Deficit irrigation simultaneously with reduced available water the solution to conservation of water resources in Qazvin plain

In the present study first the agricultural production functions was estimated based on three techniques of full irrigation and deficit irrigation 5 and 10 percent in order to presentation of the practical solution to conservation of surface and underground water resources in Qazvin plain. The optimal amounts of cropping pattern were determined in Qazvin province by a non-linear programming model. Then, the effects of deficit irrigation was investigated on cropping pattern, water used and farmer’s gross marginal simultaneously with reduced available water under scenarios 10, 20, 30 and 40 percent. To estimating of the agricultural production functions was used Ordinary Least Squares method and Eviews software. The non-linear programming model was solved in GAMS software. The results of estimated production functions showed that deficit irrigation 5 percent creates a slight decrease in products yield. But, deficit irrigation 10 percent has the negative effect on yield of most products. The results of non-linear programming model showed although use of deficit irrigation 5 percent simultaneously with reduced available water policy creates the slight decrease in farmer’s gross marginal but this technique helps to maintain and sustainability of surface and underground water resources of Qazvin plain strongly.