Maintain soil organic matter when harvesting corn residue

By Jodi DeJong-Hughes and Jeff Coulter, University of Minnesota Extension

ST. PAUL, Minn. (4/6/2009) — In most fields, corn residue is incorporated into the soil with tillage, or is left on the soil surface. But some livestock producers are harvesting corn residue for feed and bedding.

There is also interest in using corn residue for biofuel production to reduce U.S. reliance on fossil fuels. However, soil organic carbon and ultimately soil productivity will be reduced if all corn residue in a field is regularly harvested and other sources of carbon aren’t returned to the soil.

The amount of corn residue that can be sustainably harvested in the absence of supplemental carbon (manure, sewage sludge, perennials or cover crops) depends on the crop rotation and tillage system. The potential for sustainable harvest of crop residues is much greater when a conservation tillage system is used.

In terms of crop rotation, more root and shoot residue is produced with continuous corn than with the corn-soybean rotation. Residue removal is best suited to continuous corn grown with conservation tillage.

Corn cobs are quickly becoming recognized as an important feedstock for ethanol and gasification plants. They have more consistent density and moisture than corn residue, and collecting cobs allows the remaining residue to be returned to the soil. This allows cob harvest to be a sustainable practice in more cropping systems than residue harvest is.

While it is critical to maximize profitability from the land, we need to balance short-term economics with long-term sustainability. When harvesting corn residue, use common sense and consider these guidelines to maintain soil organic matter levels and protect against erosion:

• Target corn residue harvest in fields that will be planted to corn next year.
• Rotate residue harvest among fields so that residue is not removed from the same field every year.
• Reduce tillage following residue harvest.
• To add carbon back to the soil, use manure instead of or in addition to commercial fertilizer.
• Consider winter cover crops. Roots from winter cover crops are extremely effective at scavenging residual soil nitrate and adding carbon to the soil.

For more detailed information, see www.extension.umn.edu. Click on “agriculture, then “corn” for the new publication titled “Considerations for Corn Residue Harvest in Minnesota.”

Any use of this article must include the byline or following credit line:
Jodi DeJong-Hughes is an educator; Jeff Coulter is an agronomist, both with University of Minnesota Extension.

Media Contact: Catherine Dehdashti, U of M Extension (612) 625-0237, ced@umn.edu

URL: http:// www.extension.umn.edu/extensionnews/2009/maintain-soil-organic.html  This page was updated April 6, 2009 .
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