The main aim of soil conservation is to prevent the loss of the precious top soil from erosion and to maintain it in a fertile state for agricultural purposes. To achieve these aims a variety of methods are employed which can be grouped into the following two categories:
(1) Biological Methods:
Biological methods primarily involve stimulation of plant growth (grasses, bushes or trees) over the denuded area. Roots of these plants securely bind the soil while the crowns of bushes and trees offer impediments to the flow of air or water currents. Dead plant parts provide organic material to the soil which in turn improves soil texture and fertility.
Strip fanning practiced on flat denuded area involves plantation of crops in narrow strips which alternate with strips containing soil protecting plants – bushes or tress. On hill slopes contour farming is practised which involves farming on level steps carved across the slope. Reforestation – plantation of trees on bare land not used for agriculture around and in between the agricultural fields is very helpful in checking degradation of the soil. It provides a moderating influence on the local climate and is exceedingly helpful in conserving the soil.
(2) Mechanical Methods:
Most of the mechanical methods are aimed at checking the rapid flow of air currents or surface flow of water and increasing the rate of water percolation downwards to subsurface layers. Contour terracing, making trenches, erection of barriers to the flow of water and air currents, breaking the underground pan or basin to enhance downward percolation of water are some of the common practices.
In fact, it is a combination of biological and mechanical methods which are commonly used to halt degradation and erosion of soils.