Boosting fertilizer nitrogen to improve wheat yields
While increasing fertilizer nitrogen enhances wheat yields, growers need to be cautious as the risk of plant lodging is always a concern.
Research trials conducted in Michigan and Ontario have shown that wheat yields can sometimes be improved by bumping up fertilizer nitrogen (N) rates. This point was emphasized during a wheat management meeting held in Frankenmuth earlier this month. While the state-wide event generated considerable enthusiasm for hiking N rates, the take-home message also needs to emphasize caution as the risk of plant lodging is always a concern.
Most growers apply N at rates between 80 and 110 lbs/AC each spring. In research trials from 2008 to 2010, ratcheting up N rates to 135 lbs/AC or more resulted in improved grain yields in the absence of plant lodging. As some growers can attest from last season’s experience, this rate is far too risky for many commercial fields. Ultimately, the goal is to increase N rates but not to the point of causing plant lodging. So, what is being suggested is growers try increasing their spring time N rate by approximately 20 lbs/AC on a trial basis in selected fields. This increase might translate to the experimental rate of 110 to 130 pounds of spring time N.
To minimize the risk of plant lodging, the higher N rates should only be tried under the following circumstances:
- The grower knows the lodging potential of the variety being grown;
- The grower has experience growing wheat on the selected trial field and is aware of soil organic matter or other potential sources of N;
- The wheat crop has a high yield potential;
- N is applied uniformly (using UAN 28 percent with streamer nozzles may be the best way to achieve this); and
- All N is applied prior to jointing (growth stage 6).
To fully benefit from higher N rates, growers should plan to employ a fungicide as foliar diseases are often more severe in higher N environments. The best time to apply a fungicide is from boot to early flowering. However, the application at early flowering is encouraged as this timing has the advantage of providing protection from both foliar diseases and Fusarium head scab using Proasro, Caramba or Folicur.