Location: Soil and Water Management ResearchTitle: The impact of corn stover removal on N2O emission and soil respiration: An investigation with automated chambers Author
Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2014
Publication Date: 2/4/2014
Publication URL: http://handle.nal.usda.gov/10113/59527
Citation: Baker, J.M., Lamb, J.A., Fassbinder, J. 2014. The impact of corn stover removal on N2O emission and soil respiration: An investigation with automated chambers. BioEnergy Research. 7:503-508. Interpretive Summary: There is increasing demand for the harvest of corn stover (the non-grain portion of the plant) for a variety of uses, including fuel production and animal feed. However, there are a number of environmental concerns raised by the prospect of widespread stover harvest. One issue is its potential impact on the emission of nitrous oxide and carbon dioxide, two of the major greenhouse gases. To investigate this question, we developed an automated chamber system that measured nitrous oxide and carbon dioxide emissions every hour throughout two growing seasons in a field experiment in Minnesota that contained plots where stover was removed each year and plots were it was returned to the soil. Four chambers were placed in each treatment. The data revealed no significant difference in nitrous oxide emission between treatments. They did show a difference in carbon dioxide emission, with greater release from the plots where stover was returned to the soil. However, the difference was much smaller than the difference in carbon that was input to the system, a strong indication that the plots in which stover was removed were losing soil carbon. This conclusion was supported by soil sampling, and suggests that widespread harvest of corn stover will result in loss of soil organic matter, which could have a negative impact on soil productivity.
Technical Abstract: 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.