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Title: Crop and soil responses to using corn stover as a bioenergy feedstock: Observations from the Northern US Corn Belt

Author
item Johnson, Jane
item Acosta-Martinez, Veronica
item Cambardella, Cynthia
item Barbour, Nancy

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2013
Publication Date: 2/6/2013
Citation: Johnson, J.M., Acosta Martinez, V., Cambardella, C.A., Barbour, N.W. 2013. Crop and soil responses to using corn stover as a bioenergy feedstock: Observations from the Northern US Corn Belt. Agriculture. 3:72-89.

Interpretive Summary: Corn stover is the material including leaves, stalk and cobs that remain after corn grain is harvested. Corn stover is expected to be used as major non-food, bioenergy feedstock especially in the Northern Corn Belt. Corn stover can be used to produce ethanol, or as a substitute for coal or other fossil fuels. However, enough stover still needs to be returned for soil cover and to build new soil organic matter. When corn stover or other crop residue covers the soil, it reduces soil erosion. Soil organic matter gives soil a dark, rich color. Many soil characteristics are related to how much soil organic matter they contain. There are multiple agronomic and environmental advantages to increasing or at least maintaining soil organic matter. Particulate organic matter is used to gauge how soil organic matter maybe being altered by management practices. There are also soil biology tools that we used to gauge how well the soil can provide nutrient to plants. Information is needed to determine how much corn stover needs to be return to the field to avoid a loss in crop yield during the first several years after harvesting this material. It is also important to look at soil properties that could indicate the ability of soils to support high crop yields. The study suggests that at least on the high quality soils of the Northern Corn Belt some stover may be harvested without reducing crop yield in the first few years following stover removal. The results show that when excessive stover is harvested, the long-term yield potential of the soil may be decreased. This information provides guidance to the bioenergy industry, producers and the general public including policy-makers of the benefits and risks associated with plant-based energy. Short-term harvest of corn stover had limited impacts on subsequent crop yields. However, although not detected within the first years, overharvesting the stover could damage the soil, compromising the ability of those soils to provide food, feed, fiber and fuel for the world.

Technical Abstract: A sustainable bioenergy depends upon soil resources to sustain and increase crop production. This study examined soil (erosion, soil C, and microbial indicators) and crop response to stover removal treatments [Full Residue Returned (FullRR), Moderate Residue Returned (ModRR) and Low Residue Returned (LowRR)] in a chisel field (Chisel) and two fields managed without tillage (NT1995 and NT2005). Every year, all fields were planted to corn (Zea mays L.) and soybean (Glycine max [Merr.]). All stover was returned (FullRR), or half the rows (ModRR), or all rows (ModRR) were harvested with a forage harvester (2005-2008). From 2009-2011 stover was harvested with a one-pass combine set just below the ear (ModRR) or to cut near the soil surface (LowRR). At planting, the chisel field only had 20% residue covered soil, while NT1995 and NT2005 fields had 45% residue covered soil. A shift in dry-sieved aggregates toward more <0.5 mm and fewer >2 mm sized aggregates, suggests stover harvest increased susceptibility to erosive forces. One year of stover harvest had minimal impact on soil microbial indicators. In the NT1995 field, particulate organic matter (POM) content decreased 21% in the LowRR compared to FullRR treatment. Harvesting corn stover did not measurably alter corn or soybean yield, except in the NT1995 field, where the six-year-average soybean yield was reduced by the LowRR treatment (2.88 Mg ha-1) compared to FullRR and ModRR treatments (3.14 Mg ha-1). Dry aggregates and residue cover were more sensitive to stover harvest than crop yield, POM or soil microbial indicators.