Result for: Crops: Corn for grain
4R Practices: Place

Supplemental Late-vegetative N Applications for High-yield Corn: Agronomic, Economic, and Environmental Implications with Modern versus Older Hybrids

Dr. Tony Vyn

Lead Researcher:

Dr. Tony Vyn

Department of Agronomy, Henry A. Wallace Chair in Crop Sciences

Purdue University

Start Date: 2014

End Date: 2017

Collaborating scientists and universities

  • Dr. Sarah Mueller, Purdue University

Matching Funds

  • USDA-National Institute for Food and Agriculture
  • Corteva Agriscience – Pioneer Hi-Bred

Project Summary

Modern corn hybrids have a “functional stay green” capacity whereby their leaves not only stay green longer during the grain filling period, but also maintain their photosynthetic capacity until much later in the grain filling period. Modern hybrids also yield more than hybrids of earlier decades because of their improved stress tolerance to plant density and other stress factors (whether pest-related factors or abiotic challenges). Therefore, one of the major corn management questions of our time is whether corn hybrids take up more of their total plant N during the reproductive period and, if they do, whether modern hybrids are more responsive to intentionally very late vegetative stage N fertilizer applications. We know that part of the positive response of modern corn hybrids to higher N rates is that total plant and grain uptake of other nutrients like P and Zn also increase.

Perhaps one of the more difficult negative environmental consequences to monitor with corn production systems is that of management consequences on greenhouse gas emissionsThe cropping systems group at Purdue University has also done extensive work on monitoring greenhouse gases in corn production systems over the last 10 years, as the largest single pathway to reduce N2O losses to the atmosphere is to increase the N uptake by corn plants itself. This can be addressed by focusing on enhancing crop yield and total plant N uptake while minimizing N2O emissions.  

Project Goals:

  • To determine the extent to which modern hybrids are likely to be more yield-responsive to late-vegetative N applications than hybrids of 20 years ago, and the physiological reasons for those differences if, indeed, modern hybrids are more responsive. 

  • To evaluate the opportunity for split N applications involving an intentionally late vegetative N application to reduce season-long and cumulative N2O emissions relative to a single early side-dress N application strategy. 

  • To use a partial budget approach to determine the economic implications of late-season N applications (whether supplemental N is applied, or whether a normally recommended N rate is side-dress applied both early and late) in high-yield corn production systems relative to a single-time, side-dress N application. 

Project Results:

  • New Era genotypes increased the proportion of the total plant N at maturity accumulated post-silking (percent PostN) as N stress levels at R1 increased—demonstrating improved adaptability to low N environments.

  • New Era hybrids maintained similar GY on a per plant basis under both low and high N stress at R1 despite being subject to much higher population stress.

  • PostN is more strongly correlated to GY (both eras combined) when under severe R1 N stress than under less acute N stress at R1.

  • The New Era accumulated more total N (an increase of 30 kg N ha−1) and higher %PostN (an increase from 30% in Old to 36% in New Era).

  • The change in stover dry weight from silking to physiological maturity (ΔStover) has a positive, linear relationship with PostN in the Old Era but less so in the New Era.

Annual Reports