Soil Business

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion. Soil is different from its parent rock(s) source(s), altered by interactions between the lithosphere, hydrosphere, atmosphere, and the biosphere. It is a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states. Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain sol solution (liquid) and air (gas). Accordingly, soils are often treated as a three state system. Most soils have a density between 1 and 2 g/cm³. Soil is also known as earth: it is the substance from which our planet takes its name. Little of the soil composition of the earth is older than Tertiary and most no older than Pleistocene.

Soil formation, or pedogenesis, is the combined effect of physical, chemical, biological, and anthropogenic processes on soil parent material. Soil genesis involves processes that develop layers or horizons in the soil profile. These processes involve additions, losses, transformations and translocations of material that compose the soil. Minerals derived from weathered rocks undergo changes that cause the formation of secondary minerals and other compounds that are variably soluble in water, these constitutes are moved (translocated) from one area of the soil to other areas by water and animal activity. The alteration and movement of materials within soil causes the formation of distinctive soil horizons. The weathering of bedrock produces the parent material that soils form from. An example of soil development from bare rock occurs on recent lava flows in warm regions under heavy and very frequent rainfall.

The material from which soils form is called parent material, they include: weathered primary bedrock, secondary material transported from other locations, e.g. colluvium and alluvium, deposits that are already present but mixed or altered in other ways - old soil formations, organic material including peat or alpine humus, anthropogenic materials - like landfill or mine waste. Few soils form directly from the underlying rocks they develop on. The soils that do form directly from the breakdown or weathering of rocks are often called “residual soils” and they have the same general chemistry as their parent rocks. Most soils are derived from materials that have been transported from other locations by the wind, water and gravity.

Soil formation is greatly dependent on the climate, and soils from different climate zones show distinctive characteristics. Temperature and moisture affect weathering and leaching. Wind moves sand and other particles from one location to another, especially in arid regions where there is no or little plant cover. The type and amount of precipitation influence soil formation by affecting the movement of ions and particles through the soil, aiding in the development of different soil profiles. Seasonal and daily temperature fluctuations affect the effectiveness of water in weathering parent rock material and affect soil dynamics, freezing and thawing is an affective mechanism to break up rocks and other consolidated materials. Temperature and precipitation rates affect biological activity, rates of chemical reactions, and types of vegetation cover.