Economics of irrigation water mixing within a farm framework

Linear programing models, deterministic in the short run and stochastic (random rainfall) in the long run, aimed at guiding annual decision making with regard to crop mix and saline irrigation water mixing from various sources within a farm framework, are presented. The short-run model incorporates the physical, biological, and economic relationships involved in one endogenous system and enables an in depth analysis of them but is limited to a single year. The long-run model considers the effects of the short-run decisions on the future but several relationships are incorporated exogenously. The short run model's results are utilized for the determination of some of these predetermined relationships. The models are applied to a potential farm situation in southern Israel. The results provide priorities in the allocation of water and soil plots of varying salinity levels and empirical estimates of the shadow prices and the rates of substitution between the limited resources.