Soil Profile

Soil is comprised of distinct layers which are called soil horizons. All soil horizons taken together form soil profile. Fig. 8.1 below shows different horizons of soil with increasing depth.

Fig 8.1: Soil Profile

The top layer or 'A' horizon is several inches in thickness. This layer is most important for vegetation and agricultural crops as it is rich in humus. Deforestation over the years is responsible for the loss of topsoil leading to considerable decrease in the agricultural crops.

The next layer is ‘B’ horizon and is also known as sub soil. It receives organic matter, salts and clay particles by leaching from the topsoil. It contains little humus also. Below ‘B’ Horizon is the ‘C’ Horizon which is composed of weathered parent rocks from which the soil originated. The lowest layer is hard zone of rocks called bedrocks.

8.5