Large quantities of saline water frequently exist in irrigated areas of the world. Various strategies have been proposed to use these saline waters. Blending involves mixing saline water with good quality water to an acceptable salinity and then using this water to irrigate crops. The cyclic strategy uses waters of various salinities separately either during one season or in a crop rotation as a function of the crop's salt tolerance. A multi-seasonal transient state model, known as the modified van Genuchten-Hanks model, was used to investigate the effects of cyclic or blending application of irrigation waters of two salinity levels on alfalfa (Medicago sativa L.), and on a corn (Zea mays L.) and cotton (Gossypium hirsutum L.) crop rotation. Simulated alfalfa yields were similar for the cyclic and blending strategies that applied the same amount of salt and water. The cyclic strategy produced higher simulated yields of salt-sensitive corn than the blending strategy, whereas the simulated salt-tolerant cotton yield was not affected by the two strategies. The beneficial effects of the cyclic strategy on corn production decreased under deficit irrigation.
High quality irrigation water is a limited natural resource in semiarid areas of the world. However, large quantities of saline water frequently exist, often as ground water. Potentially, these saline waters can be used to supplement high quality irrigation water. Use of saline water for irrigation may also provide a means of partially disposing of drainage water. Drainage water disposal often creates problems. For example, in the San Joaquin Valley, California drainage water has been disposed of in evaporation ponds or discharged into streams. Placement in evaporation ponds has lead to the concentration of trace elements contained in the drainage water to toxic levels. Elements such as selenium have been linked to wildfowl deaths and deformation (Ohlendorf 1989). Evaporation ponds also take productive crop lands out of service.