The phantom menace in agriculture: How lagged droughts distort input decisions and create environmental deadweight loss
Journal of Development Economics · 2026 · Dingqiang Sun、Xueting Qie、Kaixing Huang
中文摘要
化肥过量施用在全球范围内损害生态系统和人类健康。本研究识别出化肥过量施用的一个显著且新颖的相关因素：农户对滞后干旱的反应。利用中国玉米生产独特的地块层面数据，我们发现，尽管任一年度的干旱冲击相互独立，但上一年度发生干旱会使本年度的化肥施用量增加17.6%，却不会对产量产生正向影响。简单外推表明，这种行为反应可能导致中国每年化肥过量施用总量达到115万吨，相当于5.09亿美元的货币成本、影响20亿至70亿立方米水体的水污染，以及930万吨的碳排放。尽管我们无法区分化肥过量施用究竟源于行为偏误，还是对干旱后土壤氮素可利用性可能下降的反应，但化肥施用增加并未带来产量收益这一发现，加之气候变化下干旱频率预计上升，凸显了采取缓解措施的紧迫性。我们识别出应对这一复杂问题的若干关键途径，包括投资灌溉、通过土地整合将土地集中于高生产率农户，以及推广耐旱作物品种；无论其根本原因是行为偏误还是农艺上的必要性，这些途径均适用。
Abstract
Excessive chemical fertilizer use damages ecosystems and human health globally. This study identifies a significant and novel correlate of fertilizer overuse: farmers’ responses to lagged droughts. Employing unique plot-level data from maize production in China, we find that while drought shocks in any given year are independent, a drought in the previous year increases fertilizer use in the current year by 17.6%, with no positive effect on yield. A simple extrapolation suggests this behavioral response could account for an annual total fertilizer overuse of 1.15 million tons in China, translating to a monetary cost of 509 million USD, water pollution affecting 2–7 billion m 3 , and carbon emissions of 9.3 million tons. While we cannot distinguish whether the fertilizer overuse is due to behavioral bias or a response to potentially lower soil nitrogen availability following a drought, the finding that the increased fertilizer use provides no yield benefit, combined with the projected increase in drought frequency under climate change, underscores the urgent need for mitigation. We identify investment in irrigation, land consolidation toward high-productivity farmers, and the promotion of drought-tolerant crop varieties as key approaches to addressing this complex issue, whether its root cause is behavioral bias or agronomic necessity.