Wheat harvest is progressing through Ontario, whether or not your farms have been deluged with rains or suffering from drought. One thing that is constant with the wheat harvest is deciding whether or not to sell the straw from the field.
What you need to know to reach a decision on whether or not to sell:
- Nutrient concentration in straw varies greatly from variety to variety and year to year
- K is leached from straw through rainfall after maturity and can vary as much as 500%
- N Necessary for micro-organisms to break down straw may be removed
Using average nutrient values for straw, we can calculate replacement of soil nutrients (based on 2.5 tonne/ac straw yield)
- N – 14.0 lbs/tonne; equivalent to 76 lbs/ac Urea
- P – 3.7 lbs/tonne; equivalent to 18 lbs/ac MAP
- K – 26.5 lbs/tonne; equivalent to 110 lbs/ac Potash
With volatile fertilizer market due to COVID-19, replacement value of nutrients are likely higher than normal
- N – $22.40/ac, P – $7.35/ac, K – $29.95/ac, plus trace micronutrients
- Total N-P-K value = $59.70/ac
Straw also contains valuable Organic Matter that is hard to replace
- Ensure that you have a plan in place for manure/compost/cover crops to regain some of what is lost
At the end of the day, having cereals in the rotation even with straw removed is better than not having them at all. Soil structure, organic matter, and following corn and soybean yields are all improved from the rotation aspect of cereals alone. Not to mention the potential to get some living roots in the soil with cover crops after the wheat is off.
Ultimately, there is value in the straw both on and off the field, but you must be aware of how it affects your crop’s fertility. A soil sample is a great way to figure out exactly how value the straw is to your individual field based on the underlying fertility alone. As well as a necessary part of the 4R management of your crop.