Biological Properties of Soils

A large number of organisms live in the soil. They perform a variety of functions for their growth and reproduction. For these functions of soil organisms, soils behave like a living entity. Soil components photosynthesize, respire, and reproduce. In addition, they produce organic matter, consume organic matter, and decompose them. Some of them burrow in the soil, make spaces for their accommodation and movement, and mix surface and subsoil materials together. Soil becomes a dynamic body for the activity of soil organisms. The changes that are caused by soil organisms have their impact on soil fertility and productivity. A sterile soil is not a soil in the real sense. Although soil biota, which includes living roots and soil organisms, occupies a very small fraction of the total soil volume (<0.5 %), it has tremendous influences on soil properties and soil processes. However, soil organisms are usually the most active in the surface soil zone of 0–15 cm, because this zone has accumulation of organic residues and available nutrients. Soil depth, organic matter and nutrients, microclimate, and physical and chemical soil environment influence the structure and function of soil biota.