Nitrogen cycling trade-offs with broadcasting and injecting dairy manure

Authors: Duncan, Emily; Kleinman, Peter; BEEGLE, DOUGLAS - Pennsylvania State University; Dell, Curtis

Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2019
Publication Date: 3/21/2019
Citation: Duncan, E.W., Kleinman, P.J., Beegle, D., Dell, C.J. 2019. Nitrogen cycling trade-offs with broadcasting and injecting dairy manure. Nutrient Cycling in Agroecosystems. 114(1):57-20. https://doi.org/10.1007/s10705-019-09975-2.
DOI: https://doi.org/10.1007/s10705-019-09975-2

Interpretive Summary: Improving nutrient management in the Chesapeake Bay watershed is imperative to decreasing N loss from agricultural fields. We assessed the fate of N under injection and broadcast treatments on field lysimeters. Fate of N was measured in crop uptake, surface runoff and subsurface flow, and in gas emissions. Despite our inability to close the N balance under each of these systems we were able to conclude that there is an increase in N uptake in corn planted with injected manure as compared to corn planted with broadcast manure. Additionally injected manure offers the potential to decrease the need for additional fertilizer application during the corn growing season.

Technical Abstract: Understanding the fate of nutrients in land-applied manure is key to improving the efficiency of their use in crop production. We developed nitrogen (N) budgets for two years of continuously cropped corn fertilized by dairy manure via broadcast application or shallow disk injection. Major pathways and pools of N loss were monitored on 12, 0.04 ha field lysimeters in central Pennsylvania to estimate the impact of manure application method on N fate: gas emissions; off-site runoff (overland and subsurface flow); crop uptake; and, soil storage. The budgets illuminated trade-offs in N cycling with each management strategy. Crop removal accounted for the largest portions of manure N applied in both budgets (16-43%). Broadcast manure N balances were more difficult to close, and included a large proportion of ‘unaccounted’ N (36% and 58% of applied N for two accounting periods). Even so, results point to cumulative differences in nutrient use efficiencies that can be attributed to the greater conservation of ammonia-N with manure injection. There was an apparent build-up of soil N with manure injection that was not observed with broadcast application (in PSNT measurements). However, these trends were preliminary; over the two growing seasons covered by this study, these differences did not result in significant differences in corn yield or crop N removal.