chemical analysis.

Their results revealed that leaf concentration was better correlated with the environmental factors than stem and wood nutrient concentrations. This means that leaf analysis is more appropriate than stem and wood analyses to evaluate the nutrient status of native tree species. They also found wide concentration ranges for most mineral nutrients except P and Cu and most tree species were clustered at the lower end of the concentration ranges indicating they have low nutrient status. Among the macronutrients, P had the lowest and narrowest foliar concentration (0.25-2.8 g kg^-1) confirming the results of other studies from other tropical areas that P is the most limiting nutrient in tropical ecosystems. For the micronutrients, the lowest concentration was shown by Cu (3.88-17 mg kg^-1). A few tree species were found to accumulate (called “accumulator species”) nutrients like N, P, K, Ca, Mg, Cu and Zn indicating high absorption capacity for these nutrients. Foliar mineral nutrient concentration of the trees was generally correlated with the environmental factors such as elevation, topographic position, slope, vegetative type and soil nutrient status.

Reference

Wu CC, Tsui CC, Hseih CF, Asio VB and Chen ZS. 2007. Mineral nutrient status of tree species in relation to environmental factors in the subtropical rain forest of Taiwan. Forest Ecology and Management 239: 81-91.

Nitrate and phosphate leaching from Lake Danao soil (Leyte, Philippines)

2009-05-12T02:26:00.002+08:00

Nitrogen and phosphorus are the most important nutrients that also function as environmental pollutants (Logan, 2000). The natural levels of these nutrients in soils are not high enough to cause environmental pollution. But the heavy and long-term use of chemical and organic fertilizers can lead to leaching of nitrate (NO₃^-) and phosphate (PO₄^3-) from the soil and thereby result in the contamination of the groundwater as well as of nearby surface waters such as rivers and lakes (e.g. Scheffer and Schactschabel, 1992; Logan, 2000). High nitrate level in surface waters contributes to fish kills and makes the water unsafe for animal and human consumption. Increased phosphate concentration in surface waters leads to eutrophication since phytoplankton in these waters respond to increased P level since it is a major limiting nutrient in fresh water ecosystems (Logan, 2000; Toor et al., 2003). The resulting accelerated growth of water plants and general degradation of water quality, limit the use of the affected surface waters for fisheries, recreation, industry and drinking (Lal and Stewart, 1994). According to WHO (1993) drinking water contamination with nitrate is presently the environmental issue of greatest concern in N management.

Lake Danao (also called Imelda Lake in former times) is a natural lake with an area of 1.9 km² in the form of guitar located at 700 m above sea level (ASL) in the central highlands of Leyte, Philippines (see photo). Surrounded by mountains with young loamy volcanic soils (Andisols), the lake provides water for home consumption and industrial uses, and opportunities for livelihood of people living nearby. It is a national reserve and popular tourist attraction due to its beautiful scenery and generally cooler climate than the lowlands of Leyte. In a recent Lake Danao watershed management study which was part of a VSU-Cornell University collaborative research and funded by USAID-ALO, it was revealed that there has been increasing signs of ecological degradation of the lake ecosystem in the last decade (Garcia et al., 2005). For example, many areas on the mountain slopes around the lake have been converted into agricultural farms which often use fertilizers and pesticides. Detergents used in households in the community on the bank of the lake can contribute substantial amount of P to the lake through leaching.

Until now there is lack of published data on the capacity of Philippine soils to filter pollutants as well as on the environmental impacts of the application of chemical and organic fertilizers to soils bordering surface water bodies like lakes and rivers. According to Sharpley et al. (2003) leaching of P is generally low except in sandy, acid organic, or peaty soils with low P fixation capacity and in soils where the preferential flow of water can occur rapidly through macropores and earthworm holes. Toor et al. (2003) observed that P leaching occurs in grassland soil largely in the form of organic P. Considering that the Lake Danao soil has very high porosity and organic matter content, it was thought that addition of fertilizers may enhance not only nitrate leaching but phosphate leaching as well despite of it being an Andisol.

In view of the above a laboratory study was conducted to find out if Lake Danao soil allowed leaching of nitrate and phosphate after addition of chemical fertilizers and manure. The leaching experimental set-up was designed and constructed using PVC cylinders containing the Lake Danao soil and amended with various amounts of poultry manure and chemical fertilizers like urea and solophos. The treatments were based on the application rate employed by the farmers around the lake. Results revealed that high amount of nitrate was leached from the soil amended with urea but only small amount in soil added with poultry manure. Findings also showed low amount of phosphate that was leached from the soil amended with either poultry manure or chemical fertilizer. Although field verification of the results maybe necessary, the study implies that the practice of using urea by the farmers can lead to eutrophication of the nearby lake. The use of poultry manure as fertilizer will minimize the said environmental effects.

