Quinn stated that she believes (nitrogen rate calculators are) important tools that people can use, especially in this year’s climate with the high prices of nitrogen and corn.
According to Nafziger, a 2021 University of Illinois N rate trial in corn showed that soybeans yielded more when the economic N rate was used than the maximum yield.
An N rate of 207 pounds per acre would have a maximum yield of 242.5 bushels/acre (bpa) on average. The economic optimum rate for N was 178 pound per acre, which produced 240.3 BPA. When calculating the economic outcome of the trial, the university used 75c per pound for N as well as a $5 per-bushel corn price. Although the maximum-yield N rate produced more than the economic rate N rate which generated $10.90 per annum in additional revenue, it lost $10.85 per annum to the maximum yield rate N rate.
This (economic optimum N-rate) approach is not for you if your goal is to maximize yield and not maximize profit. It’s designed for maximising income,” Nafziger stated.
Purdue University revised Indiana’s corn-nitrogen management guidelines. These guidelines include economic optimum nitrogen rates. It can be found at https://thekernel.info/….
SPLIT APPLICATIONS
Quinn explained that corn should be given N when it is most needed or as close as possible to that time in order to improve its N-use efficiency. University of Illinois research shows corn requires between 25 and 30 pounds of N per an acre in the VE and V6 stages of growth. The rest of its requirements are during the rapid-uptake phase and grain fill periods, which is V7 to R6.
Quinn advised farmers to avoid applying fall N if at all possible. Leaching is more likely the longer nitrogen stays in the soil. This can lead to decreased yields and a worse environment.
Quinn suggested that farmers include a nitrification inhibitor in fall N applications, namely anhydrous Ammonia. Nafziger and he both noted that fall N applications do occur and will likely continue. Quinn and Nafziger both noted that more anhydrous ammonia were applied last fall than previous years because of escalating N costs and concerns about N availability in spring. “I know of farmers who paid $730 for anhydrous (less then half of the current price). Nafziger stated that she hoped that many people could do the same.
Quinn’s replicated research at the University of Kentucky found that split-applying N at planting or in-season is more effective than pre-plant applications. From 2018 to 2020, studies were conducted at three locations. UAN32 was used as the only N source.
It took 215 pounds of preplant N per acre (185 pounds applied a day prior to planting and 30 pounds at the planting) to achieve a maximum yield for corn after soybeans without a cover crop. Split-applied N required an average of 187 pounds — 30 pounds at planting and the remainder sidedressed during the V6 stage — to achieve 217 bpa.
Quinn stated that Quinn was struck by the differences between pre-plant nitrogen and split-applied nitrogen, and how much and what yields are at different rates. Split-applied is a better way to apply nitrogen. We had less nitrogen loss in that system.
PROTECT N
Nitrification and Urease Inhibitors reduce N volatilization and increase the likelihood of corn utilization.
Quinn advised farmers to use anhydrous ammonia in the fall when soil temperatures are 50°F and trending down. This slows the transformation of ammonium to nitrate and reduces denitrification.
Quinn advised that a urease inhibit is recommended for surface-applied UREA or UAN. This will reduce N loss. A urease inhibitor can stop volatilization for seven to 14 days, depending on whether it is applied in the spring or autumn.
Quinn stated that a urease inhibitor is not usually required if urea or UAN are incorporated into the soil.
Quinn stated, “It’s really about trying to minimize or spread risk out of losing fertilizer nitrogen once applied.” “Loss in nitrogen is lost money, lost yield.”
CONSIDER THE HYBRID SELECTION?
Jeff DeBruin, Corteva Agriscience research scientists, studies, amongst other things, whether certain corn varieties use N more efficiently than others without sacrificing their yield. This could be part future breeding programs. Hybrids that require less N to perform well could lower N usage, save farmers money, and help the environment if there is less N to be lost.
DeBruin claimed that certain hybrids use N more efficiently in certain years and at different locations in research, but the data aren’t consistent enough to make any claims.
DeBruin suggests that farmers don’t try to match a specific crop to a nitrogen program. DeBruin says it is better to split-apply nitrogen at the right time for the crop and protect it from loss with N stabilizers when necessary.
He said, “Go for high-yielding hybrids” and that nitrogen should be managed in relation to the environment.
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