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Countries influence the trade-off between crop yields and nitrogen pollution

Abstract

National institutions and policies could provide powerful levers to steer the global food system towards higher agricultural production and lower environmental impact. However, causal evidence of countries’ influence is scarce. Using global geospatial datasets and a regression discontinuity design, we provide causal quantifications of the way crop yield gaps, nitrogen pollution and nitrogen pollution per crop yield are influenced by country-level factors, such as institutions and policies. We find that countries influence nitrogen pollution much more than crop yields and there is only a small trade-off between reducing nitrogen pollution and increasing yields. Overall, countries that cause 35% less nitrogen pollution than their neighbours only show a 1% larger yield gap (the difference between attainable and attained yields). Explanations of which countries cause the most pollution relative to their crop yields include economic development, population size, institutional quality and foreign financial flows to land resources, as well as countries’ overall agricultural intensity and share in the economy. Our findings suggest that many national governments have an impressive capacity to reduce global nitrogen pollution without having to sacrifice much agricultural production.

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Fig. 1: Revealing borders.
Fig. 2: Spatial distributions of nitrogen balances, water pollution, yield gaps and the natural vegetation potential around international borders.
Fig. 3: Estimated effect of countries on their yield gaps and nitrogen pollution.
Fig. 4: Countries’ estimated effect on their yield gaps versus their nitrogen pollution.
Fig. 5: Explaining countries’ estimated pollution versus yield gaps effects.

Data availability

Data can be retrieved from Wuepper et al.46 and from the corresponding author upon reasonable request

Code availability

Code can be retrieved from Wuepper et al.46 and from the corresponding author upon reasonable request

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D.W. conceived the project, prepared some of the data, and carried out the analysis. S.L.C. prepared most of the data. All authors contributed to the analysis and writing the manuscript.

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Correspondence to David Wuepper.

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Supplementary Figs. 1–6 and a discussion of our main explanatory variables and their data sources.

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Wuepper, D., Le Clech, S., Zilberman, D. et al. Countries influence the trade-off between crop yields and nitrogen pollution. Nat Food 1, 713–719 (2020). https://doi.org/10.1038/s43016-020-00185-6

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