|Moorman, Thomas - Tom|
Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2009
Publication Date: 11/23/2009
Citation: Jarecki, M.K., Parkin, T.B., Chan, A.S., Kaspar, T.C., Moorman, T.B., Singer, J.W., Kerr, B.J., Hatfield, J.L., Jones, R. 2009. Cover Crop Effects on Nitrous Oxide Emission from a Manure-Treated Mollisol. Agriculture, Ecosystems and Environment. 134(1-2):29-35.
Interpretive Summary: Nitrous oxide is a greenhouse gas that is approximately 300 times stronger than carbon dioxide. Agriculture contributes 40% to 60% of the total annual nitrous oxide emissions to the atmosphere. Development of management practices to reduce these emissions would have a significant impact on greenhouse gas levels. One potential management practice is the use of winter cover crops to scavage excess soil nitrogen when the main crop is not present. In laboratory experiments we observed that a rye grass crop reduced soil nitrate levels and also nitrous oxide emissions. In field experiments, the presence of a grass cover crop did not influence nitrous oxide emissions, rather it was nitrogen application rate that had the major influence on the magnitude of nitrous oxide emissions. These findings should be useful to land managers and scientists interested in developing strategies to reduce greenhouse gas emissions to the atmosphere.
Technical Abstract: Agriculture contributes 40% to 60% of the total annual N2O emissions to the atmosphere. Development of management practices to reduce these emissions would have a significant impact on greenhouse gas levels. Non-leguminous cover crops are efficient scavengers of residual soil NO3, thereby reducing leaching losses. However, the effect of a grass cover crop on N2O emissions from soil receiving liquid swine manure has not been evaluated. This study investigated: i) the temporal patterns of N2O emissions following addition of swine manure slurry in a laboratory setting under fluctuating soil moisture regimes, ii) assessed the potential of a rye (Secale cereale L.) cover crop to decrease N2O emissions under these conditions, and iii) quantified field N2O emissions in response to either spring applied urea ammonium nitrate (UAN) or different rates of fall-applied liquid swine manure, in the presence or absence of a rye/oat winter cover crop. In laboratory experiments we observed a significant reduction in N2O emissions in the presence of the rye cover crop. Field experiments were performed on a fine-loamy soil in Central Iowa from October 12, 2005, to October 2, 2006. Nitrous oxide emissions were evaluated at three swine manure application rates and with spring applied UAN, in the presence or absence of an oat/rye cover crop. We observed no significant effect of the cover crop on cumulative N2O emissions in the field. The primary factor influencing N2O emission was N application rate, regardless of form or timing. The response of N2O emission to N additions was non-linear, with progressively more N2O emitted with increasing N application. These results indicate that while cover crops have the potential to reduce N2O emissions, N application rate may be the overriding factor.