Either way, remember to account for the plant nutrient value.
As wheat harvest gets underway this week, balers are running closely behind the combine to get the straw baled and soybeans planted. Since we are already a week behind normal, and up to two weeks behind recent years, the rush is on. Along with the straw a significant amount of nutrients are being removed from the field. Information from the Penn State Agronomy Guide indicates a wheat crop with the straw removed will typically remove 1.0 pound of P2O5 and 1.8 pounds of K2O per bushel of grain yield. A typical yield of 60 bushels (grain and straw) will remove 60 pounds of P2O5 and 110 pounds of K2O. In a high yielding situation of 100 bushel wheat, 100 pounds of P2O5 and 180 pounds of K2O will be removed.
Ohio State Extension did analysis of wheat straw to determine if their “book values" were still accurate. What they found was that their book values are still within the range that they have been previously stating. With that being said, if wheat straw is spread and not baled, each ton will return 11 pounds of N, 3 pounds of P2O5, and 20 pounds of K2O. The nitrogen will not be immediately available for uptake, the P2O5 is not too significant, but the K2O certainly is. If two tons of straw is left on the field, 40 pounds of K2O is returned. At $0.45 per pound of K2O, that is $18 per acre plus the organic value of the carbon going back on the field.
Another way to recover some of the K2O from the straw is to spread the straw out the back of the combine, allow it to rain on it and leach some of the K2O from the straw into the soil, then rake it up and bale it. Is that worth recovering some of the $9 per ton of K2O? Probably not. If you are planning to sell your straw, you will likely take a larger loss on the price per ton you receive, compared to the other farmer with bright yellow straw.
The take home message is whether you bale your straw or not, make sure you have enough K2O for the next crop. As Extension Educators across the state have reported, it is not too uncommon to see K2O deficiencies in corn and soybeans.
Source : psu.edu