Incomplete markets, crop portfolios, and agricultural productivity
利用乌干达全国面板调查,我记录了以下事实:农民面临作物产量与风险之间的权衡;大多数农民同时种植高产作物和低产作物;较贫困的农民集中于低产、低风险的作物。随后,我构建了一个包含作物组合选择的不完全市场模型,其中家庭在收入回报与消费平滑之间进行权衡。财富匮乏的家庭最优地对中间投入品投资不足,并转向更安全的作物。作物组合、中间投入品使用与财富分布在均衡中联合决定。该模型还再现了收入不平等和收入波动向消费的低传导。将模型校准至乌干达农村后,结果表明补全市场可使农业生产率提高12.8%,其中15.8%的增益来自消除投入品在农户之间和作物之间的错配。消费提高17.6%,福利提高17.4%,收入不平等小幅上升,而消费不平等保持不变。
英文原文
Using the Uganda National Panel Survey, I document that farmers face a trade-off between crop yields and risk, that most grow both high- and low-yield crops, and that poorer farmers concentrate on the low-yield, low-risk ones. I then develop an incomplete-markets model with a crop-portfolio choice, in which households trade off income returns against consumption smoothing. Wealth-poor households optimally under-invest in intermediates and shift toward safer crops. Crop portfolios, intermediate input use, and the wealth distribution are jointly determined in equilibrium. The model also reproduces the low pass-through of both income inequality and income volatility into consumption. Calibrated to rural Uganda, it implies that completing markets raises agricultural productivity by 12.8%, with 15.8% of the gain coming from eliminating the misallocation of inputs across farmers and crops. Consumption rises by 17.6% and welfare by 17.4%, with income inequality rising slightly and consumption inequality unchanged.