Harvest Less Corn Residue to Maintain Soil Productivity

October 21, 2008

Increasing demand for harvested crop residue has left many producers wondering whether they should bale and sell their crop residue or leave it in the field. Before making that decision producers should consider how the removal of crop residue may impact their soil’s productivity and their bottom line, according to an agronomist with the Natural Resources Conservation Service (NRCS).

Barb Stewart, conservation agronomist with NRCS in Des Moines, Iowa, reminds farmers that plant residue left in the field after harvest can serve as a valuable resource.

“The residue left on the field following harvest is frequently referred to as ‘trash’.  But crop residue contains some valuable nutrients,” Stewart said. 

Based on data from Iowa State University, a ton of corn residue contains about 37 lbs. of nitrogen, 3.5 lbs. of phosphorous, 33 lbs. of potassium, 21 lbs. of calcium and 17 lbs. of magnesium. Using fertilizer prices from this spring, the estimated cost of nutrients removed would be about $22/acre or $10/ton of residue removal.

Stewart said, “The nutrients found in crop residue help increase soil organic matter. Soil organic matter contributes directly to the nutrient availability and the nutrient and water holding capacity of the soil. The greater the soil organic matter, the healthier the soil.  Organic matter provides carbon and energy for soil microorganisms which are critical for nutrient cycling in the soil. And residue is needed for healthy soil microorganisms,” she said 

These microorganisms help to hold the nutrients in the soil and in some cases move the nutrients to the plant. We are learning so much about how important soil organisms are to good crop growth, she said.

Studies show that removing more crop residue than what the soil can tolerate will eventually result in a decline in soil health and yield. Research by the USDA-Agriculture Research Service at the University of Nebraska Agriculture Research and Development Center found that continuous no-till corn yields decreased an average of 6 percent over five years when half of the crop residue was removed each year.  

Crop residue also provides ground cover, which helps control soil erosion. Many producers choose to maintain certain levels of residue cover to control soil erosion. Producers with highly erodible fields should contact their local NRCS office to review their conservation plan and discuss the potential impact of harvesting crop residue before they remove any from the field.

The actual cost of harvesting and bailing the residue should also be considered. Based on a custom baling price of $11.80 per big round bale, the cost of harvesting the residue can range from $60 to $70 per acre, depending on how many bales there are per acre.  If the average bale weighs 1,200 lbs. that equals about $20/ton.

Stewart wants producers thinking about harvesting crop residue to know they have many ways to reduce the impact of removing crop residue. 

“Switching to a no-till system will help offset the impact of harvesting residue by reducing soil disturbance and increasing soil health.  Producers who reduce the number of years low-residue producing crops are grown (e.g. soybeans) can somewhat offset the negative impact of removing crop residue,” she said.

She added that establishing a cover crop prior to harvest or right after harvest can minimize the impacts of crop residue removal.  Cover crops protect the soil surface, enhance soil biology, capture remaining nutrients and if legumes are planted, add nitrogen back into the soil.

“Adding manure into the soil is another option for reducing the impact of harvesting crop residue. Manure will not only replace some of the nutrients that were removed with the crop residue, but will also add some organic matter back into the system,” Stewart said.

For more information about the impact of harvesting crop residue visit your local NRCS office located in the USDA Service Center. 

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Contact:
Barb Stewart, NRCS Agronomist
Phone: 515-323-2260

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