Growers ask if they can speed decomposition of corn residues by applying nitrogen fertilizers. Research conducted by Iowa State examined the rate of decomposition by applying different rates (0, 30, 60 lb. N/acre) of nitrogen fertilizers to corn crop residues. They measured the rate of decomposition and found addition of nitrogen fertilizer did not increase the rate of corn stalk decomposition in a three-year study.

Also, growers question whether Bt and non-Bt corn hybrid residues break down at different rates. Three years of work using three different types of tillage systems: deep tillage, strip tillage and no-till did not show any differences between Bt and non-Bt corn hybrid residue decomposition.

There are three primary drivers of corn stalk decomposition.  The contact of the corn residue with the soil surface, temperature, and soil moisture. These conditions interact at the surface of the soil to bring about decomposition by soil microbes.

Soil microbes need an adequate pH, oxygen, good moisture, and temperatures above 50 degrees F. to function and decompose crop residues.

For more information, contact Wayne Flanary, Field Specialist in Agronomy, University of Missouri Extension at 816-279-1691.