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The impact of corn stover removal on N2O emission and soil respiration: An investigation with automated chambers

Baker, John M., Fassbinder, Joel, Lamb, John A.
BioEnergy research 2014 v.7 no.2 pp. 503
USDA, bioenergy, carbon, carbon dioxide, corn, corn stover, nitrous oxide, planting, silage, soil, soil respiration, soil sampling, spring, Minnesota
Corn stover removal, whether for silage, bedding, or bioenergy production, could have a variety of environmental consequences through its effect on soil processes, particularly N2O production and soil respiration. Because these effects may be episodic in nature, weekly snapshots with static chambers may not provide an accurate picture. We adapted commercially available automated soil respiration chambers by incorporating a portable N2O analyzer, allowing us to measure both CO2 and N2O fluxes on an hourly basis through the growing season in a corn field in southern Minnesota from spring 2010 through spring 2012. This site was part of a USDA-ARS multi-location research project for five growing seasons, 2008-2012, with three levels of stover removal: zero, full, and intermediate. Initially in spring 2010, two chambers were placed in each of the treatments, but following planting in 2011, the configuration was changed, with four chambers installed on zero removal plots and four on full removal plots. The cumulative data revealed no significant difference in N2O emission as a function of stover removal. CO2 loss from the full removal plots was slightly lower than from the zero removal plots, but the difference between treatments was much smaller than the amount of C removed in the residue, implying loss of soil carbon from the full removal plots. This is consistent with soil sampling data, which showed that in 5 of 6 sampled blocks the SOC change in the full removal treatments was negative, relative to the zero removal plots. We conclude that a) full stover removal may have little impact on N2O production, and b) while it will reduce soil CO2 production, the reduction will not be commensurate with the decrease in fresh carbon inputs, and thus will result in SOC loss.