SOIL PROFILE

Soil profile is a vertical section of the soil through all its horizons and extends up to the parent materials. The soil profile consists of the weathered material derived from the rock. But the parent material itself does not form a part of it. Nor has it any horizontal layers termed as horizons. A soil profile generally has four main horizons in it-true soil at the top (Horizon A), subsoil (Horizon B), weathered rock (Horizon C) and bedrock (Horizon D). Each horizon is quite distinct from the other with its own physical and chemical composition.

Horizon' A; may consist of sub-horizons richer in organic matter intimately mixed with mineral matter. There is loss of clay, iron or aluminium due to high concentration of quartz. In Horizon 'B', there is a dominant concentration of clay, iron, aluminium, of humus alone or in combination. The 'C' Horizon excludes the bedrock from which' A' and 'B' Horizons are presumed to have been formed.
The soil profile reveals the surface and the sub-surface characteristics and qualities- depth, texture, structure, drain­ age conditions and soil-moisture relationships-of the soil which directly affect plant growth. Hence, its study is important from the viewpoint of crop husbandry. The soil profile is taken as a unit of study which helps 'the inves­tigators both to classify the soils and to understand soil­moisture-plant relationships. The study of soil profile thus - furnishes a base which has to be supplemented by physical, chemical and biological properties of the soils.