Salt and Water Balance, Coachella Valley, California

The salt balance index (output/input) for the irrigated land of Coachella Valley during 1957-1965 was highly related to both the area of irrigated land having tile drainage and the leaching percentage, the index becoming close to one when about half the land became tiled and when the leaching percentage increased to about 30. At salt balance evapotranspiration, taken as the difference between depths of applied and drainage water, agreed within about 10% of that calculated by the Blaney-Criddle formula. About 10% of the applied salt appears to precipitate in the soil largely as calcium carbonate, and calcium and magnesium in water replaces exchangeable sodium in soil during irrigation operations.