Environmental efficiency of rainfed and irrigated wheat crops in Spain. A stochastic DEA metafrontier approach
研究了西班牙不同地区雨养和灌溉小麦作物的环境效率，使用随机DEA元前沿方法比较两组技术的差距，识别出最佳实践区域和需要改进的区域。
Abstract This paper studies the environmental efficiency of wheat crops in the different regions of Spain where it is grown. Both rainfed and irrigated wheat cropping systems are considered. Excepting irrigation water consumption, the two groups of observations share the same inputs (namely, N Fertilizers and Non-renewable energy) and outputs (namely, Yield, soil organic carbon, NH 3 emissions, NO 3 − leaching and Global Warming Potential). The three undesirable outputs considered are handled using the transformation method. Given the stochastic character of the variables, a Chance Constrained DEA approach is proposed. A non-radial directional distance function (DDF) model is used. The proposed approach provides deterministic efficiency, stochastic targets and reference units. The two groups of observations are compared using a metafrontier approach and the corresponding technology gap ratios are computed. For each group of observations, the results have identified the best practice regions and those where environmental efficiency improvements are needed.