Effect of Deficit Irrigation on Selecting Optimal Crop Pattern under Water Crisis Conditions: A Case Study in Fars Province

In this study, the relationships between deficit irrigation with optimal cropping pattern was studied. This technique has been used widely, especially in regions facing water deficit. Since Fasa City of Fars Province is placed in warm climate and affected by water stress more than other climatic regions of the province, this city was selected as the study area. A nonlinear programming model with an aim to maximize net revenue was used subject to the yield response functions to water and other limitations. The results showed that there is the possibility of increasing income of representative farm by applying full irrigation instead of deficit irrigation in the current pattern and reducing cultivation to use the available water. In addition, in drought conditions, depending on the severity of the crisis and water restrictions, how to decide strategy for irrigation and land is different to the way if the level of water supply reduce to more than half of the current available water, the deficit irrigation strategy is the best options for optimal use of land and minimum available water. In this regard, farmer can reduce his gross margin reduction to a minimum by adopting yield reduction for some crops and changes in their cropping pattern in accordance with their marginal revenue of each unit of water consumption