Nitrogen (N) is typically the most yield-limiting nutrient and one of the largest input costs for corn production. DuPont Pioneer is aggressively working to develop hybrids that increase yield through improved N use efficiency. Researchers are applying transgenic, molecular and conventional breeding methods to enhance N utilization within the plant. Additionally, Pioneer continues to conduct extensive research on improved N application and management.
In multiple Midwest locations over the past 8 years, studies have been conducted to compare how cropping sequences and hybrids affect yield under a range of N fertility levels.
Previous research has shown that current hybrids seldom differ in their response to N. Recent studies supported these findings by showing that products of comparable maturity had similar yield responses over a range of N rates (Figure 1).
Results also showed a 44% yield advantage associated with rotation. The average yield for continuous corn was 115 bu/acre while corn in rotation yielded 165 bu/acre. Reducing N rates resulted in a much more substantial yield decrease in continuous corn than in rotated corn. In fact, rotated corn with no applied N yielded more than continuous corn that was applied with 70% of the optimum N rate (Figure 2).
The importance of N uptake prior to flowering cannot be overstated, as this N supports critical ear shoot development, kernel number and potential kernel size. However, research conducted over the last 5 years has shown that nitrogen needed for grain development originates from both remobilized N and continued N uptake from the soil; and that newer hybrids take up additional nitrogen postflowering compared to older hybrids.
A DuPont Pioneer study was conducted at Macomb, Ill., in 2012, comparing a “normal” rate of 200 lb N/acre with a "low" rate of 50 lb N/acre. Resulting yields averaged 250 bu/acre for the normal rate, and 100 bu/acre for the low N rate. In the normal N environment, 130, 170, and 301 lbs N/acre were taken up by V12, R1 and R6, respectively (Figure 3). Of the 195 lb N/acre contained in the grain at maturity, 63 lbs were sourced from remobilized N (from leaves, stalks, etc.) and 132 lbs were from N taken up postflowering (Figure 3).
In the low N environment (100 bu/acre yield level), N uptake was limited to 60 lbs/acre by R1, and only 27 lbs/acre were taken up postflowering (Figure 3). These reduced N levels simulate conditions when the pool of available N is low due to leaching, denitrification or under-application of N.
|AM - Optimum® AcreMax® Insect Protection system with YGCB, HX1, LL, RR2. Contains a single-bag integrated refuge solution for above-ground insects. In EPA-designated cotton growing counties, a 20% separate refuge must be planted with Optimum AcreMax products.|
|HX1 – Contains the Herculex® I Insect Protection gene which provides protection against European corn borer, southwestern corn borer, black cutworm, fall armyworm, lesser corn stalk borer, southern corn stalk borer, and sugarcane borer; and suppresses corn earworm. Herculex® I Insect Protection technology by Dow AgroSciences and Pioneer Hi-Bred. Herculex® and the HX logo are registered trademarks of Dow AgroSciences LLC.|
|YGCB – The YieldGard® Corn Borer gene offers a high level of resistance to European corn borer, southwestern corn borer and southern cornstalk borer; moderate resistance to corn earworm and common stalk borer; and above average resistance to fall armyworm.
YieldGard®, the YieldGard Corn Borer design and Roundup Ready® are registered trademarks used under license from Monsanto Company.
|RR2 - Contains the Roundup Ready® Corn 2 trait that provides safety for over-the-top applications of labeled glyphosate herbicides when applied to label directions.
Roundup Ready® is a registered trademark used under license from Monsanto Company.
All products are trademarks of their manufacturers.
Hybrid and variety responses are variable and subject to any number of environmental, disease and pest pressures. Individual results may vary.
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and management suggestions specific to your operation.
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