Scientists and growers have amassed plenty of evidence on the benefits of retaining corn residue, but recent research at the University of Minnesota (UMN) suggests there are circumstances where residue removal delivers agronomic benefits.

“The data we see indicate that residue removal may serve a viable agronomic advantage to the plant,” says Aaron Sindelar, UMN research fellow, of his work on corn’s response to residue removal and nitrogen (N) fertilization. 

Sindelar’s research looks at crop performance on heavy-textured, poorly drained southern Minnesota soils. By each measure – leaf height at the eight-leaf collar stage, grain yield, biomass yield and grain N content – his test fields performed better when residue was removed.

That generally held true regardless of the amount of N applied. 

Sindelar and his university co-researchers, agronomists Jeff Coulter, John Lamb and Jeff Vetsch, also determined that residue removal produced better plant emergence regardless of tillage method.

Retaining residues on the field can help preserve moisture and improve yields in where soil moisture can be a major limiting factor, he explains. 

“For our (Minnesota) producers, soil temperature is often an issue under continuous corn due to the high amount of residue remaining in the field. When residue is removed, it allows the soil to warm faster, which stimulates emergence and early season growth,” Sindelar says.

However, the research only looks at short-term consequences of reducing crop residues. “We’re concerned that the long-term removal could reduce soil carbon levels and lead to a soil productivity decrease,” he says.

If you harvest residue, consider applying manure in order to offset the carbon you remove through the residue, and consider reducing or eliminating tillage in order to reduce further carbon loss, he advises.

Sindelar plans one more year of field trials to produce three years of final data from two locations.  His findings to date show:

  • Leaf length at the eight-leaf collar stage (about four to six weeks into the growing season) was about 8 in. greater in plots where residue was removed.
  • Corn yields were improved in the no-residue plots by about 27 bu./acre at all six levels of N fertilization.
  • Biomass yields were higher in fields without residue, although the increase was not as great when more N was applied.
  • Nitrogen levels were higher in grain harvested in the plots where residue was removed. Nitrogen levels in the grain indicate the overall quality of the grain.