|Photo source: www.museumplatkow.de|
Saturday, August 17, 2013
In 1979, Bernhard Ulrich was the first researcher to discover the connection between air pollution and the forest decline or dieback (Waldsterben) in Germany. He hypothesized that acid rain results in soil acidification which in turn causes the forest dieback phenomenon. According to his soil acidification hypothesis, as soil becomes more acidic there is a release of aluminum that damages the roots of the trees. This leads to the following effects: reduction in uptake and transport of some cations, reduction in root respiration, damage to fine feeder roots and root morphology, and reduction in elasticity of the cell walls. The discovery was first published by Ulrich and co-workers in "Deposition von Luftverunreinigungen und ihre Auswirkungen in Waldökosystemen im Solling." Schriften Forstl. Fak. Univ. Goettigen 58, Sauerländer Verlag, Frankfurt a.M., 291pp.
1. Rocks contain only bases and no acid precursors. Therefore, with the exception of sulfide containing rocks, soils cannot acidify as a result of atmospheric rock weathering.
2. A consumption of protons in rocks and soils results in a decrease of their acid neutralizing capacity and can result in the buildup of a base neutralizing capacity.
3. Weak acids (carbonic acid) lead in geological times to the depletion of bases without a larger accumulation of labile cation acids. Strong acids (HNO3, organic acids, H2SO4) can lead within a few decades to soil acidification.
4. The acid input caused by the natural emission of SO2 and NOx can be buffered by silicate weathering even in soils low in silicates.
5. The cause of soil impoverishment and soil acidification is a decoupling of the ion cycle in the ecosystem.
6. Acid deposition in forest ecosystems which persists over decades leads to acidification.
7. Formation and deposition of strong acids with conservative anions (SO4, NO3) shifts soil chemistry into the Al or Al/Fe buffer range up to a great soil depth.
8. In the long run, soil acidification by acid deposition results in the retraction of the root system of acid tolerant tree species from the mineral soil, and in water acidification.
Bernhard Ulrich was professor of forest soil science and forest nutrition at the University of Goettingen, Germany, from 1965 until his retirement in 1991. He obtained his PhD in agricultural science from the University of Hohenheim, Stuttgart, in 1953 based on a dissertation on the rapid determination of soil cation sorption capacity. He was widely recognized as the leading expert of soil acidification and forest ecosystem research.
Sunday, August 11, 2013
Weathering is the alteration by chemical, mechanical, and biological processes of rocks and minerals at or near the Earth’s surface, in response to environmental conditions.
Highly weathered soils (or strongly weathered soils) are soils that have undergone prolonged and intense weathering under the net leaching environment of the humid tropics. They are commonly found on stable and old geomorphic surfaces underlain by easily weatherable rocks such as ultrabasic and basic rocks as well as by pre-weathered sediments (Beinroth, 1982). These soils are clayey, deep, reddish, acidic, and have low nutrient status. According to Jackson et al. (1948), highly weathered soils are characterized by weathering stages of 10 to 12 wherein the clay fraction is dominated by 1:1 phyllosilicates (kaolinite & halloysite), aluminum oxide (gibbsite), and iron oxides (goethite and hematite). This mineralogical characteristic is also predicted by the “residua hypothesis” of Chesworth (1973) which states that soil composition will with time move towards the residua system composed of SiO2, Al2O3, Fe2O3, and H2O. In the USDA Soil Taxonomy, the highly weathered soils belong to the Ultisols and Oxisols orders. In the World Reference Base, these soils belong to the reference soil groups Alisols, Acrisols and Ferralsols. These soils possess nutritional problems for crop growth and thus are a problem for agriculture.
(Beinroth, F.H. 1982.Geoderma 27(1982)-1-73; Chesworth, W. 1973. J. Soil Science 24: 69-81; Jackson, M.L. et al. 1948. J. Physical and Colloidal Chemistry 52: 1237-1260).
Below are photos of the important highly weathered soils from Leyte, Negros and Samar islands in the Visayas.
|This is an Oxisol that formed from ultrabasic rock in Salcedo, Eastern Samar|
|The widespread red soil (Ultisol) in the volcanic area of Central Negros|
|An Ultisol on pre-weathered sediments from basalt in Silago, Southern Leyte|
|An Ultisol formed on pre-weathered sediments from basalt in Biliran, Leyte|
The widespread soil from basalt on the lower slopes of Mt. Pangasugan, Baybay, Leyte
Thursday, June 20, 2013
The latest issue of the International Union of Soil Sciences (IUSS) bulletin is now available. The bulletin, the official publication of IUSS (formerly International Society of Soil Science or ISSS) with approximately 60,000 members worldwide, has a long and distinguished history. The first volume was produced by F.A.van Baren and published in 1952. The society president at the time was the renowned soil scientist, Prof. R. Tavernier from Gent, Belgium.
In the Introduction of the maiden issue, Prof. Tavernier wrote that “the bulletin of the International Society of Soil Science aims to pass on official information about all important events concerning the life and activity of the Society to its members and to National Societies and Regional Groupings as well as to Research Institutes. We hope that this bulletin will satisfy our members’ wishes, who have expressly shown their desire to be informed about these activities and about the development of Soil Science in the diverse countries of the world. We also hope that it will serve to reinforce the already excellent relations between our members, and to stimulate international scientific cooperation.”
|IUSS Bulletin 122 (June 2013)|
The above photo shows the soil scientists from VSU during a pedological field work in the volcanic central highlands of Leyte, Philippines (740m asl) in early 2012.
Monday, May 13, 2013
Arsenic (As) is a heavy metal that is well-known as a poison and a carcinogen. Its average concentration in the soil ranges from 5 to 6 mg/kg which is generally related to rock type and industrial activity.
