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JenREES 12/5/21

With high fertilizer prices and some short on forage, I’ve received questions on determining a value for corn residue baling for a good month now. I know there are mixed feelings on this topic, particularly because of the range of what fields look like depending on conditions and equipment settings. Our job is to share the research. It is an opportunity for residue management while also helping our livestock sector. The following is a portion of what Ben Beckman, Brad Schick, and I wrote recently for CropWatch and BeefWatch taking a system’s approach to this topic. Additional details of cost considerations can be found at: https://go.unl.edu/3g84.

Price of cornstalk bales via Nebraska/Iowa hay summary released Thursdays are currently going for $60/ton for large rounds ($100/ton ground). For every 40 bu/ac of corn, approximately one ton of residue is produced. Each ton of corn residue contains 17 lb N, 4 lb P2O5, 37 lb K, and 3 lb S. With rising fertilizer prices, residue this fall will contain up to $34 worth of nitrogen, potassium, phosphorus and sulfur per ton (at time or writing this). Do all those nutrients need to be replaced? Not necessarily for each field. With most Nebraska fields at sufficient K levels, we mostly consider replacing the other nutrients.

The nitrogen replacement may also be flexible due to potential increased mineralization that can occur due to the change in C:N ratio with residue removal. At South Central Ag Lab near Clay Center, eight years of residue removal showed increased yields in spite of a net negative nitrogen balance by removing residue (more nitrogen removed with the residue than what was applied for the crop). Thirty-six studies over 239 site-years showed a 3% average yield increase when residue was removed versus not removed, in locations where water was not a limiting factor. The yield increases are hypothesized to be from more even plant stands and/or from increased soil mineralization.

Based on the research, the following are UNL’s recommendations for which fields to consider for corn residue removal:

  • Use reduced tillage (no-till or strip till) on fields where residue is removed.
  • Only harvest corn residue when fields yield over 180 bu/ac.
  • Avoid fields or areas with slopes greater than 5%.
  • Avoid removing more than 2 tons/ac of residue and maintain at least 2.4 tons/ac of residue. Talk with people at equipment companies on how to set the equipment for corn residue baling to avoid so much soil in the bale and to keep at least 50% residue on the surface.
  • In continuous corn, harvest cornstalks every other year. In corn-soybean, harvest cornstalks every four years.
  • Consider applying manure or use a cover crop after baling cornstalks for amelioration.

From a nutritional standpoint, cornstalk bales are typically even lower quality than straw. Even if being selective with what we harvest by only baling the two to three rows behind the combine, we can only count on around 5% crude protein and up to 45% total digestible nutrients (TDN). With these nutritional values, diets will likely need to consist of additional protein, probably in the form of distillers grains.

To find the value, we need to compare a cornstalk/distillers grain diet with what it would be replacing. Dr. William Edwards, Iowa State emeritus ag economist, solved this problem on a worksheet. For his example, the original diet consisted of 2.6-ton alfalfa-brome hay and 0.3 ton dry distillers grain. One-ton cornstalks replaces 1.16-ton of hay and requires an additional 0.22-ton distillers grain.

If mixed hay is going for $150 per ton (as fed) and dry distillers grain at $200 per ton (as fed), the stalk value would be 1.16 x $150 (hay value) minus 0.22 x $200 (distillers grain value), which comes out to $130 per ton. The stalk and cob in corn residue are unpalatable and will not be consumed by cattle unless the bale is ground. Thus, cornstalk bales are usually ground, reducing the value to the end user by $10-15 per ton. In the end, this drops our cornstalk value to $117 per ton. This value can serve as a breakeven price when deciding to purchase corn residue bales to change feed rations versus using a traditional hay ration. The fuller context of this article can be found at: https://go.unl.edu/3g84.

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