What is soil analysis?

President Rodrigo R. Duterte emphasized the conduct of soil analysis in the country during his first State of the Nation Address (SONA) on July 15, 2016. He said that “we shall also conduct a nationwide soil analysis to determine areas most suitable for rice farming to optimize production with the use of effective soil rehabilitation and fertilization.”

As an effect of this presidential pronouncement, many people including professionals from various academic fields have been wondering what soil analysis is. Several readers of this blog suggested that I write about this topic hence, this article.

Soil analysis refers to the measurement of soil physical, chemical, and biological properties. It is done, depending on the type of soil analysis, for the following purposes: 1) to evaluate the origin and formation of the soil; 2) to assess the level of contamination of the soil; 3) to characterize the soil as a habitat of soil organisms; 4) to assess the soil fertility status, and 5) to evaluate the soil’s suitability for certain crops. Soil analysis is generally synonymous with soil testing. The major steps of soil analysis are soil sampling (and field soil examination) and laboratory analysis.

Soil profile examination and sampling to evaluate the origin of the soil

The first type of soil analysis is the most difficult and complex type. It is carried out by soil specialists called pedologists.  It involves detailed field description of the soil using standard procedures such as the Guidelines for Soil Description (4th edition by Jahn et al., 2006) published by FAO, Rome. Soil description is done on newly dug soil pit at least 1.5m deep or fresh road cuts. The collection of soil samples for intensive laboratory analysis is done on every soil layer (soil horizon) down to the bedrock. Laboratory analyses include the physical, chemical, and mineralogical properties of the soil. Geochemical analysis of rock samples is also necessary.

The second type is conducted by soil scientists interested in soil pollution or contamination. Soil samples are usually collected in areas where soil contamination is suspected. Soil sampling is done at random or at fixed intervals. Only the topsoil layer (0-10 or 0-20 cm) is sampled using a soil auger or a similar sampling tool. Soil samples are analyzed for their contents of soil pollutants (e.g. heavy metals) and are compared with published threshold values to know if the sample is contaminated or not.

Soil sampling to assess the contamination of Taft River in E. Samar

The third type of soil analysis is conducted to know if the soil is favorable for certain soil organisms of interest (e.g. earthworms). This is popular among soil ecologists. Soil samples are collected usually from the topsoil layer and then they are analyzed for soil physical and chemical properties. Correlation analysis is then done between the population of the soil organism and the different soil properties to know which among the soil properties influences the population of the organisms.

The fourth type is the most well-known and commonly done type of soil analysis to support crop production. The main purpose is to know if the soil is fertile or not. Specifically, it is performed to assess, using high-tech laboratory equipment,  if the soil contains sufficient amounts of the essential nutrients required by plants (crops) to grow well and produce good yield (grain, tubers). The essential nutrients that the plant takes up from the soil include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), boron (B), chlorine (Cl) and nickel (Ni). Since N, P, and K are required by the plant in the largest amounts, these three are usually the nutrients that are of limited supply in the soil. So farmers need to know how much of these nutrients must be applied to the soil through fertilizers. The final result of this type of soil analysis is a fertilizer recommendation.

Soil sampling for fertility evaluation

The fifth and last type of soil analysis is carried out to assess if a certain soil is suitable for crops such as rice, corn, vegetables, fruit trees, and others. This involves field soil examination to know the soil’s texture, structure, drainage, slope, and depth using the methods of the first type of soil analysis. The soil samples are analyzed for soil chemical properties such as soil pH, organic matter content, nutrient holding capacity as well as the amounts of the major nutrients (similar to the third type of soil analysis). The soil properties are then matched with the ecological requirement of the crop. The final result is a suitability map or table showing suitable crops for each soil. It also indicates the soil constraints (or problems) if a crop is grown in soil that is not suitable for that particular crop.

From the president’s pronouncement, it looks like that he meant the fifth type of soil analysis. Due to the tremendous amount of field and laboratory works, it cannot be done by the Bureau of Soil and Water Management alone. It needs the participation of universities with strong soil science program throughout the country such as Central Luzon State University, University of the Philippines Los Banos, Visayas State University, Central Mindanao State University, and University of Southern Mindanao.

Soil science students at VSU performing laboratory analysis of soil samples

The laboratory step of soil analysis or soil testing is tedious, time-consuming, and costly because the chemicals and apparatus required are very expensive. Although there are some rapid soil test kits available, they are not reliable. Also, the laboratory analysis has to be done according to accepted procedures and by trained personnel. Examples of accepted procedures of laboratory analysis of soils are:

Carter M.R. and E.G. Gregorich (Eds.). 2008. Soil Sampling and Methods of Analysis (2nd ed). CRC Press, Boca Raton.

International Soil Reference and Information Center (ISRIC). 1995. Procedures for Soil Analysis (L.P. Van Reuwijk, Editor). Wageningen, the Netherlands.

Jones J. B. Jr. 2001. Laboratory Guide for Conducting Soil Tests and Plant Analysis. CRC Press, Boca Raton.