Arsenic contamination of paddy soils is widespread and elevated arsenic levels in rice grains is now a hot issue in many parts of the world. Martha Rose Shulman wrote in the New York Times (15 April 2013) that “it is clear that the levels of inorganic arsenic in rice and rice products are high, and that we and especially children, babies and pregnant women should limit our intake of rice and rice products.”
According to Bogdan and Schenk (2012) in their recent study published in the highly respected Journal of Plant Nutrition and Soil Science (Wiley-VCH Verlag GmbH), flooded rice may contain high arsenic concentration compared to other grain crops. In fact, aside from arsenic-contaminated drinking water, rice is the largest food dietary source of inorganic arsenic. This is because the reducing environment in flooded rice fields causes the dissolution of arsenic and thus increases its availability to the rice plant. Meharg (2004) added that under paddy field conditions, inorganic arsenic introduced into the soil is inter-converted between the reduced inorganic species arsenite (the dominant type) and the oxidized species arsenate. Moreover, arsenite is taken up into the root by the highly efficient Si pathway and arsenate can be taken up via the phosphate transport system.
Bogdan and Schenk (2012) observed among other things that continuous arsenic supply in the soil resulted in doubling of arsenic concentration in rice shoot and grains. They also found that arsenic was mobilized from the root and shoot to the rice grains where it accumulated.
Bogdan K. and M.K. Schenk. 2012. Arsenic mobilization in rice (Oryza sativa) and its accumulation in the grains. J. Plant Nutr. Soil Sci. 175: 135-141.
Meharg A.A. 2004. Arsenic in rice-understanding a new disaster for Aouth-East Asia. Trends in Plant Science 9: 415-417.
Tuesday, April 16, 2013
The Visayas State University (VSU), through the Philippine Higher Education Research Network (PHERNet) of the Commission on Higher Education (CHED), is spearheading a research project on enhancing farm productivity and environmental quality in climate change vulnerable marginal uplands in Eastern Visayas. As part of the project activities, the university will organize a National Conference on Development Initiatives in the Philippine Philippine Marginal Uplands, with the theme, "Enhancing farm productivity and environmental quality of Philippine marginal uplands: A scan of the past and a look into the future." The conference will be held on 22-24 October 2013 at VSU, Baybay City, Leyte.
Wednesday, March 6, 2013
Marginal uplands are hilly or mountainous lands having very low crop productivity due to poor soil quality (degraded soil), limited water availability, and unfavorable socio-economic conditions. They are widespread in Southeast Asia and other parts of the humid tropics (e.g., Agustin and Garrity 1995; Asio et al., 2009). Resource poor-farmers (~ 1.4 billion people) in the developing world are located on these risk-prone marginal environments (Altieri 2002).
|Marginal uplands in Inopacan and Hindang, Leyte|
In the Philippines, the poorest households, who are also the most vulnerable and most food insecure, are living and farming on these marginal lands (Roa 2007). The agro-ecological conditions in these areas are typically not suited to intensive production systems due to low-quality soils, hilly slopes, limited access to inputs or markets and extremely diverse and site specific conditions (Asio et al., 2009; Tyler 2004). Crops that can be grown on these marginal lands are often restricted to root crops such as sweet potatoes, beans and other legumes, thereby limiting food supply and diversity in hilly lands. In addition, farmers often seek seasonal off-farm employment to survive. Thus, research efforts are urgently needed to enhance food security and alleviate the difficult and risk-prone living conditions of these poor farming households.
|A daughter of a poor farmer living in the marginal upland of Inopacan, Leyte|
Two on-going research projects on marginal uplands at VSU are the CHED-funded Philippine Higher Education Research Network (PHERNET) Program on “Enhancing food production and environmental quality in climate change vulnerable marginal uplands of Eastern Visayas” and the NRCP-funded project “Characteristics and nutrient status of degraded upland soils in Samar Island”.
|Poor soil quality and low biodiversity characterize marginal uplands|
Agustin PC and Garrity DP (1995). Historical land use evolution in a tropical acid upland agroecosystem. Agriculture, Ecosystems and Environment 53:83-95.
Altieri MA (2002). Agroecological principles for sustainable agriculture. In: Agroecological Innovations (N. Uphoff, ed.). Earthscan, London, pp: 40-46.
Asio VB, Jahn R, Perez FO, Navarette IA, and Abit SM Jr (2009). A review of soil degradation in the Philippines. Annals Tropical Research, 31:61-94.
Roa JR (2007). Food security in fragile lands. PhD Dissertation, Wageningen University, Netherlands.
Tyler S (2004). Participatory research for community-based natural resource management in Asia. JIRCAS International Symposium Series 12: 165-169.
Wednesday, December 5, 2012
The Department of Agronomy and Soil Science at Visayas State University in Leyte, Philippines joins the global community of more than 60,000 soil scientists in celebrating the World Soil Day today, December 5.
Our soil science program at VSU is now more than 30 years old. It produced the first batch of BSA (Soil Science) graduates in 1980. It is now among the top soil science programs in the Philippines.
Many of our BS alumni have become very successful professionals/scientists in various academic and research institutions in the Philippines and other parts of the world.
We are very proud to name a few:
Dr. Leticia S. Sonon, University of Georgia, USA
Dr. Marife D. Corre, University of Goettingen, Germany
Dr. Nilda R. Burgos, University of Arkansas, USA
Dr. Sergio M. Abit Jr., Oklahoma State University, USA
Dr. Joel Bandibas, National Institute of Advanced Industrial Science & Technology (AIST), Japan
Dr. Constancio Asis, Jr., Philippine Rice Research Institute (Philrice)
Dr. Ian A. Navarrete, University of Goettingen, Germany
Mr. Marco Rodel J. Aragon, Del Monte Philippines (First Placer, 2007 Board Exam for Agriculture)