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Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and Soil survey; Soil physics, Soil chemistry, Soil biology, and fertility properties of soils; and these properties in relation to the use and Soil management.Jackson, J. A. (1997). Glossary of Geology (4. ed.). Alexandria, Virginia: American Geological Institute. p 604.
The main branches of soil science are pedology ― the study of formation, chemistry, morphology, and classification of soil ― and edaphology ― the study of how soils interact with living things, especially plants. Sometimes terms which refer to those branches are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned. Indeed, engineers, agronomy, , , physical geographers, ecologists, , , forestry, public health, Archaeology, and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences.
Soil scientists have raised concerns about how to preserve soil and arable land in a world with a growing population, possible future Water scarcity, increasing per capita food consumption, and land degradation.
WRB is based mainly on soil morphology as an expression of pedogenesis. A major difference with USDA soil taxonomy is that soil climate is not part of the system, except insofar as climate influences soil profile characteristics.
Many other classification schemes exist, including vernacular systems. The structure in vernacular systems is either nominal (giving unique names to soils or landscapes) or descriptive (naming soils by their characteristics such as red, hot, fat, or sandy). Soils are distinguished by obvious characteristics, such as physical appearance (e.g., Soil color, Soil texture, landscape position), performance (e.g., production capability, flooding), and accompanying vegetation. A vernacular distinction familiar to many is classifying texture as heavy or light. Light soil content and better structure take less effort to turn and cultivate. Light soils do not necessarily weigh less than heavy soils on an air dry basis, nor do they have more porosity.
Contemporaries Friedrich Albert Fallou (the German founder of modern soil science) and Vasily Dokuchaev (the Russian founder of modern soil science) are both credited with being among the first to identify soil as a resource whose distinctness and complexity deserved to be separated conceptually from geology and crop production and treated as a whole. As a founding father of soil science, Fallou has primacy in time. Fallou was working on the origins of soil before Dokuchaev was born; however Dokuchaev's work was more extensive and is considered to be the more significant to modern soil theory than Fallou's.
Previously, soil had been considered a product of chemical transformations of rocks, a dead substrate from which plants derive nutritious elements. Soil and bedrock were in fact equated. Dokuchaev considers the soil as a natural body having its own genesis and its own history of development, a body with complex and multiform processes taking place within it. The soil is considered as different from bedrock. The latter becomes soil under the influence of a series of soil-formation factors (climate, vegetation, country, relief and age). According to him, soil should be called the "daily" or outward horizons of rocks regardless of the type; they are changed naturally by the common effect of water, air and various kinds of living and dead organisms.Krasilnikov, N.A. (1958) Soil Microorganisms and Higher Plants
A 1914 encyclopedic definition: "the different forms of earth on the surface of the rocks, formed by the breaking down or weathering of rocks". serves to illustrate the historic view of soil which persisted from the 19th century. Dokuchaev's late 19th century soil concept developed in the 20th century to one of soil as earthy material that has been altered by living processes.. A corollary concept is that soil without a living component is simply a part of Earth's outer layer.
Further refinement of the soil concept is occurring in view of an appreciation of energy transport and transformation within soil. The term is popularly applied to the lunar soil and Mars, a usage acceptable within a portion of the scientific community. Accurate to this modern understanding of soil is Nikiforoff's 1959 definition of soil as the "excited skin of the sub aerial part of the Earth's crust".
One exciting effort drawing in soil scientists in the U.S. is the Soil Quality Initiative. Central to the Soil Quality Initiative is developing indices of soil health and then monitoring them in a way that gives us long-term (decade-to-decade) feedback on our performance as stewards of the planet. The effort includes understanding the functions of soil microbiotic crusts and exploring the potential to sequester atmospheric carbon in soil organic matter. Relating the concept of agriculture to soil quality, however, has not been without its share of controversy and criticism, including critiques by Nobel Laureate Norman Borlaug and World Food Prize Winner Pedro Sanchez.
A more traditional role for soil scientists has been to map soils. Almost every area in the United States now has a published soil survey, including interpretive tables on how soil properties support or limit activities and uses. An internationally accepted soil taxonomy allows uniform communication of soil characteristics and soil functions. National and international soil survey efforts have given the profession unique insights into landscape-scale functions. The landscape functions that soil scientists are called upon to address in the field seem to fall roughly into six areas:
There are also practical applications of soil science that might not be apparent from looking at a published soil survey.
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