Source:

Magahud JC and VB Asio. 2009. Nitrate and phosphate leaching from Lake Danao Andisol treated with manure and chemical fertilizer. Paper presented during the National Scientific Conference of the Philippine Society of Soil Science and Technology (PSSST), 20-23 May 2009, Davao City, Philippines.

References

Garcia P.P., E.A. Saz, V.B. Asio, T.A. Patindol and Z.M. de la Rosa. 2005. Multisectoral watershed planning in Lake Danao Natural Park through participatory approaches. Final Project Report, LSU-Cornell University ALO Project, 61pp.

Logan, T.J. 2000. Soils and environmental quality. In: Handbook of Soil Science (M.E. Sumner, ed.). CRC Press, Boca Raton, pp: G155-G169.

Scheffer F. and P. Schachtschabel. 1992. Lehrbuch der Bodenkunde. (13th ed.). Ferdinand Enke Verlag, Stuttgart, 491pp.

Sharpley AN, T Daniel, T Sims, J. Lemunyon, R Stevens, R Parry. 2003. Agricultural phosphorus and eutrophication. 2nd ed. USDA-ADS, ARS-149, 44pp.

Toor G.S., L.M. Condron, H.J. Di, K.C. Cameron and B.J. Cade-Menun. 2003. Characterization of organic phosphorus in leachate from a grassland soil. Soil Biol. Biochem.5: 1317-1323.

World Health Organization. 1993. Guidelines for Drinking Water Quality, Volume 1. Recommendations. Second Edition. WHO Geneva. 110 pp.

The original Handbook of Soil Science

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One of the most influential books on soil science in the 20^th century was the Handbuch der Bodenlehre (Handbook of Soil Science), a 10-volume book edited by Professor E. Blanck of the University of Göttingen, Germany, and published by Verlag von Julius Springer, Berlin, from 1928-32 (see photo). The book presented the state of the art in soil science until the late 1920s. According to the prominent soil scientist Professor Dan Yaalon of Hebrew University, modern soil research took off at an accelerated rate as a result of the publication of this monumental book by Blanck (Yaalon and Berkowicz, 1997). The contents of the different volumes are as follows: Volume 1- The Natural Science Principles of the Origin of Soils; Volume 2- The Climatic Principles of the Formation and Weathering of Soils; Volume 3- The Distribution of Soil types on the Earth’s Surface, Regional and Zonal Soil Science; Volume 4- Non-climatic Soil Formation, the Soil Forms in Germany and Fossils Weathering; Volume 5- The Soil as the Topmost Layer of the Earth’s Surface and its Geographic Importance; Volume 6- The Physical Properties of Soils; Volmue 7- The Chemical and Biological Properties of Soils; Volume 8 and 9- Applied or Special Soil Science (Soil Technology); Volume 10- The Methods of Cultivating Soils. Although Prof. Blanck was the main editor, he was assisted by a team of editors which was responsible for each volume. Each volume consisted of several chapters contributed by different authors. Prof. Hans Jenny who was still in Zurich at the time contributed a chapter on high mountain soils which appeared in Volume 3.

(A complete set of this handbook is found in the library of the Soil Science and Soil Protection Division, Institute of Agricultural & Nutritional Sciences, Faculty of Natural Sciences III, University of Halle-Wittenberg, Germany)

Reference:

Yaalon, D.H. and S. Berkowicz. 1997. History of Soil Science-international perspectives. Advances in Geoecology 29, Catena Verlag, 438pp.

