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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 evalu...

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), "t ropical 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 accur...

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 th...

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) i...

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 (FeSO4.7H2 O) 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...

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 s...

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 f...

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 general...

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 ...

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 fa...

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 km 2 , 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...

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.