Farm Progress

• Getting the wheat crop through the winter and into warmer spring weather and heavy grain-set is going to be critical to producing high yields and good profits.• North Carolina State University Small Grains Specialist Randy Weisz says a simple thing like splitting nitrogen application can mean big yields and big bucks for growers.

Roy Roberson 2

February 6, 2012

6 Min Read
<p> <em><strong>WHEAT PLOTS show color variation based on date of nitrogen application in North Carolina on-farm research.</strong></em></p>

Wheat growers in the Carolinas are coming off one of their best years in recent history, and with wheat prices still good, another large crop is in the ground and by all accounts looks like another good one.

Getting the crop through the winter and warmer spring weather and heavy grain-set is going to be critical to producing high yields and good profits.

North Carolina State University Small Grains Specialist Randy Weisz says a simple thing like splitting nitrogen application can mean big yields and big bucks for growers.

At a field day in Rowland, N.C., last spring, the North Carolina researcher showed growers the results of different timing of nitrogen application.

In a block of wheat planted at 35 seeds per square foot, he got the expected thick stand. Coming into February, he had a stand above the threshold at which it is recommended to apply early nitrogen. If wheat looks that good, no nitrogen should be applied to your crop in February, Weisz says.

In one test 120 pounds of nitrogen per acre was applied to this wheat in early February. Weisz points out that this is exactly what the North Carolina Wheat Production Guide says NOT to do.

In an adjacent plot, half the recommended rate of nitrogen (60 pounds per acre) was applied in February and the other half was applied at normal lay-by in mid-March.

When the nitrogen was applied becomes critically important if you skip over from May of 2011 to February of 2012.

One advantage of the ongoing La Niña weather pattern is that it is a great environment to grow wheat in the Southeast.

Crop running on time

Thanks to a good harvest season for spring planted crops last summer and fall, much of the area’s wheat crop was planted on time and has benefitted from mild winter weather up to February.

As a result of this perfect storm of economic and environmental criteria, much of the wheat in the Upper Southeast is in a similar situation as was the wheat Weisz showed at the field day last May.

Standing in front of what looked like a beautiful stand of wheat in Rowland, N.C., Weisz pointed out the obvious.

“If you look at this wheat, it looks pretty good.” He was referring to the wheat that had all the nitrogen applied in February.

Then he pointed out the not-so-obvious. “Notice the difference in color between the two plots. The all-in February plot was beginning to run out of nitrogen by mid-May, and to the trained eye it was clearly not going to produce as much wheat as the neighboring crop that had the same rate of nitrogen applied in mid-March.

The early nitrogen wheat also had much more disease pressure than the late planted wheat. “By putting out the full rate of nitrogen in February, wheat gets a big growth spurt, it gets tall quickly and grows to a thick stand early in the season. These factors make it much more vulnerable to diseases than later maturing wheat, Weisz says.

A third option is to use a split application of 60 pounds in February and 60 pounds in March. Under the growing conditions last year, which appear to be very similar to what the 2012 winter-spring conditions look to be, the split application did not yield as well as the one-time March application.

In another test plot, wheat was planted at a much lower seeding rate, producing a stand similar to what growers would find when they are delayed harvesting corn or cotton and don’t get their wheat planted on time.

“On these plots, we had less than 50 tillers per square foot in early February. This fits our criteria for putting out a split application of nitrogen,” Weisz says.

“By applying the full rate of nitrogen (120 pounds per acre) we stimulated tillering and produced more heads per square foot. The big dose of nitrogen did appear to give the wheat crop what it needed to recover from low February stand counts.”

An adjacent plot was clearly not as lush and green, and more importantly it had noticeably fewer plants per square foot. Again, this treatment was the reverse of what is recommended. These wheat plants were given the full rate of nitrogen, but it was applied in mid-March.

The same variety of wheat, the same growing conditions, same soil, etc., produced high yields from late nitrogen and also low yields from late nitrogen. The only difference was plant stand.

“Good stand, late nitrogen and poor stand early nitrogen. Seems simple enough, but it requires growers to apply nitrogen at two different times, and often that just doesn’t happen — for a plethora of well-intended reasons.

“In the lower plant stands, we would normally recommend a 60-60 split of nitrogen in February and March. The wheat specialist didn’t have to do much explaining to growers attending the wheat field day in Rowland. Neither late applied nitrogen nor early applied nitrogen performed well in the side-by-side test conducted on this farm in southern North Carolina.

“These plants clearly haven’t tillered well and we don’t have enough plants per square foot — we needed a dose of nitrogen as early as possible to get a better stand and second dose in March to get a better yield,” Weisz says.

North Carolina Department of Agriculture Agronomist Ben Knox says a series of similar test results across the state led to recent changes in recommendations for nitrogen application on wheat.

The revised guidelines take into account crop biomass and often call for significantly less nitrogen than previous recommendations.

Growers lucky enough to have a stand, despite the poor planting conditions last fall, may be able to use the new guidelines to reduce input costs without compromising yield.

“If the tiller count is low, growers should put out some nitrogen as soon as possible,” Knox said.

“If there are fewer than 50 tillers per square foot of row, growers need to apply up to half (about 60 pounds) of the spring nitrogen now. For counts between 50 and 70 per square foot, 30 to 40 pounds of nitrogen should be applied. If the tiller count is high, but the wheat is yellow, an application of 30 pounds of nitrogen is appropriate.

“I have seen fields with as few as 15 to 20 tillers per square foot at this time of year end up making good wheat,” Knox said.

“A timely nitrogen application, followed by some dry weather and warm temperatures, can yield surprising results. However, even if the wheat is thin and has to be abandoned, the nitrogen will not have been wasted. It will have made the wheat a better cover crop.”

As Carolina-Virginia wheat growers approach the critical time for applying nitrogen to their crop, Weisz offers some common sense advice that would bode well for optimum production.

“My former colleague in Virginia, Dan Brann, used to say if you have thin wheat there is no job on the planet that pays a higher hourly rate than applying nitrogen to a thin stand — the yield differences are that high,” Weisz says.

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