Response of Soil Surface Greenhouse Gas Fluxes to Crop Residue Removal and Cover Crops under a Corn-Soybean Rotation.

Excessive crop residue returned to the soil hinders farm operations, but residue removal can affect soil quality. In contrast, cover cropping can return additional residue to the soil and improve soils and environmental quality compared with no cover cropping. Residue and cover crop impacts on soil surface greenhouses gas (GHG) emissions are undetermined and site specific. Thus, the present study was conducted to investigate the impacts of corn ( L.) residue management and cover cropping on GHG fluxes. The fluxes were measured from 2013 to 2015 using static chamber under corn and soybean [ (L.) Merr.] rotation initiated in 2000 at Brookings, SD. Treatments included two residue management levels (residue returned [RR] and residue not returned [RNR]) and two cover cropping (cover crops [CC] and no cover crops [NCC]). Results showed that RR under corn and soybean phases significantly reduced cumulative CO fluxes (2681.3 kg ha in corn and 2419.8 kg ha in soybeans) compared with RNR (3331.0 kg ha in corn and 2755.0 kg ha in soybeans) in 2013. The RR emitted significantly less cumulative NO fluxes than RNR from both the phases in 2013 and 2014, but not in 2015. The CC treatment had significantly lower cumulative NO fluxes than the NCC for corn and soybean phases in 2013 and 2014. We conclude that crop residue retention and cover cropping can mitigate the GHG emissions compared with residue removal and no cover cropping.