Corn stover is made up of the stalk, leaves, husks and tassels left in the field after harvesting the grain with a combine. This stover can be used to make advanced biofuels or be used as a low quality, emergency livestock feed. There are a number of factors you should consider before you set a price for corn stover. These include nutrient removal, soil erosion and maintaining soil quality. This article discusses these three issues and how they should influence your decision whether or not to sell corn stover from your farm.
When you remove stover, you are taking nutrients with you. Table 1 shows the nutrient content of corn stover per dry matter ton of stover. The value of these nutrients needs to be calculated into the value of the stover. Since fertilizer prices vary widely through the year and from year-to-year, you might consider developing a simple pricing index. Current prices are listed in Table 1. Over the past five years, they have ranged from $499 to $853 per ton. The price you pay for these nutrients will depend on the time of year you purchase them and the volume of fertilizer you buy. Make sure to use the price you pay – not a national average. Use previous farm records to determine your average cost of nutrients over the past five years and use your own judgment about whether you think prices this year will be higher or lower.
Table 1. Corn stover nutrient removal
* Source: USDA-Illinois Dept. of Ag Market News
Based on these numbers, the value of nutrients removed in the stover is $31.52 per ton. This would be the minimum price you would need to receive in order to break even on the stover. Harvesting, transportation and storage costs are not part of this price.
Soil erosion from wind and water is another important consideration. If too much stover is removed, topsoil can be eroded away from the forces of wind and water. Tillage plays a key role, also. The Revised Universal Soil Loss Equation (RUSLE2) is a tool you can use to determine soil erosion risk from water. It takes into account soil types, rainfall patterns and topography. Every field is different, so the amount of stover you should leave in the field will vary from field-to-field. Your local NRCS staff can help you run the equation or you can download the software.
Preliminary research data fromshows that current equipment used to harvest stover can only pick up about 25 percent, leaving 75 percent in the field. Line-transect evaluations show that this level of stover removal more than satisfies the RUSLE2 needs. However, in fields with long, steep hills you might need to leave all of the stover on that part of the field.