Splitting nitrogen in a corn crop can increase profitability and benefit the environment, but to be successful on both counts growers need to keep a sharp eye on the weather.
That’s the conclusion drawn by University of Guelph researchers Tasmia Kabir, Aaron Delaporte, Joshua Nasielski, and Alfons Weersink after looking at 19 years of weather data from Ontario’s Elora Research Station to develop nine different weather scenarios. They also analyzed corn yield and nitrogen loss to measure the profit of nitrogen management practices used in each weather scenario.
The study focused on three different nitrogen management practices: traditional pre-plant broadcast urea at 120 lbs/ac; 60 lbs/ac pre-plant urea followed by a split application at V6 of UAN; and 60 lbs/ac pre-plant urea followed by split application at V13 of UAN.
On this episode of RealAgriculture’s Corn School, Nasielski explains that the most profitable and environmental strategy for a given year really does depend on the weather. The research shows that splitting nitrogen applications and adjusting the second application rate based on weather, increased farm profit and reduced nitrogen losses to the environment only in dry years.
Split nitrogen applications increased farm profit from 15 to 20 per cent in dry seasons, and from one to 16 per cent in wet seasons, compared to pre-plant broadcast. (Story continues after the video.)
Comparing application timing, it was more profitable to make the second nitrogen application just prior to silking (V13) than at the six-leaf stage, except in wet and cold seasons.
From an environmental perspective, the researchers found that split applications reduced both nitrate leaching and nitrous oxide emissions up to 24 per cent, and ammonia volatilization losses up to 55 per cent compared to pre-plant broadcast. Overall, making the second application at V13 minimized nitrogen losses in all weather conditions.
But management that minimized losses to the environment did not always maximize farm profitability. Split nitrogen applications maximized both economic and environmental benefits only in dry seasons.
Nasielski notes that in an average season, split nitrogen actually reduced profit by nine per cent, due mainly to in-season custom application costs and a two bu/ac yield penalty when nitrogen is delivered at V13 in average conditions.
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