Tackling policy leakage and targeting hotspots could be key to addressing the ‘Wicked’ challenge of nutrient pollution from corn production in the U.S.

Abstract

Reducing nutrient loss from agriculture to improve water quality requires a combination of management practices. However, it has been unclear what pattern of mitigation is likely to emerge from different policies, individually and combined, and what the consequences would be for local and national land use and farm returns. We address this research gap by constructing an integrated multi-scale framework for evaluating alternative nitrogen loss management policies for corn production in the US. This approach combines site- and practice-specific agro-ecosystem processes with a grid-resolving economic model to identify locations that can be prioritized to increase the economic efficiency of the policies. We find that regional measures, albeit effective in reducing local nitrogen loss, can displace corn production to the area where nitrogen fertilizer productivity is low and nutrient loss rate is high, thereby offsetting the overall effectiveness of the nutrient management strategy. This spatial spillover effect can be suppressed by implementing the partial measures in tandem with nationwide policies. Wetland restoration combined with split fertilizer application, along with a nitrogen loss tax could reduce nitrate nitrogen loading in the Mississippi River by 30% while only increasing corn prices by less than 2%.

Focus on global–local–global analysis of sustainability

“…Papers in this special issue touch on all aspects of these criteria. For example, Liu et al (2023) found that wetland restoration was the most effective in reducing nitrate loss in the Mississippi Basin, but installing controlled drainage was the most efficient (i.e., nitrate loss per $ invested). Both Liu et al (2023) and Haqiqi et al (2023b) find that coupled strategies, that are often synergistic, are much more effective in achieving sustainability goals compared to single strategies.…”

“…For example, Liu et al (2023) found that wetland restoration was the most effective in reducing nitrate loss in the Mississippi Basin, but installing controlled drainage was the most efficient (i.e., nitrate loss per $ invested). Both Liu et al (2023) and Haqiqi et al (2023b) find that coupled strategies, that are often synergistic, are much more effective in achieving sustainability goals compared to single strategies. The study by Ray et al (2023) finds that, under a restricted labor mobility situation, regions targeted for the sustainable groundwater use policy will see sharp decrease in wages, but the spillover effects will increase wages in non-targeted regions.…”

“…Several studies in this special issue (Liu et al 2023, Ray et al 2023, Haqiqi et al 2023a) use an integrated modeling framework to simulate such local responses and feedbacks between scales. These studies integrate gridded biophysical models (hydrological models, crop models) with a global economic model that resolves grid-level responses in the region(s) of interest.…”

“…These responses are aggregated back to the national or global level and fed to the global economic model, which calculates changes in input and commodity prices, and implications for both farmer and consumer responses, which further feedback to the pixel-level. Liu et al (2023) use such a modeling framework to evaluate the influence of US national policies to reduce nitrogen (N) losses from fertilizer application on corn. They investigate the impact of four policies: a national tax on N loss; improving N-use efficiency; controlled drainage, and wetland restoration.…”

“…Many of these papers stress the importance of integrating across climate, ecology, economics, hydrology, land use models, among others. Liu et al (2023) combine an economic model (SIMPLE-G) with an agro-ecosystem model (Agro-IBIS) to analyze the effects of policies to manage nitrogen runoff from agriculture on water quality and agricultural markets. Troy et al (2023) discuss the linkages of water quality and quantity with agricultural markets, land use, ecosystems, and health impacts, and describe an approach for improving the sustainability of agricultural water systems.…”