Soil Science

What is Soil?

Soil is the naturally occurring, unconsolidated or loose covering of broken rock particles and decaying organic matter on the surface of the Earth, capable of supporting life.

Soil particles pack loosely, forming a soil structure filled with pore space. This porosity holds ever changing reciprocal amounts of soil solution (liquid) and air (gas). Accordingly, soils are often treated as a three state system.

Soil is also known as earth: it is the substance from which our planet takes its name.

Soil forms by the combined action of physical, chemical, biological, and anthropogenic processes on soil parent material resulting in differential alteration causing the formation of distinct soil horizons.

Vasily Dokuchaev, a Russian geologist, geographer and early soil scientist, is credited with identifying soil as a resource whose distinctness and complexity deserved to be separated conceptually from geology and crop production and treated as a whole.

Previous to Dokuchaev, 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-forming factors: climate, vegetation, country, relief and age. (Source: Krasilnikov, N.A. (1958) Soil Microorganisms and Higher Plants url:www.soilandhealth.org/01aglibrary/010112Krasil/010112krasil.intro.html)

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 material on the surface of the earth's moon 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".

Soil is always changing. The long periods over which change occurs and the multiple influences of change mean that simple soils are rare. While soil can achieve relative stability in properties for extended periods of time, the soil life cycle ultimately ends in soil conditions that leave it vulnerable to degradation.

Source: Soil. (2008, July 13). In Wikipedia, The Free Encyclopedia. Retrieved 16:52, July 16, 2008, from en.wikipedia.org/w/index.php?title=Soil

What is Soil Science?

Soil science is the study of soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.

Sometimes terms which refer to branches of soil science, such as pedology (formation, chemistry, morphology and classification of soil) and edaphology (influence of soil on organisms, especially plants), 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, agronomists, chemists, geologists, geographers, biologists, microbiologists, sylviculturists, sanitarians, archaeologists, and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences.

Source: Soil science. (2008, July 15). In Wikipedia, The Free Encyclopedia. Retrieved 16:48, July 16, 2008, from en.wikipedia.org/w/index.php?title=Soil_science

Note: NSCSS Members contributed the above soil and soil science content to Wikipedia in collaboration with WikiProject Soil.