Happy World Soil Day

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)

Response of Abaca (Musa textilis Née) to shade, irrigation and fertilization

Abaca plants

Abaca (Musa textilis Née), a relative of the edible banana (Musa acuminata and Musa balbisiana), is a native to the Philippines. It is grown primarily for its fibers which are utilized by the pulp, cordage and fiber craft industries. Studies have shown that the specific tensile strength of abaca fiber is comparable to or even higher than that of fiberglass (Bledzki et al., 2007;Sinon, 2008).

Dr. Marlito Bande and co-workers, in a paper to be published in the international journal Industrial Crops and Products 42:70– 77, reported on the optimum light, nutrient and water requirements of abaca to attain optimum yield. They also discussed how these parameters affect fiber recovery and fiber quality under field conditions. 

They showed that abaca planted under 50% shade had significantly (p < 0.01) higher fiber yield than those planted under the other shade/light treatments (30% and 40% of full sunlight using polypropylene shade nets) since the plants pseudostem under such treatment were longer, bigger and heavier.They revealed that the combination of irrigation and fertilization further enhanced fiber yield to as much as 41% but this was not enough to offset the effects of shade on the performance of the plant which significantly (p < 0.01) increased fiber yield to as much as 165%. Shade and irrigation–fertilizer application had no significant effect on fiber fineness and tensile strength. 

They concluded that 50% shade is the optimum requirement of abaca to achieve an optimum machine stripped fiber yield of 135.04± 4.31 g/plant without affecting fiber quality for industrial purposes.

The study which was conducted in Ormoc, Leyte, Philippines was funded by the German Research Foundation (DFG).

References

Bande MM, J Grenz, VB Asio, and J Sauerborn. 2013. Fiber yield and quality of abaca (Musa textilis var. Laylay) grown under different shade conditions, water and nutrient management. Industrial Crops and Products 42:70–77.

Bledzki AK, AA Mamun, O Faruk. 2007. Abaca fibre reinforced PP composites and expansion with jute and flax fibre PP composites. eXPRESS Polymer Letters 1 (11), 755–762.

Sinon FG. 2008. Optimization of stripping technologies for the production of high quality abaca fiber. Dissertation, Universität Hohenheim, Stuttgart, Germany

Environmental pollution: the case of Xenobiotics

Xenobiotics are chemical substances that are foreign to the biological system. They include naturally occurring compounds, drugs, and environmental agents (Mondofacto online medical dictionary at www.mondofacto.com). The classes of xenobiotics include pesticides, polyaromatic hydrocarbons (PAHs), polychlorinated aromatics, solvents, hydrocarbons, and others (surfactants, silicones, and plastics).

Xenobiotics levels in soils are generally low (less than 100 ppm) unless they are concentrated by application as in the case of pesticides, by spills or by waste disposal. They can occur in soils in solid, dissolved, and gaseous phases and all undergo microbial and abiotic (chemical) transformations (Logan, 2000).

Photo source: www.cleanwaterfund.com

Pesticides are the most important xenobiotic pollutants because of their widespread use in agriculture. In many developing countries, the unregulated use of pesticides by poor farmers contributes not only to environmental pollution but to health problems as well.

In the soil, pesticides can be temporarily fixed through adsorption by soil particles. The persistence or decomposition of pesticides in the soil is influenced by soil moisture, organic matter content, redox potential, soil acidity, soil temperature, texture, adsorption potential, and clay minerals (Schactschabel et al., 1998; Sonon and Schwab, 2004).

References

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

Schactschabel P., H.P. Blume, G. Brümmer, K.H. Hartge and U. Schwertmann. 1998. Lehrbuch der Bodenkunde (14th ed.). Ferdinand Enke Verlag, Stuttgart.

Sonon, L.S. and P.A. Scwab. 2004. Transport and persistence of nitrate, atrazine, and alachlor in large intact soil columns under two levels of moisture contents. Soil Science 169: 541-553.

