Main content area

Cover crop effects on nitrous oxide emission from a manure-treated Mollisol

Jarecki, Marek K., Parkin, Timothy B., Chan, Alvarus S.K., Kaspar, Thomas C., Moorman, Thomas B., Singer, Jeremy W., Kerr, Brian J., Hatfield, Jerry L., Jones, Raymond
Agriculture, ecosystems & environment 2009 v.134 no.1-2 pp. 29-35
air pollution, nitrous oxide, gas emissions, greenhouse gases, pollution control, cover crops, Secale cereale, rye, Avena sativa, oats, soil amendments, pig manure, application rate, application timing, Mollisols, leaching, nitrogen fertilizers, urea ammonium nitrate, good agricultural practices, crop production, Iowa
Agriculture contributes 40-60% 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. Laboratory experiments investigating cover crop effects N₂O emissions were performed in a controlled environment chamber programmed for a 14h light period, 18°C day temperature, and 15°C night temperature. Treatments with or without a living rye cover crop were treated with either: (i) no manure; (ii) a phosphorus-based manure application rate (low manure): or (iii) a nitrogen-based manure application rate (high manure). 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. 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.