|DUNCAN, EMILY - Pennsylvania State University|
|BEEGLE, DOUGLAS - Pennsylvania State University|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2016
Publication Date: 1/12/2017
Citation: Duncan, E., Dell, C.J., Kleinman, P.J., Beegle, D. 2017. Nitrous oxide and ammonia emissions from injected and broadcast applied dairy slurry. Journal of Environmental Quality. 46:36-44. https://doi.org/10.2134/jeq2016.05.0171.
Interpretive Summary: Injection of manures into soil provides many environmental and agronomic benefits including reduced ammonia volatilization, phosphorous runoff, and odor emission. However, a limited number of studies in Europe have shown an increased potential for emissions of the potent greenhouse nitrous oxide with manure injection. This study compared ammonia and nitrous oxide emissions between shallow disk injection and unincorporated broadcast application of liquid dairy manure in the northeastern US. Shallow disk injection consistently reduced ammonia emission by more than 90 percent but increased nitrous oxide emission by up to 150 percent. While amount of nitrogen lost as nitrous oxide has little impact on the quantity of N available to the crop (less than 2 percent of the total N applied), small increases in nitrous oxide emission negatively impact efforts to mitigate climate change. Continued research is needed to reduce the amount of greenhouse gas emitted while retaining the multiple benefits of shallow disk injection.
Technical Abstract: Trade-offs associated with surface application or injection of manure pose important environmental and agronomic concerns. Manure injection can conserve nitrogen (N) by decreasing ammonia volatilization. However, the injection band also creates conditions, which potentially favor nitrous oxide production: an abundant organic substrate promoting microbial activity; anaerobic conditions favoring denitrification; large local concentrations of nitrogen. We sought to assess differences in ammonia volatilization and nitrous oxide emissions with conventional, broadcast application and shallow disk injection of dairy slurry over successive growing seasons from 2011 to 2013. Results point to 92-98 percent reduction in ammonia volatilization (for the initial sampling) with injection compared with broadcasting manure, but also reveal 84 to 152 percent greater cumulative nitrous oxide emissions. Although losses of N via nitrous oxide emission were at least 3 orders of magnitude lower than ammonia volatilization, their potential role as a greenhouse gas is of concern.