N.L. Galvez: The Dean of Filipino Soil Scientists

Dr. Nicolas L. Galvez (1903-1991) laid down the groundwork for the different fields of soil science in the Philippines and he trained many Filipino soil scientists as a professor at the University of the Philippines College of Agriculture (UPCA) for 42 years. He was the head of the Soils Department at UPCA from 1948 to 1961, a difficult but crucial post-war period that had a long-term impact on the development of soil science as an academic field in the country. Upon his retirement in 1970, Dr. N.L. Galvez was honored by being appointed as a University of the Philippines Los Banos (UPLB) Emeritus Professor. 

Dr. N.L. Galvez (Source: SAED, UPLB-CA)

Dr. N.L. Galvez was an internationally recognized scientist having published numerous relevant scientific papers on soil chemistry, soil mineralogy, and other aspects of soil science. For his pioneering and great contributions to the development of soil science in the Philippines, Dr. Galvez is widely considered, and deserves to be called, as the “Dean of Filipino Soil Scientists”.

Dr. N.L. Galvez finished his Bachelor of Chemistry at the University of Minnesota, USA, in 1925 and his PhD degree in Soil Science in 1934 from the Institute of Agricultural Chemistry and Soil Science, University of Göttingen, Germany, under the supervision of Prof. E. Blanck (1877-1953), one of the leading soil scientists during the first half of the 20th century who edited the monumental 10-volume Handbuch der Bodenlehre (Handbook of Soil Science) published from 1929 to1932. Dr. Galvez wrote a dissertation entitled “Über Bodenpresssäfte und wurzellösliche Pflanzennärstoffe” (On the pressed soil extract and root-soluble plant nutrients) which was published in the Journal für Landwirtschaft (Journal of Agriculture) Vol. 89, No. 4, pages 257-320 (1934), a prominent peer-reviewed scientific journal at the time.

The University of Göttingen is a world-renowned university associated with such scientific giants as Gauss, Wiechert, Correns, Eigen, Fermi, Debye, Nernst, Langmuir, Heisenberg, Born, Teller, Oppenheimer and many more including nearly 50 Nobel Prize winners. Interestingly, when the great theoretical physicist Werner Heisenberg in Göttingen won the Nobel Physics Prize in 1932, N.L. Galvez was a student there. It is easy to speculate that he must have brushed shoulders with some of the world’s leading scientists (who were teaching or doing research in that small university town of Göttingen) which could have inspired him to excel in his own field of science.  

In recognition of his outstanding scientific achievements, N.L. Galvez was awarded a Guggenheim Fellowship for postdoctoral research at the University of Wisconsin from January 1955 to August 1956 where he worked with M.L. Jackson (1914-2002), one of the most influential American soil scientists and author of the world-famous textbook “Methods of Soil Analysis”.  This postdoctoral experience in Wisconsin which focused on the colloidal minerals of important agricultural soils of the Philippines, must have enhanced further his international standing as a scientist.

In 2008, a museum (N.L. Galvez Hall) was established in his honor at the Soil and Agro-ecosystem Division of the College of Agriculture at UPLB under the able leadership of its former head, Dr. Pearl B. Sanchez, a professor of soil chemistry. It was funded by the US-based family of Dr. Galvez.

(Note: Many of the facts cited were taken from materials available at the above-mentioned N.L. Galvez Hall.)

History of the soil organic matter conversion factor of 1.72

Students of soil science are taught that to determine the amount of soil organic matter, soil organic carbon is measured usually by wet oxidation using potassium dichromate (called Walkley-Black method) or in well-equipped laboratories, using CN analyzer and then multiplied by a conversion factor of 1.72 or 1.724. Most textbooks and laboratory manuals do not explain how this factor was obtained, so students generally accept the value without any question just like they do with other constants used in natural sciences. 

Origin of the conversion factor

The conversion factor has a very long history and has practically survived the test of time and modern analytical methods. It is about 150 years old. It was based on studies in the 1820s by the famous agricultural chemist, Carl Sprengel of Goettingen University, that organic matter contains 58 percent carbon. But it was another leading agricultural chemistry pioneer, Emil Wolff from Hohenheim, who introduced the value of 1.724 in 1864. Since then this conversion factor has become universal despite the many later studies showing that it is too low for most soils and that a value of 2.0 is more accurate (Pribyl, 2010). When I was doing my master thesis at IRRI in the late 1980s, Dr. H.U. Neue, the head of the Soils Department and a leading expert on the organic matter of submerged soils, required us to use a factor of 2.0. 