The importance of N:P ratio

2009-05-09T17:21:00.001+08:00

Soil fertility in terrestrial ecosystems has received increased attention from ecologists since it is now widely recognized that nutrient availability drives ecosystem functioning and processes (Wardle and Zackrisson, 2005). N and P are believed to be the most limiting nutrients in many terrestrial ecosystems particularly forests. Availability of N and P vary considerably during soil development as P is lost through leaching and fixation while N accumulates through biological N fixation (Walker and Syers, 1976; Crews et al., 1995). Thus, young soils have the tendency to be N limited while old soils are P limited. Ecosystem studies have confirmed this relationship of N and P indicated by the N:P ratio. It has been found that the leaf N:P ratio can detect nutrient limitation for wetland terrestrial ecosystem. An N:P ratio >16 indicates P limitation which is in clear agreement with the Redfield ratio (Redfield, 1958) for marine ecosystems. An N:P ratio <14 indicates N limitation and between 14 and 16 means either N or P is limiting (Koerselman and Meuleman (1996). It has also been reported that P limitation relative to N is widespread in terrestrial ecosystems (Elser et al., 2000a and 2000b) and that it is the cause of biomass decline in forest ecosystems in strongly weathered soils (Wardle et al., 2004a). Kitayama (2005) argued, however, that despite P limitation, tropical rain forests in Southeast Asia are still able to maintain high biomass as a result of high species diversity.

Elemental stoichiometry or the ratio of key elements such as carbon (C), nitrogen (N), and phosphorus (P) in organisms is useful in analyzing how the organisms influence or is being influenced by the ecosystem in which they are found (Elser and Dobberfuhl, 1996). While the elemental stoichiometry (Redfield ratio) of 106 C: 16 N: 1P is well-established for marine ecosystems it is just starting to be applied to terrestrial ecosystems. Thus, Elser and Urabe (1999) suggested that scientists working in other ecosystems (e.g. forest) might profitably apply stoichiometric approaches to food web dynamics and nutrient cycling. This is particularly valid for terrestrial systems since autotroph biomass N:P in terrestrial and freshwater systems has been found to be closely similar (Elser et al., 2000b)

References

Crews T.E et al. 1995. Changes in soil phosphorus fractions and ecosystem dynamics across a long chronosequence in Hawaii. Ecology 76: 1407-1424; Elser, J.J., Dobberfuhl, D.R., 1996. Organism size, life history, and N:P stoichiometry. Bioscience 46, 674-685; Elser, J.J. et al. 2000a. Biological stoichiometry from genes to ecosystems. Ecology Letters 3, 540-550; Elser, J.J, et al.2000b. Nutritional constraints in terrestrial and freshwater food webs. Nature 408, 578-580; Kitayama, K., 2005. Comment on ecosystem properties and forest decline in contrasting long-term chronosequences. Science 29, 633b; Koerselman, W., Meuleman, A.F.M., 1996. The vegetation N:P ratio: a new tool to detect the nature of nutrient limitation. Journal of Applied Ecology 33, 1441-1450;Redfield, A.C., 1958. The biological control of chemical factors in the environment. Am. Sci. 46, 205-221; Wardle, D.A., Zackrisson, O., 2005. Effects of species and functional group loss on island ecosystem properties. Nature 435:806-810;Warlde, D.A et al.2004a. Ecosystem properties and forest decline in contrasting long-term chronosequences. Science 305:509-513; Wardle, D.A. et al. 2004b. Ecological linkages between aboveground and belowground biota. Science 304: 1629-1633.

Relation between N mineralization and latitude

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The global distribution of soils is a function of climate and thus is related to latitude. Consequently, soil processes are known to vary with latitude. But a recent study by Jones et al. (2009) which used soils collected from 40 latitudinal points from the Arctic through to Antarctica, showed that this is not the case for key soil processes like the turnover of amino acids (amino acids represent a key pool of carbon and nitrogen in soil and their availability to plants and microorganisms is considered a major driver in regulating ecosystem functioning). They found that “soil solution amino acid concentrations were relatively similar between sites and not strongly related to latitude. In addition, when constraints of temperature and moisture were removed, they demonstrated that soils worldwide possess a similar innate capacity to rapidly mineralize amino acids. Similarly, they showed that the internal partitioning of amino acid-C into catabolic and anabolic processes is conservative in microbial communities and independent of global position. This supports the view that the conversion of high molecular weight (MW) organic matter to low MW compounds is the rate limiting step in organic matter breakdown in most ecosystems.”

