Growers are doing a better job of managing nitrogen fertilizer applications. In recent years, the amount of fertilizer used has remained relatively constant while average yields have steadily increased. DuPont Pioneer experts suggest growers continue to look for ways to make nutrient application — particularly nitrogen — as efficient as possible. One strategy is to adopt split applications.
“Modern hybrids take up nitrogen later in the growing season,” says John Shanahan, DuPont Pioneer research scientist. “Data suggest applying nitrogen during the growing season, to coincide better with crop uptake of this nutrient, can result in higher yields.”
Spring application of nitrogen leaves less time for leaching than fall application, but unpredictable weather can make it difficult for some growers to get into the field.
“Early planting trends can work against spring applications,” Shanahan says. “Many growers want to get seed in the ground as early as practical, and they don’t want to deal with fertilizer application if it may delay planting.”
Recent work by Tony Vyn at Purdue University demonstrates a substantial positive impact from applying nitrogen after planting. This is not surprising, as crops require the lion’s share of their nitrogen needs just before the reproductive stages.
“Growers must overcome some obstacles to make a second nitrogen application in season,” Shanahan says. “They need high-clearance equipment, which is expensive. They’re also at the mercy of weather: Can they get into the field in a timely manner to get the second application down?”
Because of the complex nature of soil and weather variability, growers face significant challenges in optimizing the amount of nitrogen to apply to each field, year and area within a field. This results in under-application of nitrogen in some years and fields, with resulting yield losses and over application of nitrogen in other years and field areas resulting in inefficient use of nitrogen resources.
“Generally, it pays to avoid putting all your nitrogen down at once.” Shanahan says. “Today’s genetics show potential to deliver more bang for your buck through split applications.”
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