TPAC Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in West Lafayette, Indiana
Recent efforts have attempted to establish emission estimates for greenhouse gases (GHG) from agricultural soils in the United States. This research project was conducted to assess the influence of cropping system management on non-carbon dioxide (non-CO2) GHG emissions from an eastern cornbelt alfisol. Corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation plots were established, as were plots in continuous management of native grasses or Sorghum/Sudan grass. GHG fluxes were monitored throughout each growing season from 2004 through 2007. Fluxes of N2O were significantly correlated with soil temperature (P < 0.001), and thus a Q10 correction was made (3.48 for N2O). Nitrous oxide emissions from corn were lowest from the precision tillage treatment (2.4 kg N ha-1 yr-1), significantly lower than the conventional tillage (4.9 kg N ha-1 yr-1) or cover crop corn treatments (5.0 kg N ha-1 yr-1). Corn-soybean and biomass-based cropping systems resulted in significantly greater N2O emissions than native grasses. There was a positive correlation between N fertilization rate and N2O emissions when comparing all treatments in this study. These soils were typically a sink for atmospheric CH4 for these cropping systems, and thus N2O is the primary non-CO2 GHG of concern. When evaluating the entire cropping system, native grasses resulted in the lowest N2O emissions, while corn-soybean rotation planted with precision tillage resulted in similar N2O emissions as bare soil and were significantly lower than emissions from the other cropping systems assessed.