Pricing drought-stressed corn silage/stover
By Noel Mues
UNL Extension Educator
A long-standing rule of thumb was that a ton of normal corn silage at 65 percent moisture that has been ensiled is worth 10 times the price of a bushel of shelled corn. This relationship may not be as valid now as it was, due to the demand for corn to produce ethanol. The following pricing methods might estimate the value of drought-stressed silage more closely when compared to alternative forage-based feed sources.
First method: Establish a minimum price as the basis to negotiate a final price. The National Corn Handbook states, "At the minimum, each ton of silage is worth about five times the current price per bushel of shelled corn plus $2 per ton to cover the added cost of harvesting and storing corn silage rather than grain." For example, if shelled corn is selling for $6 per bushel, the minimum price for drought-stressed silage would be $6 per bushel x 5 = $30 plus $2 = $32 per ton.
(Harvest costs have been adjusted, based on 2008 Machinery Cost Estimates, published by the University of Minnesota. Assumptions: Forage yield = 10 tons per acre, Ensiling shrink = 10 percent.)
Second method: Compare to alfalfa hay. Perhaps the most direct method of pricing drought-stressed corn silage as a feed is to compare it with other forage sources. The National Corn Handbook states "One ton of 30 percent dry matter corn silage will substitute for about one-third of a ton of 85 percent dry matter alfalfa hay and would be priced accordingly." For example, if alfalfa hay is selling for $100 per ton, a ton of normal corn silage would be priced at $33 per ton and drought-stressed silage would be priced at $33 x 90 percent = $30 per ton.
Pricing dry corn stover: Dry stover made from drought-stressed corn can be compared to drought-stressed corn silage as an alternate feed source. If the two products have the same nutrient content on a dry matter basis, the price of dry forage might be based on the price of drought-stressed corn silage, corrected for differences in waste.
A ton of 70 percent moisture (30 percent dry matter) silage contains 2000 x 0.30 = 600 pounds of dry matter. A ton of 20 percent moisture (80 percent dry matter) dry corn stover contains 2,000 x 0.80 = 1,600 pounds of dry matter. However, unless the corn stover is put through a grinder to reduce particle size, animals will sort, eating the leaves, ears, and small stems but leaving the coarser stems. If we assume there will be 20 percent more waste when feeding dry corn stover as compared to feeding silage, the useful dry matter in a ton of stover would be 1,280 pounds. By this reckoning, a ton of dry corn stover would contain 1,280 / 600 = 2.13 times as much useful dry matter per ton than corn silage. If drought damaged silage is selling for $30 per ton, dry drought-stressed corn stover with the same nutrient content might be expected to sell for about $30 x 2.13 = $64 per ton.
The local market value of any forage made from drought-stressed corn will depend on the availability of alternative feed sources, the nitrate content of the stover, and the transportation costs compared to alternative feed sources.
For more information see G1865 "The Use and Pricing of Drought-Stressed Corn" at http://www.ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=1048.