Reference

Jones DL, K Kielland, FL Sinclair, R A Dahlgren, KK Newsham, JF Farrar, DV Murphy. 2009. Soil organic nitrogen mineralization across a global latitudinal gradient. Global Biogeochem. Cycles, 23, GB1016, doi:10.1029/2008GB003250

Fate of nitrate in the capillary fringe and shallow groundwater

2009-05-09T00:13:00.002+08:00

Nitrate pollution of groundwater systems is a serious problem in many countries. Application of nitrogen-containing fertilizers to irrigated crops is widely known as the major cause of nitrate pollution in groundwater systems. Nitrate is assumed to move downward through the vadose zone (unsaturated zone) and then move horizontally in the groundwater. But a recent study revealed that this may not be the case. Abit et al. (2008) evaluated the fate of nitrate in the capillary fringe (i.e. the subsurface layer at the boundary between the vadose zone and the zone of saturation) and shallow groundwater for a sandy soil with shallow water table. They found that nitrate entered the capillary fringe from the unsaturated zone then moved horizontally in the capillary fringe until it was partially carried into the groundwater by the fluctuating water table following rain events.

Reference

Abit SM, Amoozegar A, Vepraskas MJ, Niewoehner CP. 2008. Fate of nitrate in the capillary fringe and shallow groundwater in a drained sandy soil. Geoderma 146: 209-215.

Land use change decreases carbon, nitrogen, and sugar contents of tropical soil

2009-05-07T22:22:00.004+08:00

Land use change is an important ecological driver in the Philippines and other parts of the tropics. It is the major cause of the widespread occurrence of degraded lands in this humid tropical country.

Navarrete and Tsutsuki (2008) investigated the effects of land use change in Mt. Pangasugan in Leyte. They found that conversion of forest into secondary land uses like mahogany plantation, rainforestation farm (a form of reforestation using native tree species in combination with fruit trees and some shade-loving crops), coffee plantation, and grassland decreased the soil carbon, nitrogen, and non-cellulosic neutral sugar (mainly arabinose and xylose) contents of the soil. Within land-use type, differences in the above-mentioned soil parameters could be attributed to differences in the vegetation cover, past land use, and the succeeding soil management after land use change. Their findings also revealed that the grassland and rainforestation farm (which was also a former grassland) had the lowest non-cellulosic sugar content while the secondary forest had the highest.

Reference
Navarrete IA and K Tsutsuki. 2008. Land-use impact on soil carbon, nitrogen, neutral sugar composition and related properties in a degraded Ultisol in Leyte, Philippines. Soil Science and Plant Nutrition 54: 321-331.

Clay minerals in soil have antibacterial properties

2009-05-07T21:47:00.002+08:00

Clay minerals are a major component of soils. They are an important source of negative charge which enable the soil to hold nutrients and pollutants. In recent years, the medicinal effect of clay minerals has gained increased interest among medical researchers.

In a recent paper in the Journal of Antimicrobial Chemotherapy, Haydel et al. (2008) reported:
"The capacity to properly address the worldwide incidence of infectious diseases lies in the ability to detect, prevent, and effectively treat these infections. Therefore, identifying and analyzing inhibitory agents are worthwhile endeavors in an era when few new classes of effective antimicrobials have been developed. The use of geological nanomaterials to heal skin infections has been evident since earliest recorded history, and specific clay minerals may prove valuable in the treatment of bacterial diseases."

The researchers found that specific clay mineral products have antibacterial properties which have potential to treat numerous human bacterial infections.

Reference
Haydel SE, CM Remenih, and LB Williams. 2008. broad-spectrum in vitro antibacterial activities of clay minerals against antibiotic-susceptible and antibiotic-resistant bacterial pathogens. J. Antimicrob. Chemother. 61: 353-361.

Effects of warfare on soil development

2009-05-07T21:09:00.002+08:00

The influence of the physical environment on the outcome of battle is well-known but not the effects of warfare upon the environment particularly the soil. In view of this Hupy and Schaetzl (2008) studied the WWI battlefield of Verdun, France (1916). The battlefield which encompasses an area of 29,000 km², remains one of the most heavily shelled of all time. Their findings revealed that many craters penetrated the shallow limestone bedrock, and blasted out fragments of limestone found on nearby undisturbed soils had already been incorporated into the soil profile. Although the battle happened less than a century ago (88 years), weathering and pedogenesis have already occurred in the soils within the craters. A major pedogenic process noted by the researchers is the accumulation and decomposition of organic matter, which is intimately associated with (and aided by) earthworm bioturbation (soil mixing). The study shows that warfare can cause dramatic changes in the soil and landscape. It also "provides insight into the ability of a landscape to recover following a catastrophic anthropogenic disturbance” wrote Hupy and Schaetzl.

