Nitrogen is one of largest expenses for corn production and new research is finding ways to improve plant uptake while decreasing costs to producers. Academic researchers in the Midwest have spent countless hours and multiple decades determining the best rate and time of application for nitrogen in corn production.
New hybrids of corn have shown an increased demand for nitrogen. Not only is their total uptake higher, but the timing of the uptake is also different than corn varieties in decades past. Tony Vyn, Professor of Agronomy at Purdue University, and doctoral student Sarah Muller have found new hybrids are more likely to take up 30 to 40% more nitrogen after flowering stage than earlier hybrids.
With this new information, there can be a greatly increased rate of plant uptake by applying nitrogen at the right time and meeting plant demand. “So there appears to be more room for a positive response to applying 20 to 30% of total nitrogen after the V10 stage in modern hybrids,” Vyn says, while adding discretion for variability of response depending upon soil and environment circumstances.
These results can have a positive impact on environmental concerns with nitrogen leaching and run off. With increased concern with water quality and the impact of nitrogen run off to municipal water sources and hypoxia in the Gulf, this can be a win-win solution for agriculture production and the environment. By integrating the application of N with the when the plant can best utilize it, producers can increase their return on investment while minimizing negative environmental impacts.
University of Missouri research is looking at N application and how variable application can decrease nitrogen costs for producers. Peter Scharf, nutrition management specialist with Missouri Extension, has studied nitrogen application while taking into account many variables producers encounter every day including variable soil properties and change in weather conditions from one growing season to the next.
Spring-applied nitrogen has been favored over fall-applied for years and, with the increase in wet conditions, research is showing improved plant utilization of nitrogen when applied minimally in the spring with additional N applied later in the growing season. According to MU Extension climatologist Pat Guinan, 24 of the last 39 years have had above-normal precipitation. This leads producers to changing tactics on N application for optimal fertilizer use efficiency.
Scharf’s research builds on existing variable rate technology by incorporating the use of sensors to allow for real time data on when plants were demanding more nitrogen. Through the use of these sensors, nitrogen efficiency improved while nitrous oxide emissions and nitrates in drainage water were decreased by 50 and 24% respectively.
Soil tests and yield history have their place in determining N needs for a crop season, but Scharf has determined crop color as the most definitive method for determining nitrogen needs. He has developed yield-loss maps and nitrogen application files based on georeferenced aerial images of corn fields. “It’s taking the temperature of corn real-time,” Scharf says. “If it’s hot – dark green – it doesn‘t need very much nitrogen. But if it’s light green, you’d better pour it on.”
These aerial imagery systems are helpful when all N is applied preplant and losses have occurred due to wet conditions. Overall, it is important for producers to have a Plan B for nitrogen application due to the unknowns including weather, access to fertilizer, and available manpower.
Photo credit: Andrea Rice