Nate Bruce, Farm Business Management Specialist, nsbruce@udel.edu
As small grain harvest season ramps up across Delmarva many producers will be considering whether or not to bale straw. Baling straw after harvest is viewed as a way to generate additional revenue with a biproduct of production with the baling cost being the only expense to sell the straw bale, if even applicable. Many producers would be happy to generate an additional $90 – $120 per acre revenue on top of their wheat harvest. However, the nutrients being removed from the field are costs that need to be considered as well when evaluating this additional revenue stream. Wheat straw will remove nitrogen, phosphorus, potassium, and also small amounts of carbon and micronutrients. Baling straw doesn’t necessarily mean the field will be removed completely of nutrients. You can estimate how much you are removing from the soil by evaluating the opportunity cost of nutrients removed in the straw and the price of the nutrients to be applied. Say for example baling 2 tons per acre small grain straw resulted in losing 22 pounds of N, 2.62 pounds of P, and 33.2 pounds of K. The table below shows what the opportunity cost would be in this scenario and how to calculate it.
Evaluating the opportunity cost in this manner doesn’t consider the machinery expense, labor costs, and hauling costs to bale the straw. It also does not account for the machinery expenses and labor costs to apply lost nutrients as well. Fertilizer costs and how they vary considerably from year to year can have an impact on the opportunity cost significantly, impacting the potential financial return of baling small grain straw. For example, the opportunity cost in this example would be vastly different if using 2022 fertilizer prices, which were far higher. Also, the price paid per ton for straw bales can vary as well.
The value of nitrogen, phosphorus, and potash will vary considerably due to location, variety of small grain, efficiency of baler, and soil type. The amount of nutrients removed from the soil in various extension publications on this topic vary considerably for this reason. According to an old Maryland Agronomy News article from July 2016, potash will become plant available quicker than nitrogen and phosphorus because it is not in an organic form. Most producers on Delmarva will plant double crop soybeans where potash will be an important consideration. The article mentioned that as straw deteriorates with rain events and irrigation water, the readily available potash moves into the soil with 60% – 90% of it becoming plant available for the double crop soybeans in 5 to 6 weeks providing about 50% of what the following crop will need. This means potash will be needed in the short run for double crop soybeans if small grain straw is baled and is an expense that needs to be evaluated in this decision as well. It is imperative to also consider the advice of your nutrient management plan when evaluating additional nutrients so that the double crop soybeans can reach their maximum potential. The decision on whether or not to bale small grain straw needs to be evaluated from the short-run financial perspective and long-term soil management perspective. Other factors such as machinery considerations of planting double crop soybeans following the wheat harvest need to be considered as well.
https://agcrops.osu.edu/newsletter/corn-newsletter/nutrient-value-wheat-straw