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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #365590
Research Project: Sustainable and Resilient Cropping Systems for Midwestern Landscapes

Location: Agroecosystems Management Research

Title: Crop yield and nitrous oxide emissions following swine manure application: A meta-analysis

Author
item LUO, WEIQUAN - Iowa State University
item O'Brien, Peter
item Hatfield, Jerry

Submitted to: Agricultural & Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2019
Publication Date: 9/12/2019
Citation: Luo, W., O'Brien, P.L., Hatfield, J.L. 2019. Crop yield and nitrous oxide emissions following swine manure application: A meta-analysis. Agricultural & Environmental Letters. 4(1):190024. https://doi.org/10.2134/ael2019.07.0024.
DOI: https://doi.org/10.2134/ael2019.07.0024

Interpretive Summary: Swine production is an important part of the world economy and contributes to global food security, and millions of tons of swine manure are produced each year as part of this industry. This manure contains nutrients that can be used to grow crops, so it is often applied as fertilizer. However, applying manure to farmland may create a risk to air, soil, and water quality. The objective of this research was to analyze findings from 39 studies to compare use of swine manure as fertilizer with traditional fertilizer when measuring crop yield and nitrous oxide emissions. Neither crop yield nor nitrous oxide emissions were different in fields using swine manure from those using synthetic fertilizer. However, the analysis highlighted several conditions under which swine manure may decrease yield, such as in clay soils or when the manure is applied to the surface. Although nitrous oxide emissions were not affected by swine manure application, the high variability in the data suggests that increased emissions are possible. Overall, these results show that swine manure can be used as fertilizer to produce crop. This finding is important because it may reduce the costs of both purchasing other fertilizer and disposing of the manure. However, the manure must be applied with caution and at the appropriate rates so that it does not negative impact soil, air, or water quality.

Technical Abstract: Swine manure has potential for reuse as fertilizer on cropland and pastureland. Currently, producers may be hesitant to land apply swine manure because information regarding the impacts to crop production and environmental quality has been inconsistent. The objective of this research was to synthesize the literature investigating impacts of swine manure application on crop yield and soil nitrous oxide emissions as compared to synthetic fertilizer. Overall, the meta-analysis of 39 studies shows that swine manure does not affect either crop yield or nitrous oxide emissions. However, a moderator analysis indicated that crop yield using manure fertilizer may be adversely affected in fine-textured soils or when applied to the soil surface. While these results suggest that swine manure may be safely applied as fertilizer, producers should still be cautious with how manure is applied to capture its N value without yield losses or detrimental effects to environmental quality.