Oldest records of the conversion factor (Source: Pribyl, 2010) 

In an excellent review of this conversion factor, Pribyl (2010) concluded that convenience, authority, and tradition rather than the strength of evidence are in large part the reason for the widespread acceptance of the conversion factor until now. However, this may be a controversial conclusion for other soil scientists in some countries. In France for instance, analytical laboratories use a factor of 1.72 or 2.0. The former (i.e. 1.72) is better suited for cultivated horizons while the latter (i.e. 2.0) is more appropriate for forest topsoils (Baize, 1988).

Who was Emil Wolff?

Dr. Emil von Wolff (30 Aug 1818-26 Nov 1896) was a professor of chemistry and agricultural chemistry at the Hohenheim Academy of Agriculture and Forestry in Stuttgart, Germany (since 1967 named University of Hohenheim) from 1853 to 1894. Wolff was one of the agricultural chemistry pioneers who made major contributions to its development and to that of soil science, plant science, and animal science. 

Prof. Emil Wolff (Source: Hohenheim Univ)

Emil von Wolff started his studies in medicine at Kiel University in northern Germany but later shifted to natural science which he finished in Berlin. He obtained his PhD in 1843 in Berlin a year after Justus von Liebig published his most important book on agricultural chemistry. This probably influenced him to focus his teaching and research on soil and plant chemistry as well as on the composition of organic substances including foods. He wrote several books among which were the “Textbook of Agricultural Chemistry (1847)” and “Ash Analysis of Agricultural Products (1877). 

Wolff belonged to the most influential and highly regarded agricultural scientists of the 19th century and had no doubt contributed to the fame of the Hohenheim school. It is thus a fitting tribute that an important street at the heart of the Hohenheim University campus bears his name: Emil-Wolff-Strasse (Emil Wolff street).

References
Baize D. 1988. Soil Science Analyses. John Wiley & Sons, Chichester.
Leisewitz, C. 1910.Wolff, Emil von. In: Allgemeine Deutsche Biographie 55 (1910), S. 115-117 [Onlinefassung]; URL: http://www.deutsche-biographie.de/pnd115599533.html?anchor=adb
Pribyl D.W. 2010. A critical review of the conventional SOC to SOM conversion factor. Geoderma 156: 75-83

The geoecology of the limestone and shale areas in Samar, Philippines

Contributed by

Dr. Ian A. Navarrete
Humboldt Fellow
Soil Science of Tropical and Subtropical Ecosystems
Buesgen Institute
University of Göttingen, Germany

Geoecology, a term coined some 41 years ago by the geomorphologist Carl Troll who was at the time professor at the University of Bonn, Germany, is a broad integrative term to the study of forms and functions of terrestrial geoecosystem (Huggett, 1995). It emphasizes the interdependency and/or inter-relationships of the ecological biosphere with landscape and hence sometimes equated with landscape ecology. For example, the movement and distribution of solutes across soil landscapes are influenced by the geomorphic position in the soil within the landscape thus influencing soil genesis (Sommer and Schlichting, 1997) and vegetation development (Huggett, 1975). 

Fig 1. Relation of primary forest and grasslands of Samar

During our fieldwork at the Samar Island Natural Park (along the Paranas-Taft road at about 300 m above sea level) in Feb 2012, we observed two typical grassland ecosystems occurring near or far from the primary forests (Fig 1A).

The first type is the grassland that occurs in the lower residual limestone soil or at the margin of the primary forest. The soils in such grassland are younger as indicated by poor soil profile development. The dominant grass is Paspalum conjugatum which in many areas occur in association with Chromolaena odorata. The second type is the grassland in the degraded rolling and hilly areas usually away from primary forests. The soils in these areas are different from the soils in the primary forest on the upper slopes in that they are mature, reddish, and deep (Fig 1B). They appear to have formed from the limestone residue or from the shale (underlying the limestone) that is widely exposed in the rolling areas. The dominant grass is Imperata cylindrica. 

Fig 2. Primary forest soil in Samar

The soils of the primary forest (limestone forest) on the upper and usually steep slopes are generally very thin and are underlain by consolidated limestone rocks (Fig 2). The presence of nutrient-enriched weathering pockets (where deposition of nutrient and decomposition of organic matter take place) of the limestone parent material, and the high annual rainfall explain the lush growth of the forest vegetation. It also partly explains the high tree species diversity of the forest.

