I was talking to a crop consultant this week in western Kansas. Harvest is underway in that area and he indicated he was seeing protein coming in lower than anticipated, as well as lower than normal.
Farmers in Western Canada and the United States northern Great Plains can use this as a signal that protein premiums may be higher than average this fall. To try and capitalize on this, growers can try to influence their protein content over the next few weeks.
Protein is impacted by two factors. Firstly, the higher the yield, the lower the protein. This is called the dilution factor. There may be the same amount of protein per kernel in two samples but the plump kernel has more starch and the protein content will be lower. Things that increase the yield and correspondently decrease protein include water and growing conditions, which are outside our control, as well as fungicides.
The other factor is nitrogen. The largest impact on yield is the amount of protein in the soil. The higher the nitrogen, the higher the protein.
However, recent work done in North Dakota by David Franzen, North Dakota State University Extension soil scientist, suggests that an application of UAN (28-0-0) at anthesis can increase the protein content of the wheat.
Franzen’s work has shown that the most efficient way to accomplish this is to apply 30 pounds of nitrogen per acre, 10 U.S. gallons each of UAN, plus 10 of water, immediately post-anthesis before the wheat berry starts to become milky. This product should be applied using flat fan nozzles.
The best time for application is in the coolest part of the day, which is usually early in the morning. Producers should stop when the temperatures reaches 15 C. On cool, cloudy days when the temperatures are between 10 C and 15 C, spraying can continue all day. Some fertilizer burn can occur but research has shown that very little or no yield loss can be attributed to the burn.
Avoid applications to drought-stressed crops. Your protein will already be higher. This practice should result in a protein increase of 0.5 to one percent.
So how do you determine if you should apply some top-dress UAN? Measuring flag-leaf nitrogen concentration, the uppermost leaf of the stem sampled at heading, can give you a good indication of the success of a late-season nitrogen application on increasing grain protein.
***Research by Brown and Petrie reported in 2006 showed that nitrogen application is likely to increase with late-season nitrogen if the flag-leaf nitrogen concentration is less than 4.2 percent. ***
To get a result, select 50 or more flag leaves broken off at the stem randomly selected from a zone. These should be put into a paper bag or envelope with aeration holes punched. This can then be sent to a lab for analysis. The lower the flag-leaf nitrogen concentrations the higher potential response to late season nitrogen, but more nitrogen will be required to reach high protein. The amount of protein increase with late nitrogen relative to flag-leaf nitrogen varies with year and may vary among varieties.
As well, a rainfall after application impacts the results because the rain will wash nitrogen into the root zone of the wheat. I ask for a nitrogen concentration test. I have used Farmers Edge Lab in Winnipeg, but other labs will also do the test. Phone to confirm prior to shipping. Expect a three- to four-day turn around for results.
Once you get the results, run some economic scenarios to decide if an application will pay. Use the price of fertilizer and the cost of application vs. the anticipated price increase. Then decide if the risk is worth the reward.
Thom Weir PAg is certified crop adviser and professional agrologist in the Yorkton, Sask., region. You can reach him at firstname.lastname@example.org.