As wheat harvest continues, the question always comes up regarding the value of wheat straw sold out of the field. From a pure fertilizer standpoint, wheat straw contains very little in terms of phosphorus (P2O5), but moderate amounts of nitrogen (N) and potassium (K2O). According to the Michigan State University Extension Bulletin E-2904, “Nutrient Recommendations for Field Crops in Michigan,” the actual amounts of N, P2O5 and K2O contained in a ton of wheat straw are 13, 3.3 and 23 pounds, respectively. Actual nutrient content can vary based upon environmental conditions during the growing season and after the grain is harvested as well as soil nutrient supply, so if one really wants to know the actual value, straw analysis can be conducted by any lab that processes plant samples.
How much is that straw worth from a nutrient perspective? The answer depends upon the current market value of nutrients that would be removed in the straw. Using today’s prices, a pound of N, P2O5 and K2O costs $0.57, $0.50, $0.40, respectively. Thus, a ton of straw will contain $18.33 worth of nutrients. Again, this number can be variable based on the type of fertilizer and prices, but it gives you a starting point for your own economic analysis.
It’s always best if prices are determined on a “per ton” basis rather than “per acre” basis. This takes the guess work out of determining actual yield. The yield of wheat straw can vary greatly from 1 to 3 tons per acre. Straw yield is related to the height that the stubble is cut and the stand of wheat generally reflects the grain yield.
The seller has to determine how much profit over the cost of fertilizer is reasonable and put a value on the organic material that is leaving their farm. Farmers should consider planting cover crops or applying manure to replace this organic material. Often livestock farms are willing to trade manure for straw which can help the seller maintain the field’s nutrient and organic matter levels if straw is harvested. The buyer must consider the harvest costs which vary based on harvest method.
It is always important for the buyer and seller to be clear and have agreed on the following three issues: the price, how the harvested tons will be determined, and when the buyer will make full payment for the straw being harvested.
Source: Michigan State University Extension
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