Brookings, S.D. - Many producers have already turned cattle out on corn stalks and for good reasons, says Nathan Mueller, SDSU Extension Agronomist.
"Fall-winter grazing of corn stalks for 30 to 45 days helps extend the grazing season and reduce winter feed costs, and grazing cattle only utilize about 20 percent of the residue," said Mueller, referencing research compiled by SDSU faculty. "Therefore, no-till and reduced tillage systems still maintain ample residue cover to help reduce soil erosion."
Mueller says the perceived negative effect on crop yields is that grazing cattle on crop residue leads to soil compaction and nutrient removal.
"Grazing does not appear to be a real problem across an entire field," Mueller said.
He adds that average stocking rates of 1.5 Animal Unit Months (one acre for a 1,200-lb cow for 44 days) are being assumed in this discussion.
"A 15-year study at the University of Nebraska has shown that fall grazing of corn stalks does not decrease yield in the following soybean or corn crop (Table 1). Likewise, no-till research at Iowa State University found no significant difference in soybean yields between grazed and ungrazed corn stalks (Table 1)," Mueller said.
Table 1. Crop yield following fall-winter grazing of corn stalks
One measure of compaction, bulk density, taken during the Iowa State study showed no difference between grazed and ungrazed plots. However, another measure called penetration resistance was higher at the Chariton, Iowa site with grazing.
"It is likely that concentrated traffic near water and mineral sources are expected to have some negative effect on soil physical properties and yield," he said. "However, across an entire field, research shows yield of the following crop are not reduced by grazing corn stalks in the fall-winter months."