In general, soil is defined as the more or less loose and crumby part of the outer earth crust. It is a natural dynamic body of mineral and organic constituents, differentiated into horizons, which differs among themselves as well as from the underlying parent material in morphology, physical make-up, chemical composition and biological characteristics. It is made up of small particles of different sizes.
Soil is a three-dimensional body, which supports plant establishment and growth and it is a natural and dynamic medium. For a farmer, soil refers to the cultivated top layer (surface soil) only, that is, up to 15–18 cm of the plough depth. Soils widely vary in their characteristics and properties. Understanding the properties of soils is important (1) for optimum use they can be put to and (2) for best management requirements for their efficient and productive use.
Functions of soil
• It provides place and anchorage for plant growth and development.
• It serves as a medium for air and water circulation.
• It acts as a reservoir for water and nutrients.
• It provides space for beneficial microorganisms.
Pedology – The origin of the soil, its classification and its description are involved in pedology.
Pedologist considers soil as a natural body and does not focus primarily on the soil’s immediate practical utilization. Pedologist studies, examines and classifies soil as they occur in their natural environment.
Edaphology – It is the study of soils from the standpoint of higher plants. It considers various properties of soil as they relate to plant production. The edaphologist is practical, having the production of food and fibre as an ultimate goal. Simultaneously, the edaphologist must be a scientist to determine the reasons for variations in the soil productivity, and to find means of conserving and improving soil productivity