Change from the purchasing price policy to the guaranteed price policy and its effects on cropping pattern in Qazvin plain

In the present study the effects of purchasing and guaranteed price policy instruments and also change from the purchasing price policy to the guaranteed price policy was examined on cropping patterns, farmers' income and consumption of inputs in Qazvin Plain. To achieve this goal, using a two-stage random sampling method 246 farmer Selected and then through survey and complete the questionnaire the required information was collected in 1395. For modeling and analysis of information’s the positive mathematical programming model (PMP) with the cost function approach was used and effect of purchasing and guaranteed price policy instruments under three scenarios continue purchasing and guaranteed price policies in its current form, the implementation of the purchasing policy in the form of a purposive and replacement the purchasing policy with a guaranteed price was evaluated. The results of this study showed that in all three scenarios the area under cultivation of water-saving products special, wheat decrease, and instead the Area under cultivation of Products with high water demand such as alfalfa and tomato has been increased