Reducing Nitrogen Losses in US Row-Crop Agriculture: Challenges, Solutions, and Policy Pathways

This Working Paper is part of Food, Freshwater and Climate. Reach out to Mike Badzmierowski for more information.

This working paper argues that improving nitrogen management in the United States (U.S.) row-crop systems is essential for public health, climate mitigation, water quality, and farm profitability. It documents that nitrous oxide from agricultural soils accounts for roughly half of U.S. agricultural greenhouse gas (GHG) emissions and that the combined footprint of soil emissions and fertilizer production was approximately 346 million tonnes (Mt) of carbon dioxide equivalents (CO₂e) in 2022. The paper also summarizes other key nitrogen loss pathways in agriculture, such as ammonia emissions and nitrate losses, that harm air quality and water resources and reduce on-farm nitrogen use efficiency.

The paper's technical core is a practical toolkit to reduce losses while maintaining yields. Recommended actions include annual soil testing, precision and variable-rate application, shifting fall applications to spring or later in the growing season, targeted use of nitrification and urease inhibitors, improved drainage and irrigation management, accounting for nitrate in irrigation water, and wider use of cover crops. The author also notes that reducing dependence on very nitrogen-intensive end uses such as corn for ethanol would lower total losses.

Since a small share of cropland drives most of the national nitrogen surplus, the paper recommends focusing early efforts in hotspot regions identified by previous research.

To scale results, the author proposes a philanthropy-backed Coalition for Limiting Excess Agricultural Reactive Nitrogen (CLEAR) to coordinate funding, data, and verification. The paper also outlines a federal National Nitrogen Initiative that updates NRCS Practice 590 with a streamlined "590 N" tier and ties payments to verified outcomes using both nitrogen use efficiency and nitrogen balance to avoid efficiency gains that mask overapplication.

Overall, the paper endorses a performance focused, public-private framework with rigorous monitoring, measurement, reporting, and verification that rewards measurable reductions in surplus and loss while protecting yields and farm livelihoods.

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