COMPUTER-MODEL FOR MANAGING SALINE WATER FOR IRRIGATION AND CROP GROWTH - PRELIMINARY TESTING WITH LYSIMETER DATA

A computer model was developed to help formulating irrigation strategies for areas where use of saline waters of questionable quality may be an option for crop production. The model estimates salt and water balance in the soil profile and predicts crop growth in response to weather and irrigation and crop rotation management. Salinity effects on crop growth are simulated in the model through inclusion of osmotic potential in the determination of water uptake. However, it was found that osmotic potential alone did not explain reduced crop growth under heavy and frequent irrigation. Salinity effects on root permeability were found to satisfactorily explain reduced water uptake and growth under such conditions. The model was calibrated and tested for wheat and sorghum crops using one year's data from column lysimeters irrigated with water of varying qualities at the U.S. Salinity Laboratory at Riverside, California. The calibrated model was found to reasonably predict water use, soil salinity, and crop production of independent test lysimeters. Although the model appears to have potential for analyzing irrigation strategies in agricultural systems with salinity constraints, additional testing with field data will be required.