Split decisions
AN EARLY APPLICATION OF NITROGEN MAY BE THE DIFFERENCE BETWEEN A GOOD WHEAT CROP AND NO WHEAT CROP
FARMING, TO SOME degree, is in Mother Nature’s hands. With the late soybean harvest and subsequent late winter wheat planting, there is cause for concern for next year’s wheat crop. This upcoming spring is shaping up to look similar to last year says Peter Johnson, wheat specialist with OMAFRA. With roughly 12 percent of the wheat crop plowed under last spring, that’s not exactly a rosy outlook.
Fortunately, there are management techniques farmers can use to avoid the pitfalls some fell into last year. The key to ensuring a good wheat harvest in 2010, says Johnson, is to really focus on early management.
“That’s one of the balls some growers dropped this past spring. The wheat crop was in tough condition in spring 2009 because of a wet fall and a tough winter. March 15 rolled around and growers didn’t want to touch the field before they knew if it was worth keeping,” explains Johnson. But, he continues, this early application of nitrogen, despite the uncertainty of the stand, is important.
When it comes to nitrogen, Johnson does not typically advocate for a split application. However, he explains, “wheat that hasn’t had an opportunity to tiller in the fall needs as much help as possible in the spring.” With the cool temperatures experienced this fall and late planting dates, there is a good chance many acres will not have tillered before snowfall.
WHAT AND WHEN TO APPLY
“With a struggling wheat crop in the spring, you should apply between 30 and 60 pounds of nitrogen early,” says Johnson.
Targeting the last frost is the ideal time for early application. However, predicting the last frost can be difficult and if it’s missed, the ground will be too soft for an early pass. With this in mind, Johnson recommends mid-March for early applied nitrogen. “Going in February is too risky; you could easily lose half of the nitrogen through denitrification and leaching. Waiting until the end of March is also risky because you may lose the frost,” elaborates Johnson.
In addition to getting the timing right, farmers also must be cognizant of what they are applying. “It’s best to put nitrogen on in a form that is readily available to the plant. Fertilizers containing soluble ammonium or nitrate (ammonium nitrate, ammonium sulphate or UAN) are the best options,” says Johnson.
He doesn’t recommend urea for an early application because, although it’s a good source of nitrogen, it takes time to break down before it is available to the plant. In cool conditions, urea can take 10 to 14 days to become available. In a situation where an early application is needed, it’s important the plant can readily access those nutrients.
Along with taking advantage of the frost, applying nitrogen in mid-March is ideal because “wheat is a base zero crop, meaning we count heat accumulation any time the temperature is over zero degrees,” explains Johnson. Wheat starts early and will continue to grow at much cooler temperatures, making mid-March an appropriate target. The nitrogen should be available to the crop as soon as it begins to grow.
SECOND APPLICATION
The balance of the nitrogen should be applied in the last 10 days of April. This timing is typical for most of Ontario, give or take a few days, and in years when proper tillering is accomplished in the fall, this is often the only application necessary.
The early application in mid-March can provide a little more flexibility for the second application. However, Johnson warns that the second application should be on before the growing point comes above the ground or Zadocks 30. Typically, this happens around the first of May. Johnson explains, “if the nitrogen is applied after this point, every wheel track is going to cost you in yield.”
WORST CASE SCENARIO
The reason many farmers didn’t use this management technique last year is the fear of applying nitrogen to a crop that is going to be plowed under. Unfortunately, waiting to see if the crop will be viable is waiting too long.
However, if nitrogen is applied and it can’t give the crop enough of a boost, plowing it under will not mean all is lost.
“If the wheat doesn’t make it, that crop should go to corn and the corn will use that nitrogen,” says Johnson. He continues to explain that, “you will lose some of the nitrogen, but not a whole lot. Expect to lose about 10 to 20 percent, although this will heavily depend on the spring.”
This risk is one of the main reasons for only applying between 30 and 60 pounds during the early application. “It’s too risky to apply all of your nitrogen in mid-March,” says Johnson.
PLANNING YOUR STRATEGY
Farmers who were able to get their wheat planted early this fall will not need to use this management technique. However, with the majority of acreage being planted after a late soybean harvest, many farmers should consider a split application of nitrogen in the spring.
“Last year, which is expected to be similar this upcoming spring, this early management technique paid huge dividends and was often the difference between a respectable wheat crop and no wheat crop,” concludes Johnson. •