(Members of the team: V.B. Asio, Ariel Bolledo, Mark Moreno, Pearl Carnice, Richel Lupos, Forester Elpidio Cabahit Jr. from the Samar Island Natural Park, and myself)

References

Huggett RJ (1975). Soil landscape systems: a model of soil genesis. Geoderma 13: 1-22.
Huggett RJ (1995). Geoecology: An Evolutionary Approach. Routledge, London.
Sommer M, Schlichting E (1997). Archetypes of catenas in respect to matter-a concept for
structuring and grouping catenas. Geoderma 76:1-33.

Ethnopedology: the study of local soil knowledge

“There is a need to integrate science and local knowledge. Both are vital and can be brought together only by participation” emphasized Prof. Dr. Franz Heidhues in his concluding remarks during the International Scientific Conference on Sustainable Land Use and Rural Development in Mountain Areas held at the University of Hohenheim, Germany on 16-18 April 2012. As can be seen from the figure below, scientific knowledge becomes more relevant when it is combined with local knowledge (Barrios and Trejo, 2003).

Precision & relevance of scientific and local knowledge  

Ethnopedology is the study of the local knowledge on soil and land systems of rural populations, from the most traditional to the modern. Ethnopedological research covers a wide diversity of topics centered around four main issues: (1) the formalization of local soil and land knowledge into classification schemes; (2) the comparison of local and technical soil classifications; (3) the analysis of local land evaluation systems; and (4) the assessment of agro-ecological management practices (Barrera-Bassols and Zinck, 2003; Barrios and Trejo, 2003). It encompasses many aspects, including indigenous perceptions and explanations of soil properties and soil processes, soil classifications, soil management, and knowledge of soil–plant interrelationships (Talawar, 1996).

In a recent study conducted in Vietnam and Thailand and presented in the above-mentioned scientific conference in Hohenheim, Dr. Gerhard Clemens and co-workers found, among other things, that: 1) Farmers classify their soils first of all according to soil color; 2) Farmers are able to describe soil properties and features. They also know the local factors affecting their soil; 3) Local soil classification is not consistent but the predominant soils can be efficiently identified using local soil knowledge.

An old farmer sharing some traditional knowledge 

Our own research in the degraded lands of Parasanon, Pinabacdao, Samar showed that the sweetpotato farmers possess a local knowledge system with regards to the nature of the soil and that of their sweetpotato crop. The demographic traits of the farmers clearly differed but they adhered to the same knowledge system regarding the attributes of the soil in their locality and the growth condition of their sweetpotato plants. Using their native dialect, the farmers have a soil classification scheme based on textural characteristics; they have also certain indicators of soil fertility and plant health. Moreover, the farmers know of certain problems concerning their soil or crop but they are not detracted by these because of their experience in finding ways to circumvent the situation (Pardales et al., 2001).

There has been an increasing research interest in local soil knowledge in recent years. This is the result of a greater recognition that the knowledge of people who have been interacting with their soils for a long time can offer many insights about the sustainable management of tropical soils (Barrios and Trejo, 2003).

References

Barrios E and MT Trejo. 2003. Geoderma 111: 217-231
Barrera-Bassols N and JA Zinck 2003. Geoderma 111: 171-195
Clemens G, U Schuler, BL Vinh, H Hagel, and K Stahr. 2012. International Scientific Conference on Sustainable land use and Rural Development in Mountainous Areas, University of Hohenheim, Stuttgart, 16-18 April 2012
Heidhues F. 2012. Conclusions. International Scientific Conference on Sustainable land use and Rural Development in Mountainous Areas, University of Hohenheim, Stuttgart, 16-18 April 2012.
Pardales JR, VB Asio, AB Tulin and DM Campilan. 2001. Project Report, UPWARD-CIP, Laguna.
Talawar, S., 1996. Research paper #2.Department of Anthropology, University of Georgia, Athens, USA.

