Write a short note on ‘composition of soil.


Composition of soil depends on the nature of parent rock and the quantity and type of organic materials present in it. The following components are generally found in a soil:

(1) Inorganic substances: Most of the inorganic substances, present in the soil, are derived from the parent rock.

(2) Organic material (Humus): Humus increases the productivity and water holding capacity of the soil.

(3) Soil water: It is generally present in the spaces between the soil particles. The water content of a soil has a significant effect on plant productivity.

(4) Soil air: Spaces, between the soil particles, contain air. Well aerated soils are associated with healthy roots that increase crop productivity. Soil air is important for the respiration of roots. 

(5) Living organisms: A variety of organisms are found in soil. They include micro-organisms like bacteria, fungi and algae.