determination of iran's agricultural optimal r&d expenditure

r&d; is one of the most important and suitable strategies government’s policies for increasing of agricultural production and supply. in this study, in addition of economic evaluation of agricultural r&d; and determination of its rate of return, optimal iran’s agricultural r&d; expenditure is determined. so, in this article, ex-post and ex-ante evaluation by using of mathematical programming approach are used for determination and evaluation of agricultural r&d; expenditure for years of 1967-2007. estimation of optimal r&d; expenditure indicate that optimal r&d; budget is 23.5 percent more than current r&d; budget and optimal optimal supply is 14.4 percent more than current supply. results indicate that rate of return for current agriculture r&d; is 29.12 percent. whereas added r&d; rate of return respect to current r&d; is 38.35 percent.