Masaryk University and geology in the beautiful historic city of Brno (Czech Republic)

Brno's city center

If you have the chance to travel to the Czech Republic, you should not forget to include in your itinerary a visit to the city of Brno, the second largest city in the Czech Republic. Located south of Prague (about 2 hours by train), Brno is the historical capital city of Moravia of the South Moravian Region, one of 14 regions of the country.

Brno is among the most beautiful European cities that I have visited. According to Wikipedia, the city has hundreds of historical sights, including one designated a World Heritage Site by UNESCO, and the second largest historic preservation zone in the Czech Republic next to Prague. It is a university city and boasts of several top universities (total student population of about 90,000) one of which is Masaryk University.

Masaryk University

Masaryk University, named in honor of Tomáš Garrigue Masaryk the first president of Czechoslovakia, is the second-largest public university in the Czech Republic and the leading university in Moravia. It has more than 190 departments, institutes and clinics organized into nine faculties. It is commonly regarded as one of the most significant institutions for education and research in the Czech Republic and a respected Central European university. The university is home to RECETOX (Research Center for Toxic Compounds in the Environment), an excellent environmental research center which is highly regarded in Europe.

The city is not only beautiful, it is clean and orderly. The people are of course generally friendly and willing to assist visitors. A walk around the historical city center led me to the impressive St Peter and Paul Cathedral on top of Petrov hill. The hill is built up by metamorphic rocks particularly schist.

Outside the city I have observed limestones, sandstones, and metamorphic (quartzite, schist) outcrops. Most of the soils around Brno appear to be Cambisols, Chernozems, and probably Luvisols in the World Reference Base (WRB) classification system.  

Characteristics and fertility constraints of degraded soils in Leyte, Philippines

Contributed by

Dr. Ian A. Navarrete

Humboldt Fellow

Soil Science of Tropical and Subtropical Ecosystems

Georg-August Univesity Göttingen

Gottingen, Germany

Soil degradation, a process that lowers the capacity of the soil to produce goods or services, is a prevalent agricultural and environmental problem in the Philippines (Asio et al. 2009). However, to date, the nature and characteristics of degraded soils in the Philippines have been poorly understood, in that there have been few studies on this subject (Asio et al. 2009; Navarrete et al. 2009). Although various crop production technologies have been developed for marginal areas these technologies have not been successfully adapted by farmers or have failed to alleviate crop production (Cramb 2001). Cramb further stated that the introduction of unsuitable soil management technologies to farmers has intensified the soil degradation processes occurring in these areas. Thus, knowledge on the characteristics and fertility status of degraded soil is fundamental in planning suitable soil management strategies for crop production purposes. Because the degree of soil degradation immensely varies among sites depending on soil forming factors, soil management strategies must be location specific, every degraded soil has to be evaluated in terms of its properties and constraints.

In our recent study published in the international journal Archives of Agronomy and Soil Science (Navarrete et al. 2012), 60 soil horizon samples were collected from five locations (across an elevation gradient between 97 and 735 m above sea level) at Ormoc, Baybay, Bontoc, Bato and Matalom on the western side of Leyte island, Philippines. The samples were subjected to various physical, chemical and mineralogical analysis. Results revealed that the most important physical constraint in most of the soils evaluated is the high clay content particularly in the soils of Baybay and Bato because it is a problem for cultivation. The strongly acidic and strongly alkaline pH, low available P and, in some cases, low exchangeable K are the chemical constraints. Most of the variations in the physical and chemical constraint of these degraded soils can be explained directly or indirectly by the nature of the parent material, geomorphic position and anthropogenic effect. Soil fertility characteristics are distinct within similar soil types, primarily because they are related to the dominant soil-forming processes (see for example Figure 1 below). Consideration of the soil physical and chemical constraints is essential for the long-term planning of soil management strategies that will lead to sustainable utilization of these problematic soils.

Figure 1. Plots of the first and second principal components (PC) extracted from the principal component analysis (PCA) of all selected properties. (a) distribution of soil samples and soil types (b) distribution of soil properties

References

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

Cramb RA (ed). 2001. Soil conservation technologies for smallholder farming systems in the Philippine uplands: a socioeconomic evaluation, ACIAR, Australia.

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

Navarrete IA, Tsutsuki K, Asio VB. 2012. Characteristics and fertility constraints of degraded soils in Leyte, Philippines. Archives of Agronomy and Soil Science. DOI /10.1080/03650340.2012.663908

How does mining affect the environment?

