Greenhouse Gas Emissions from Soils in Corn-Based Cropping Systems.

Crop rotation is a management practice with high greenhouse gas (GHG) mitigating potential that is often neglected due to economic influences. Three long-term rotation studies in Wisconsin were selected to assess potential opportunities for mitigating GHG emissions by comparing temporal and spatial variability of N2 O, CO2, and CH4 emissions in continuous corn (Zea mays L.) (CC), corn-soybean [Glycine max (L.) Merr.] (CS), and corn-soybean-wheat (Triticum aestivum L.) (CSW) using a static chamber method. Greenhouse gas emissions were influenced by weather conditions and following nitrogen (N) application during a 3-year measurement period. In high N input environments at Arlington and Lancaster, N2 O emissions in CC were 5.80 and 4.40 kg N ha-1 , respectively, which was much higher than the emissions in CS and CSW rotations that ranged from 1.52 to 3.33 kg N ha-1 . In the low N input environment at Marshfield, N2 O emissions were not statistically different among CC, CS, and CSW rotations (1.20 to 1.66 kg N ha-1 ). Yield-scaled N2 O emissions were not different among crop rotations. When pooled over locations, CO2 emissions were highest in CC (4.16 Mg C ha-1 ) and were similar in CS and CSW (3.71 and 3.50 Mg C ha-1 , respectively). Soils either emitted or absorbed small and inconsistent amounts of CH4 . These results provide important insights as to how weather conditions and differences among management practices affect GHG emissions and show that application of either 2-yr CS or 3-yr CSW rotation can be equally effective in reducing N2 O emissions compared to CC, especially with high N applications. This article is protected by copyright. All rights reserved.