Margesin R. and F. Schinner(Eds.). 2005. Manual for Soil Analysis – Monitoring and Assessing Soil Bioremediation. Springer Verlag, Berlin.

Pansu M. and J. Gautheyrou. 2006. Handbook  of Soil Analysis. Mineralogical, Organic  and Inorganic Methods. Springer Verlag, Berlin.

Schlichting E., H.P. Blume and K. Stahr. 1996. Bodenkundliches Praktikum (Soil Science Practicum). Blackwell Wissenschaftsverlag, Berlin.

Sparks D.L., A.L. Page, P.A. Helmke and R.H. Loeppert (Eds.). 1996. Methods of Soil Analysis Part 3—Chemical Methods. Soil Science Society of America, Madison, Wisconsin.

Westerman R.L. (Ed.). 1990. Soil Testing and Plant Analysis (3rd ed). Soil Science Society of America, Madison, Wisconsin.

Tropical soils: some important aspects of these less understood soils

Tropical regions occur between the Tropic of Cancer and the Tropic of Capricorn. The tropics include approximately 40% of the land surface and is the largest ecozone of the earth. According to Köppen (1931), the tropics are characterized by an annual mean air temperature above 18°C through­out the whole year. The largest climatic variation is introduced by the variability of precipita­tion, reaching from nearly 0 mm in the Saharan and Atacama Desert to 11,700 mm on Mt. Waialeala in Hawaii (Eswaran et al., 1992).

An Afisol (Luvisol) soil derived from mudstone in Eastern Samar, Philippines

According to Uehara and Gillman  (1981), "tropical soils" is a common name used to identify any soil that occurs in the tropics. They noted that like most common names, the term lacks precision, but it is more readily understood by a larger audience than are the scientific names. In contrast, Sanchez (1976) argued against the use of the term "tropical soils" since it does not accurately reflect the soils in the tropics. 

Selected properties of the major tropical soils (Jahn and Asio, 2006)

The name tropical soils is now globally accepted but these soils have remained poorly understood until now. The following are some important aspects of tropical soils (Jahn and Asio , 2006):

1. The tropics,  the world’s largest ecological zone, have a very high potential for plant growth but with soil limitations in vast areas.
2. About one-third of the soils of the world are tropical soils. The most widespread are Ferralsols, Acrisols, Luvisols, Cambisols, and Arenosols.

3. The large proportion of Cambisols (Inceptisols) and Luvisols (Alfisols) in Southeast Asia re­flects clearly the younger age of land surfaces and therefore the short duration of weathering processes.

4. Some soils occur almost exclu­sively within the tropics. About 90% of the Ferralsols (Oxisols), 80% of the Nitisols (Oxisols/Ultisols), and 60% of the Acrisols (Ultisols) are situated in tropical regions.
5. The major soil limitations or soil constraints  are  low cation exchange capacity, low base saturation (low pH, high Al-saturation) and high P retention. They are most widespread in South America, Africa and Southeast Asia (in decreasing order based on area).
6. Physical constraints like high groundwater table, air deficiency, and low soil depth are of lesser significance but govern special requirements for soil management in specific landscapes.
7. Due to severe chemical limitations, proper management of nutrients is the main challenge for effective land-use systems in the tropics.
8. Internal and external fluxes of nutrients are different among soil types and different among tropical landscapes. These have to be considered in ecological land-use systems.
9. To conserve the stock of organic matter in tropical soils (and to increase it in degraded soils), biomass productivity will be a key point for ecological land-use systems.
10. To enable policy-makers as well as land users to establish sustainable and ecological land use systems in the tropics, more precise soil maps and soil information are needed.

References

Eswaran H., J. Kimble, T. Cook & F.H. Beinroth. 1992. Soil diversity in the tropics: Implications for agricultural development. In: Myths and Science of Soils in the Tropics. SSSA Special Publ. No. 29.

Jahn R. and V.B. Asio. 2006. Climate, geology and soils of the tropics with special reference to Southeast Asia and Leyte (Philippines). In: Proc. 11th International Seminar-Workshop on Tropical Ecology, 21-25 Aug 2006, VSU, Baybay City, Leyte, pp: 23-42.

Köppen W. 1931. Grundriss der Klimakunde. W. de Gruyter & Co., Berlin

Sanchez, P.A. 1976. Properties and Management of Soils in the Tropics. Wiley, New York

Uehara G. and G. Gillman. 1981. The Mineralogy, Chemistry, and Physics of Tropical Soils with Variable Charge Clays. Westview  Press, Boulder Colorado.

Highly weathered soils from Visayas, Philippines

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

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.

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)).

Biocalcification: the biological accumulation of CaCO3 in rice soils

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.

Relation between properties and age of soils in the Amazon forest

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

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 fieldwork 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 management practices there. Puddling is the process of destroying the structure of rice soil by cultivating it when it is wet in order 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 widespread. The group examined a 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 a 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).

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

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.

Are the tropical soils in Southeast Asia unique?

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.

Effects of warfare on soil development

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

Soil science is a natural science

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.