Cropping Systems for Utilization of Saline-Sodic Irrigation Waters

Cropping systems that include the sequential reuse of saline-sodic drainage waters could be a key component of irrigation sustainability along the Westside San Joaquin Valley in California. In this irrigated region, where there is no regional drainage outlet, such cropping systems could facilitate the installation of artificial drainage on 304,000 ha of lands with shallow water tables and reduce the volume of drainage water currently disposed in underground soil strata, or in evaporation ponds. The electrical conductivities of salinity of drainage waters on the Westside range from 6 to 20 dS/m, SARs range from 6 to 35, and the boron contents in 80 % of the drainage waters are less than 14 mg/L, with 50 % having less than 4 mg/L. Although these water quality characteristics limit the crops that can be grown, salt tolerant forages, trees, and shrubs provide options for sequential reuse. Sequential reuse of drainage water may eliminate the need for evaporation ponds by storing the remaining drainage water in soil strata beneath lands dedicated to the production of salt tolerant forages. A similar process occurs now beneath irrigated lands without artificial drainage, but on a much larger area. Alternatively, if fields receiving saline drainage water were artificially drained, the evaporation pond area needed could be decreased by at least a factor of five, or the capacity requirements of a regional drain reduced, if one were ever built.