Salt Balance and Leaching Efficiency in Farm Irrigation Systems

An equation to predict the average salt concentration of drainage water has been developed. The equation has been tested using published data for various leaching situations and has been used in developing an expression for predicting leaching efficiency. The leaching efficiency equation has been tested for its validity using input-output data from various irrigation projects. Leaching efficiency could be improved over a period by allowing leaching of soluble salts with rainfall. An expression to take care of leaching by rain water to maintain salt balance in the root-zone has been proposed and its use has been explained using field examples.