Rate of Water Intake of the Soil Under Different Soil Treatments

Abstract

NE of the essentials of water and soil conservation is to encourage the entry of the largest amount of water into the soil. Water entering the soil is usually accounted for in the following ways: (1) movement downwards towards the water table, (2) storage in the upper layers of the soil to account for plant use and transpira- tion, and (3) loss from the soil surface as eva- poration. Infiltration or water intake is the movement of water from the surface into the soil. Percolation water or gravitational water is that part of intake water which moves downward in response to gravity and reaches the water table. The maximum rate of water intake of a soil is called its infiltration capa- city. As a result of absorption or sorption, a part of intake water is retained in the soil through the direct and indirect effects of capillary or molecular forces. Capillary water held within the capillary pores in spite of the pull of gravity is mobile and at the same time much of it is available to plants. This is available soil water. Hy- groscopic water or unavailable soil moisture is held with tremendous forces in the form of thin films around or in soil particles. Apart from the amount of water evaporated from the surface of vegetation, it is the in- filtration capacity of the soil that determines the runoff. Hence the infiltration capacity or the ability of the soil to absorb water has been the subject of much interest and is an important factor in determining runoff