It's time to determine what to do with corn stover, said Fabian Fernandez, University of Illinois Extension soil and plant fertility specialist.

"As a new growing season comes to an end, growers are considering their options to determine what to do with corn stover," he said. "Corn stover has become more of a management concern over the years as new hybrids produce stronger stalks, relatively larger amounts of biomass, more corn-on-corn acres are planted, and less tillage is done."

Stronger stalks are a desirable trait to help with standability of the crop, he said. But the drawback is that these materials are more difficult to break down in time for the following growing season.

Stalks, along with other crop residues, can interfere with planting in the spring. Large amounts of crop residue left on the soil surface can also delay planting or seed emergence by keeping soils cool and wet longer into the spring.

Fernandez said a practice that is increasingly being promoted is applying nitrogen, typically urea-ammonium nitrate (UAN) or ammonium sulfate (AMS), to increase microbial activity and induce residue decomposition.

"Microbial decomposition of corn stover is typically slow because the material has a high C:N ratio," Fernandez said. "The basic concept behind application of N to the residue is that by applying N, it is possible to reduce the C:N ratio and allow microbes to act on, or start eating, the material quicker."

While this concept makes sense, Fernandez said research conducted at the University of Wisconsin showed no benefit for fall application of nitrogen to increase microbial decomposition of corn residue. They observed that applying N did not change the C:N ratio.

"I suspect there was no change in the C:N ratio because nitrogen can easily be washed off from the residue with rain," he said.