impact of trade policies on soil erosion in iran: subsidy or tax

macroeconomic policies lead to changes in farming system. these changes are accompanied by some most prominent factors that affect soil erosion. change in relative prices and its impact on soil erosion, via induced changes in crop patterns and agricultural practices, are related to policies implemented. one of the major goals of the present study is to emphasize on the flow of trade policies in domestic markets, which play as a linkage between upland and lowland areas, in determining an appropriate policy. in this study a general equilibrium approach was taken into account. results indicate that even though a 10% decrease in industrial import tariff will decrease soil erosion by more than an increase of 10% in the subsidy devoted to horticultural crops' export, nevertheless the latter policy increases the real gnp of the country more than the former policy does.