Reference:

Hupy JP and RJ Schaetzl. 2008. Soil development on the WWI battlefield of Verdun, France. Geoderma 145: 37-49

The "home field advantage" in plant litter decomposition

2009-05-07T20:51:00.002+08:00

If you collect leaf litter from a Mahogany plantation and put it beaneath Gmelina trees or vice versa, the rate of litter decomposition will not be the same. According to a recent paper by Ayers et al. (2009), leaf litter decomposition is faster beneath the plant species from which the litter had been derived than beneath a different plant species. This is called home-field advantage. The authors observed that home-field advantage is widespread in forest ecosystems and hypothesized that this is due to the specialization of the soil organisms in decomposing litter derived from the plant above it. In other words, soil organisms living beneath the Mahogany trees are specialized in decomposing the leaf litter from this tree species.

Reference: Ayers E et al. (2009). Home-field advantage accelerates leaf litter decomposition in forests. Soil Biology and Biochemistry 41: 606-610.

Soil and human health

2009-05-07T16:33:00.002+08:00

People living in areas with fertile soils are better nourished than those living in degraded soils due to the higher quantity and quality of food in the former than the latter. Likewise, people living in polluted environments are more exposed to the ill effects of pollutants. The paths of environmental contaminants leading to humans are the following (Logan, 2000):
a) Soil-> crop-> human
b) Soil-> crop-> livestock-> human
c) Soil-> crop-> livestock-> human
d) Soil-> surface waters-> fish-> human
e) Soil-> groundwater-> human
f) Soil-> air-> human
g) Soil-> human

The pathways a to e are indirect links between soil and human health and are relatively well-known. The pathways f and g are direct links and are little known and understood.

Direct links between soils and human health & geophagy

Humans ingest soil either involuntarily or deliberately. For the involuntary ingestion, every person ingests at least small quantities of soil. This is because any soil adhering to the skin of fingers may be inadvertently taken in by hand-to-mouth activity. This is especially true for children who like to play outdoors and for people working outside buildings or in the fields. Soil is also an important constituent of household dust and many foods such as fruits, vegetables and tubers crops usually contain some soil particles especially in poor countries. It is estimated that an average adult ingests soil at a rate of 10 mg per day.

Geophagy is the deliberate ingestion of soil by humans and animals. It is practiced by different peoples in all continents but is most common in the tropics particularly in Africa. This phenomenon was already known in the ancient world but the first detailed scientific report about it was written by the great German naturalist and founder of geography Alexander von Humboldt during his expedition of 1799-1804 to South America. Von Humboldt observed that eating soil was practiced by the indigenous Ottomac people in the Orinoco in Venezuela. The reasons for geophagy are still being debated until now but are known to vary from place to place. These include: soil as famine food to appease the pangs of hunger, as medicine and therapeutic (recent research has shown that clay adsorbs and detoxifies toxins and has antimicrobial action), cravings and good taste especially for pregnant women, as source of mineral nutrients to correct deficiencies, and an abnormal appetite for non-food substances. But excessive soil intake can lead to death of an individual due to the toxic effects of some mineral elements like Fe. This is likely to happen if the soil is contaminated with pollutants. Ingesting soil can also cause ingestion of eggs of parasitic worms and other disease-causing organisms (Abrahams, 2002; Dominy et al., 2004).

Another direct link between soil and human health occurs through inhalation. People inhale soil dusts inside their houses and by just walking in the street. The amount of inhaled dusts under normal conditions is generally low and thus is not harmful. But very dusty environments can cause lung problems. Also inhalation of even small amounts of the fibrous dust of serpentine and amphibole minerals commercially called asbestos is dangerous in that it can cause diseases and even cancer.

References

Abrahams, P.W. 2002. Soils: their implications to human health. The Science of the Total Environment 291: 1-32.

Dominy N.J., E. Davoust, and M. Minekus. 2004. Adaptive function of soil consumption: an in vitro study modeling the human stomach and small intestine. Journal of Experimental Biology 207: 319-324.

Logan, T.J. 2000. Soils and environmental quality. In: Handbook of Soil Science (M.E. Sumner, ed.). CRC Press, Boca Raton, pp: G155-G169.

Soil as component of landscapes and ecosystems

2009-05-07T15:51:00.001+08:00

Landscape is a three dimensional section of the Earth’s surface with specific pattern of topography, rocks, soil, water and flora and fauna. E. Schlichting (1923-1988) proposed that soils in different positions in the landscape (or catena) exchange materials through transport processes which could be compared to the transfer processes between horizons in a soil profile (Schlichting, 1964). Landscape pedology is an emerging science focusing on soil as part of the landscape particularly on the variability of soil properties at the landscape scale (1-10km) (Sommer, 2006).

