Submitted to: USDA Greenhouse Gas Symposium
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 2006
Publication Date: February 8, 2007
Citation: Djurickovic, M., Cavigelli, M.A., Mccarty, G.W. 2007. Carbon dioxide and nitrous oxide fluxes in organic, no-till and chisel-till cropping systems [abstract]. USDA Greenhouse Gas Symposium. Technical Abstract: Organic cropping systems may have the potential to increase soil C sequestration and reduce soil nitrous oxide (N2O) fluxes compared to conventional systems but organic systems are not well studied. We are measuring greenhouse gas fluxes and soil C sequestration in no-till, chisel-till and organic cropping systems at the USDA-ARS Beltsville Farming Systems Project, a long-term cropping systems project. Here, we present greenhouse gas flux data collected from the corn phase of three corn-soybean-wheat/legume crop rotations. We measured fluxes on 24, 27, and 26 dates in three field replicates in 2004, 2005, and 2006, respectively. Seasonal gas flux patterns and cumulative annual fluxes vary by year, apparently reflecting differences in weather, especially rainfall patterns. For example, there were no differences in cumulative CO2 flux among systems in 2006, a year with prolonged dry periods. In 2004, however, cumulative CO2 flux was greater in the organic (12.88 g CO2 m-1 h-1) than in the no-till (8.62 g CO2 m-1 h-1) and chisel-till (10.38 g CO2 m-1 h-1) systems. Differences among systems were due mostly to large CO2 fluxes in spring in the organic system, especially following moldboard plow incorporation of a hairy vetch cover crop and disk incorporation of poultry litter. The largest N2O fluxes in both years occurred after N fertilization in the no-till and chisel-till systems and after green manure plowdown in the organic system. While there were no differences among systems in cumulative N2O flux in 2005, cumulative N2O flux in 2006 (through August) was greatest in no-till plots (2.5 ug N2O-N m-2 h-1), lowest in organic plots (0.6 ug N2O-N m-2 h-1) and intermediate in chisel-till plots (1.9 ug N2O-N m-2 h-1). A full assessment of cropping system impacts on greenhouse gas fluxes will have to consider interannual variability and will likely require long-term monitoring.