Reports on spring wheat and durum yields from across North Dakota are positive, with yields sometimes double what might have been expected given the late planting season.

“The higher spring wheat and durum yields are a testament to the importance of a full soil profile of water, a cool growing season and low in-season rainfall,” says Dave Franzen, North Dakota State University Extension Service soil science specialist. “However, across the state, there are many reports of abysmal protein levels. Normally, protein falls in the 13 percent to 15 percent range. This year, early protein reports are 9 percent to 14 percent.”

Franzen says there are a number of factors that may have contributed to the lower protein levels. In some cases, growers may have experienced more than one of these factors.

• High early season rainfall and flooding

Although many soils were frozen when the most serious flooding occurred in April, the soils thawed relatively fast once flooded. This sometimes left the soils saturated in an unfrozen condition for a couple of weeks.

“Water saturation in the eastern third of the state can lead to a gaseous loss of nitrates due to denitrification bacteria,” Franzen says. “After the water left the fields, there probably was virtually no available nitrogen (N) left in the top 2 feet of soil. If soil residual nitrate available N was factored into the N rate for these fields, the field likely was underfertilized from the beginning of the season.” He adds, “Soils in the west are not as prone to nitrous oxide gas loss, but there was nitrate leaching in coarse-textured western soils this spring.”

• Questionable field conditions for incorporation of urea or application of anhydrous ammonia

To say that field conditions were seldom ideal across the state for incorporation of urea or the application of anhydrous ammonia is understating the facts, according to Franzen. When the soil was worked, instead of a nice seedbed with good distribution and coverage of urea, there were clods and gaps. These conditions lend themselves to N loss from ammonia volatilization.

In addition, little rain fell after the serious flooding conditions abated, so rainfall did not incorporate the urea that was not adequately worked into the soil. Anhydrous ammonia was applied to soil that was often wet a few inches below the soil surface. This led to ammonia losses during the course of several days following the application.

Many growers still suffered from inadequate application trench coverage at the time of application. A nice inch of rain a couple of days after application would have made most of these two problems a nonissue, but most areas received no rain for several weeks after planting.

• The continued mistake of applying urea to the soil surface in no-till fields

“Many growers continue to believe that it will rain shortly after urea is applied to no-till fields,” Franzen says. “This year, it didn’t rain. Urea applied to the soil surface and not incorporated by rain or steel will volatilize, as it probably did in many fields this year.”

• Continued wetness of fields through June in many areas

Although it finally became possible to seed in the far eastern Red River Valley about May 25, the silty-clay loam soils continued to be wet and nearly saturated near the soil surface for several weeks. Nitrate from a fertilizer application likely succumbed to denitrification during this period.

“My own campus tillage plots received 150 pounds of N per acre as urea incorporated in the conventional-till plots, but N deficiency symptoms still appeared at tasseling the first of August,” Franzen says. “The field had received little rain since early May, but soil a few inches below the surface was still wet about July 1.”

• The most scab-tolerant wheat varieties are not stellar protein varieties

Alsen is not a protein blockbuster variety, but N-rate trials sometimes resulted in near 15 percent protein at the highest N rates.

“Faller seems to be even stingier with protein and so are several other good scab-resistant varieties,” Franzen says. “It may be necessary to boost N rates on these lower-protein varieties to make sure that they reach the protein minimum to avoid dockage in future years.”

• Anticipation of lower yields with a later seeding date

“One of the problems with our current N rate formula and why I will change it Dec. 1 is that the N rate formula tries to be predictive,” Franzen says. “It can’t be predictive because the N rate can’t predict yield. Specific yields shouldn’t be used to predict N rate. “Yes” to general productivity through time leading to ranges of N rates, but “no” to specific yield guesses to predict an adequate N rate for a season.”

Because of the use of the wheat N rate formula for the last 30 years, it is a part of many growers’ psyche to look at conditions and date at planting to assume things are going to be either better or worse than average. This year was a good example. Coupled with high N costs, the late seeding date and memories of 90 degrees in late June and July led some growers to fertilize very productive soils only modestly in anticipation of perhaps a 40- bushel-per-acre yield. However, producers harvested more than 70 bushels per acre in some cases. Even if they received high efficiency out of their N fertilizer application, which is doubtful, these fields were doomed to have low protein as soon as the tillers formed, spikelet number was determined and the spikelets filled with enormous amounts of grain.

It has been suggested that poor in-season organic matter/residue mineralization might be a cause for lower protein.

“Early returns in this year’s wheat N rate studies suggest this was not a cause,” Franzen says. “In fact, this year might have been a great year for mineralization given the moderate temperatures and generally moist subsoil conditions. Check plot yields at Valley City in medium- to higher-productivity environments on 2.5 percent to 3.5 percent organic matter soils were similar in yield to N rates of up to 150 pounds per acre, with only 20 to 40 pounds per acre residual soil nitrate in April. The medium-productivity plots averaged about 40 bushels per acre and the higher-productivity area while higher organic matter averaged about 60 bushels per acre. Sixty bushels per acre spring wheat yields, with only 40 pounds of N per acre residual soil nitrate in April, suggests a large amount of soil mineralization during May and June.”

NDSU Agriculture Communication