Corn (Zea mays L.) residue is being considered as a feedstock for biofuels production. The impact of removing corn residue on soil productivity is not well understood. A corn-soybean [Glycine max (L.) Merr.] rotation was established in 2000 to determine the effect of removing corn residue at three rates (37, 55, and 98%) on soil organic carbon (SOC) in the 0- to 5-cm layer of soil after 8 yr. The effect of cover crops {slender wheatgrass [Agropyron caninum (L.) Beauv.] in corn and lentil (Lens culinaris Medik. variety Morton) in soybeans} on SOC was also measured. As the rate of residue removal increased, soil organic matter (SOM), wet aggregate stability (WAS), C/N, and microbial activity decreased significantly. Although the effect was not significant, there was a decrease in SOC as the rate of removal increased. At the high residue removal rate, SOM analyzed by quantitative C-13 NMR contained an abundance of aromatic C structures, suggesting that less humified pools of soil C are not being replenished. The humin fraction of the soil had a reduction in SOC under the medium and high rates of residue removal without a cover crop and is likely beginning to be depleted. Bradford-reactive soil protein and immunoreactive soil protein were higher in soils with cover crops, likely due to increased plant diversity and extending the growing season to allocate more C belowground. Overall, the data suggest that the soil properties indicative of soil quality are negatively impacted by removal of corn residue.

Publication Information
Sarah J. Stetson
Shannon L. Osborne
Thomas E. Schumacher
Anna Eynard
Gabriela Chilom
James Rice
Kristine A Nichols
Joseph L. Pikul Jr
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