Cycles-simulated nitrous oxide emissions from dairy slurry manure fertilizer applications to corn

Open Access
- Author:
- Chou, Jessica
- Area of Honors:
- Environmental Resource Management
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Heather D Karsten, Thesis Supervisor
Robert David Shannon, Thesis Honors Advisor - Keywords:
- nitrous oxide
greenhouse gas emissions
dairy cropping system
manure
corn
drawdown - Abstract:
- This thesis explored modelling nitrous oxide emissions (N2O) in dairy cropping systems and calculating N2O emissions from different dairy slurry manure fertilizer management strategies. A portion of animal manure and inorganic urea ammonium nitrate (UAN) fertilizer applied to farmland as fertilizer can emit the greenhouse gas, nitrous oxide, which has a warming potential 298 times greater than carbon dioxide (IPCC, 2006). Potential opportunities to reduce nitrogen losses to the environment are improving the application timing, placement, and rate of fertilizers. In northeastern U.S., livestock manure is typically applied prior to corn planting in spring, making manure nutrients vulnerable to environmental losses. Recent innovations in manure application technology allow for manure application in early stages of corn growth. Research focused on this improved synchronization of manure fertilizer application with crop uptake to reduce N2O emissions is limited. In this study, we used measured results from a no-till conservation dairy cropping system in Central Pennsylvania to evaluate how well Cycles, an agro-ecosystem computer model, simulates N2O emissions. We found that Cycles in general accurately simulated emissions from broadcast manure and inorganic liquid urea ammonium nitrate fertilizer applied to corn following soybean. Improvements can be made to fertilizer applied by manure injection and in corn following two years of growing alfalfa and orchard grass. Next, we used Cycles to simulate the N2O emissions from a continuous corn field managed with different fertilizer application scenarios in the same field in Rock Springs, Pennsylvania. We found that splitting manure into two applications (before corn planting and injected side-dress) and lowering total nitrogen input rate by 56 kg N ha-1 reduced average annual total N2O emissions by 17% to 19%. When more of the total manure was applied as side-dress, the cumulative N2O emissions were reduced while still achieving similar corn yields. These results can encourage more manure application technological innovations, financial incentives to promote adoption of side-dressing manure, and discourage manure and nitrogen applications that exceed crop N requirements to reduce N2O emissions and other potential N losses to aquatic ecosystems and to the environment.