A framework for estimating manure nitrogen balance and recycling potential for current and future conditions in the USA

Authors: WANG, YANYU - University Of Maryland Eastern Shore (UMES); ZHANG, XIN - University Of Maryland Eastern Shore (UMES); Spiegal, Sheri; DAVIDSON, ERIC - University Of Maryland Eastern Shore (UMES)

Submitted to: Nature Food
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2026
Publication Date: 3/9/2026
Citation: Wang, Y., Zhang, X., Spiegal, S.A., Davidson, E.A. 2026. A framework for estimating manure nitrogen balance and recycling potential for current and future conditions in the USA. Nature Food. 7:260–271. https://doi.org/10.1038/s43016-026-01312-5.
DOI: https://doi.org/10.1038/s43016-026-01312-5

Interpretive Summary: Livestock production has intensified globally to meet dietary demand, leading to manure nutrient loss to the environment that affects ecosystems and human health. Methods for estimating manure surplus, defined as the difference between available manure nutrients and crop nutrient requirements, vary widely, complicating decision-making for farmers and governments. This stufy compares existing analytical approaches and proposes a new indicator framework for standardzied calculation of manure exrection, nutrient losses, and crop assimilative capacity for improved decision-making at farm, county, and national scales.

Technical Abstract: Manure recycling can ameliorate pollution and fertilizer demand, but varying assumptions about recoverable manure nutrients and crop requirements complicate understanding of manure recycling potential. Using nitrogen (N) in the contiguous USA as a case study, we applied methods from six studies to compare manure N balance estimates (recoverable manure minus crop demand). We then developed a framework to assess both current and future potentials of manure recycling. The current balance in the USA is -13.3'±'1.1'TgN'yr-1, reflecting large crop demand currently met with synthetic fertilizer. Improved adoption of current manure management technologies could decrease this deficit by 5%, while future technologies could enable another 21% reduction. However, new manure N application should be reduced by 33–36% to avoid phosphorous (P) overapplication. Improved crop N efficiency could decrease the deficit by 27%. Applying this framework at county level demonstrates variable regional opportunities to improve manure recycling.