Corn Stover Availability
Corn stover and grain production levels are directly tied to each other. The more grain produced, the more stover produced. A harvest index of 50 percent is often used to estimate the amount of stover produced based on grain yield. The harvest index says that of the total aboveground growth of the corn plant 50 percent, by dry weight, would be grain and 50 percent would be stover.
The average corn yield for Iowa was 168 bushel per acre from 2003 to 2012. Using this grain yield, it is estimated that there would be 4.0 tons per acre of corn stover produced. Likewise, a 200 bushel per acre corn crop would produce 4.75 tons per acre of stover. Thus, varying corn grain yields will result in varying corn stover amounts available for harvest in different crop years. The amount of stover that can be removed is a factor of how much stover is produced, the soil erosion potential, and the tillage system used.
Soil Health Implications
Soil health is an important component that needs to be maintained to ensure high productivity. Degradation of soil health over time can limit the productivity of the field. Soil health is determined by several factors, including soil organic matter, soil compaction, soil structure, water infiltration, and water and wind erosion.
Removal of too much corn stover can decrease soil organic matter. Additional traffic from harvesting operations leads to soil compaction, especially if field conditions are wet. Removal of too much stover ultimately can lead to water and wind erosion. To keep the practice of stover harvest sustainable, it is critical to carefully evaluate each field and determine how much stover must be retained to minimize the impact of these constraints.
Publications PM 3052A - Managing Crop Residue Removal and Soil Quality Changes and PM 3052B - Managing Crop Residue Removal and Soil Organic Matter discuss in further detail various soil health aspects including soil aggregation, bulk density, and soil organic matter.
Publication PM 3052D - Consider the Possibility of Reduced Tillage after Biomass Harvest describes different tillage factors that should be considered with residue removal.