The major impact of mining on the environment is mainly due to the physical damage of the landscape and the production of a large volume of harmful wastes. In general, only a small fraction of the ore is valuable, the remaining large part is waste (tailings). For example, in the Cu mining industry, only about a kilogram of the metal is extracted from one-half ton rock. (Ore is an economic term for a rock from which a mineral can be extracted profitably).

The figure above summarizes the environmental impact of mining and smelting. It shows that mining and smelting produce solid, liquid, and gaseous wastes/contaminants. These cause serious environmental damage once they are discharged to the land (terrestrial ecosystem) and bodies of water (aquatic ecosystems) or when they are emitted into the ambient air. In particular, they cause soil and water acidification, air, water, soil and plant contamination by trace elements, deterioration of soil biology and fertility, and soil erosion.

Studies have shown that trace metals remain in the soil for a long time ranging from hundreds to thousands of years. Cd, Ni, and Zn have a relatively shorter residence time in the soil than Pb and Cr which may remain for several thousand years. This simply means that it is not easy and cheap to rehabilitate an abandoned mining site. In fact, the physical destruction of the landscape can be irreparable. And more importantly, the health risk of the contaminants that have already entered the food chain can remain for a long time.

Photo: Manicani island, Eastern Samar. Source: www.nickelore.blogspot.com (Feb 2, 2012)

References

Skinner B.J., S.C. Porter, and J. Park. 2004. Dynamic Earth. An introduction to Physical Geology. John Wiley and Sons, NJ.

Dudka S. And D.C. Adriano. 1997. Environmental impacts of metal ore mining and processing: a review. Journal of Envi. Quality 26: 590-602.

Melanterite Soil: A green soil in the highlands of Samar

A soil at the heart of Samar, the third largest island of the Philippine archipelago, and along the Paranas-Taft road at about 300 m above sea level (within the Samar Island Natural Park) easily catches the attention of travellers. This is because it is unique: it is green in color. As far as I know, no soil with such color has yet been reported in the scientific literature.

The melanterite soil near the Bagacay mining area in Samar island

The dominant green color is probably due to the abundance of the secondary mineral called melanterite, a hydrated iron sulphate mineral (FeSO4.7H2O) formed from the decomposition of pyrite or other iron minerals due to the action of surface waters. Melanterite is known to be stable only under highly acidic condition. It is commonly found in mines as a post-mining formation on mine walls, in sulfidic sedimentary and metamorphic rocks as well as in coal and lignite deposits. It indicates the possible presence of sulfuric acid and should not be handled with bare hands or inhaled (www.mindat.org).

Photo of the site along the highway in Central Samar where the melanterite soil occurs

The green soil we have examined in Samar developed from mudstone interlayered with coal deposit. The site is not far from an area which was mined for coal and pyrite and thus it appears to satisfy the environmental conditions favorable for melanterite occurrence.

We had the chance to examine the soil during our fieldwork in Samar on 2-3 Feb 2012 as part of my graduate course in pedology (Soil Science 212). We plan to conduct a detailed pedological and geochemical study on this soil in the near future. For easy reference, I suggest to call it “Samar melanterite soil”.

Recent updates: In the book "Assessment, Restoration and Reclamation of Mining Influenced Soils" edited by Prof. Jaume Bech (University of Barcelona) and his colleagues and published by Academic Press, London, in 2017,  the occurrence of melanterite mineral in some mining-affected soils from Spain and Portugal has been mentioned. This seems to confirm our observation about the green soil in Samar in 2012.

(Members of the team: Ariel Bolledo, Mark Moreno, Pearl Carnice, Richel Lupos, Dr. Ian Navarrete (Humboldt Research Fellow), Forester Elpidio Cabahit Jr. from the Samar Island Natural Park, and myself (VBA)).

The origin of the catena concept

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 a 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. He and his students have shown that the downward transport of solids or solutions may lead to a direct or indirect linkage between catena elements (Sommer and Schlichting, 1997; see above figure). In Schlichting’s view, the genesis of soil can only be understood if its relation to the other soils in the catena is taken into consideration.

Typical catena in the volcanic areas of Leyte, Philippines

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