Study Quantifies How Aquifer Depletion Threatens Crop Yields

In the heart of America's breadbasket, where expansive fields of corn and soybeans stretch across the landscape, a new study from the University of Nebraska sheds light on a critical issue threatening agricultural sustainability: the depletion of aquifers. Published in the journal Nature Water, the study draws on three decades of data to reveal the intricate relationship between aquifer thickness, irrigation, and crop yields, ultimately highlighting the precarious future of food production amid escalating drought and changing climate conditions.

The study primarily focused on the High Plains Aquifer, the largest aquifer in the United States, spanning eight states, including the majority of Nebraska. Groundwater from this aquifer is a lifeline for many farmers, especially in regions where precipitation alone cannot sustain crops. The research team, led by Taro Mieno, an associate professor of agricultural economics, discovered that the depletion of an aquifer poses a significant threat to crop yields, even when it appears to have sufficient water for irrigation.

Nick Brozović, the director of policy at the Daugherty Water for Food Global Institute, emphasized the critical implications of this research. He explained that as aquifers thin out, small changes in thickness have disproportionately large impacts on crop production and resilience. This phenomenon is particularly challenging to predict because traditional models often rely on past experiences, leading to underestimations of the severity of future challenges.

The study analyzed data from the High Plains Aquifer, including aquifer thickness estimates since 1935, county-level yields of corn and soybeans from 1985 to 2016, and meteorological data to calculate seasonal water deficits. The findings revealed that aquifer depletion significantly affects irrigated agriculture, with the thickness of the aquifer playing a crucial role in determining the resilience of crops during drought conditions.

Notably, the research highlighted the economic and resilience consequences of aquifer depletion. Even in areas with seemingly abundant water, the ability to meet crop water needs diminishes as aquifers deplete. This has a cascading effect on agricultural productivity and exacerbates the challenges faced by farmers, especially during extreme water deficits.

The study also underscored the importance of effective water management policies. Farmers above the most saturated sections of the aquifer continued to achieve high irrigated yields during extreme water deficits. However, those depending on less saturated areas experienced a decline in irrigated yields even with comparatively smaller water deficits.

As the world grapples with the impacts of climate change, the study emphasizes the increasing importance of aquifers for sustaining agriculture. The researchers predict that as climate change intensifies, the demand for irrigation will rise, leading to faster aquifer depletion and exacerbating the challenges faced by farmers.

While Nebraska has established governance systems to manage its aquifers effectively, the study calls for a reevaluation of existing policies. Brozović stressed the need to consider aquifer saturation levels and extraction capabilities, not just pumping regulations, to ensure sustainable water use for agriculture.

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