Observational evidence for groundwater influence on crop yields in the United States

• 成果类型: Article
• 署名作者: Deines, Jillian M.; Archontoulis, Sotirios, V; Huber, Isaiah; Lobell, David B.
• 署名单位: Stanford University; United States Department of Energy (DOE); Pacific Northwest National Laboratory; Iowa State University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13437
• DOI: 10.1073/pnas.2400085121
• 发表日期: 2024-09-03
• 关键词: water tables; maize; corn; patterns; moisture; IMPACT; depth; iowa

摘要

As climate change shifts crop exposure to dry and wet extremes, a better understanding of factors governing crop response is needed. Recent studies identified shallow groundwater-groundwater within or near the crop rooting zone-as influential, yet existing evidence is largely based on theoretical crop model simulations, indirect or static groundwater data, or small- scale field studies. Here, we use observational satellite yield data and dynamic water table simulations from 1999 to 2018 to provide field- scale evidence for shallow groundwater effects on maize yields across the United States Corn Belt. We identify three lines of evidence supporting groundwater influence: 1) crop model simulations better match observed yields after improvements in groundwater representation; 2) machine learning analysis of observed yields and modeled groundwater levels reveals a subsidy zone between 1.1 and 2.5 m depths, with yield penalties at shallower depths and no effect at deeper depths; and 3) locations with groundwater typically in the subsidy zone display higher yield stability across time. We estimate an average 3.4% yield increase when groundwater levels are at optimum depth, and this effect roughly doubles in dry conditions. Groundwater yield subsidies occur -35% of years on average across locations, with 75% of the region benefitting in at least 10% of years. Overall, we estimate that groundwater- yield interactions had a net monetary contribution of approximately $10 billion from 1999 to 2018. This study provides empirical evidence for region- wide groundwater yield impacts and further underlines the need for better quantification of groundwater levels and their dynamic responses to short- and long- term weather conditions.