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Wheat Protein Factors

University of Minnesota Extension, Stearns County News
March 9, 2016        
Source:  Dan Martens, Extension Educator
University of Minnesota Extension
Stearns, Benton & Morrison Counties

Wheat Protein Factors
By Dan Martens, University of Minnesota Extension

FOLEY, Minn. (03/09/16) — Since writing recently with notes from a U of M Extension Small Grains Workshop in February, I got a call from someone hauling wheat to market and getting docked significantly for protein less than 14%...with questions about doing better. We don’t grow a lot of wheat in this area, but for where it might be useful, here’s a little more discussion.

I had the impression from the call, they were hauling wheat now. Doug Holen said at the workshop in February, that storing wheat can be important part of a marketing plan. Typically, discounts for protein or other issues are more severe during harvest. Discounts might persist longer with an abundant crop.

Doug said pulling samples from the center of the load is better than from the edges or corners. You might watch how samples are taken, aiming to get a representative sample. Maybe that’s something to think about with other grain too. I shared in a previous article that one strategy might be to grow some acres with a high protein (but average yield) variety like Bolles, to have some higher protein wheat to blend with better yielding varieties that might not make the 14% protein standard. 

Along with selecting varieties with good yield and protein potential, applying nitrogen correctly is also a key to protein. Other crop stress could be a factor too. Extension guidelines are based on previous crop, realistic yield goal, and soil organic matter, where low is less than 3%, medium to high is 3% or more. With a past crop of soybeans, medium to high organic matter, and a 40 to 49 bushel yield goal, the suggested nitrogen rate is 40 pounds per acre. With a past crop of corn, it is 60 pounds. For low organic matter that changes to 60 pounds after soybeans and 80 pounds after corn.

If we move to 50 to 59 bushel yields, this changes following soybeans to 85 for low organic matter and 65 above 3% organic matter. Following corn it changes to 105 for low organic matter and 85 with medium to high organic matter. Higher amounts of nitrogen, especially on sandy soils might be split between pre-plant and a later application.

There are nitrogen credits where wheat follows some other crops too, and for manure and alfalfa of course. So it’s useful to get the tables to take a closer look at your own situation. It’s also helpful to understand how weather and other factors might affect N credits. A 24 inch soil nitrate test can be used west of Highway 71. There can be some limits to how much fertilizer you can mix with wheat when using an air seeder. I wrote last week about seeding depth. That raises questions about air seeding.

Then let’s look at information related to providing more nitrogen (N) later in the summer. The U of M Extension guide says, “In-season applications of liquid urea ammonium nitrate solutions (28 or 32% UAN) from 2 to 5 days after anthesis (that means pollination) have been shown to increase protein. This is particularly true when later expected yields are greater than the normal yield goal used for early season decisions. Research shows that protein can be raised by one-half to 1% by an application of 30 pounds of N per acre at this time. Some leaf burning can be expected, but generally will not result in lower yields.”

Another CAUTION is “Do NOT tank mix UAN solutions with fungicides.” That’s tempting with weather conditions that favor disease issues at this stage because there could be benefit to a fungicide application right around flag leaf time. But the mix is NOT advised and the additional N would be applied later than flag leaf. It might seem like a few days to a week or so doesn’t matter, but it surely does. Timing can be a challenge.

Last summer might have been a time where extra Nitrogen could have made a difference. With a cool spring, good tillers and heads, and ample moisture, it could have been expected at heading time that wheat could produce better yields. It could also be that heavy early season rain could remove some of the nitrogen applied earlier. Farmers should also consider damage caused by making a trip over the field, and cost versus potential gains. You’re welcome to call for printed information or check the Extension small grains website.

Please make SAFETY an important part of preparing for the spring work season.