Ecosystem is a natural system consisting of a biosystem (community of organisms) interacting with the geosystem (its physical environment). The geosystem includes soil, water, relief, and climate. Soil is a major component of geosystem in that it provides nutrients, water and living space to the organisms in the ecosystem. Two emerging fields of science are ecopedology and geoecology. The former focuses on the ecological role of soil while the latter on the geosystem (soil, rock, water) component of ecosystems.

The two major types of ecosystems are the terrestrial ecosystem (or ecosystem on land) and aquatic ecosystems. In the humid tropics, a common landscape consists of the following terrestrial ecosystem types: forest, agricultural (agro-ecosystem), wetland, urban and mangrove. All the terrestrial ecosystem types are linked by the soil. The transfer of water, nutrients and soil material occurs largely in the soil. The soil also determines to a great extent the biological system that develops in each terrestrial ecosystem type. Further, degradation of the soil in the terrestrial ecosystem also affects the health of the aquatic ecosystem nearby. For instance, in many places in the Philippines, severe soil erosion in the uplands causes heavy siltation of the nearby marine area and thus affecting the survival of marine organisms.

References

Schlichting, E. 1964. Einführung in die Bodenkunde. Verlag Paul Parey, Hamburg, 93pp.

Sommer M. 2006. Influence of soil pattern on matter transport in and from terrestrial biogeosystems- a new concept for landscape pedology. Geoderma 133: 107-123.

Functions of soil

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Soil is not dirt. It is a vital life-support system for human survival. Below are the major functions of soil:

a) Production function. Soil acts primarily as a medium for the growth of natural vegetation and cultivated plants. It assures the supply of food, fodder, renewable energy and raw materials. This is also referred to as the forestry and agricultural function of the soil.

b) Ecological regulator. Soil acts as filter, buffer, and transformer of various substances in or that are added to the soil. As a filter, the soil cleans polluted waters that move through it. As a buffer, it resists sudden change in its chemical balance thereby protecting the plants and soil organisms living in it. As a transformer, the soil is able to transform substances through microbiological and biochemical processes. The latter function is vital to the cycling of elements, degradation of toxic substances, decomposition of organic matter and production of greenhouse gases.

c) Habitat and living space. Soil is a habitat for a multitude of flora and fauna which are vital for human life. The largest quantity of organisms on Earth is in the soil. Many of the important antibiotics to treat human diseases are products of soil bacteria. Thus soil management is directly linked to the question of biodiversity. Soil also provides living space for humans and foundation for indrastructure such as roads, buildings, airports and others. Many human illnesses today are caused by soil pollutants that enter the food chain or enter the body through ingestion or inhalation.

d) Cultural heritage. Soil conceals and preserves remnants of past civilizations and plant and animal life. These paleontological and archaeological materials are of great value for the understanding of the history of civilization and the history of Earth.

Soil science is a natural science

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Soil science or pedology (pedo is Greek for ground or soil) is a scientific discipline at the meeting point of physical, biological, geological and agricultural sciences. Because soil is a natural body, soil science is a natural science that deals with the study of soil in all its aspects such as genesis, composition, properties, geography, ecology, fertility, degradation and protection. A more specific definition states that soil science is an environmental (or ecological) natural science concerned with the evolution, characterization, function, distribution, management and protection of the soil resource in terrestrial ecosystems.

What is soil?

2009-05-07T15:09:00.001+08:00

Soil or pedosphere is the thin and fragile skin of the Earth. It is a dynamic natural body that results from the transformation of rocks and sediments by various physical, chemical and biological processes under the influence of climate, topography, organisms and time. Human activities have altered the environment and soil processes in many parts of the Earth that is why man is considered the sixth factor of soil formation.

Soil is the foundation of human civilization. In ancient times, productive soils (i.e. good quality soils) have supported thriving civilizations but soil degradation due to misuse caused the downfall of several of them such as the Mesopotamian and Lydian kingdoms in the Mediterranean region and the Mayan civilization in Central America (Lal, 2006). In recent decades, hunger in certain parts of the world like Africa has been largely caused by unproductive soils. In the Philippines, most of the poorest rural communities are located in degraded lands.

Reference

Lal, R. 2006. Soil science in the era of hydrogen economy and 10 billion people. The Future of Soil Science. IUSS. pp: 76-78.