New research is showing nitrogen applications to corn are most beneficial when the plant needs it: before planting and during growing season by tassel. Studies from DuPont Pioneer and Iowa State University show that newer corn hybrids need nitrogen available later into the growing period.
Extensive Pioneer research conducted over the last five years has shown that nitrogen needed for grain development is derived from both remobilized nitrogen (from leaves and stalks) and continued nitrogen uptake from the soil. In fact, modern hybrids have very different patterns of nitrogen uptake compared to older hybrids – less of their total nitrogen supply is taken up early, and more is extracted during reproductive development.
“Studies from 20121 and 20132 showed that new hybrids took up 29% and 40% more nitrogen post-flowering, respectively, than older hybrids," explains DeBruin. “Evaluation of Pioneer brand hybrids marketed from 1934 to 2013 also supports these findings.”
In addition, Iowa State University studies indicated that at high yield levels (225 bu/acre), 70 lbs. of nitrogen/acre must still be taken up post-flowering to support grain development3. Without that additional soil-extracted nitrogen during grain fill, corn yields would be severely limited.
There are three steps growers can consider to help ensure adequate nitrogen availability:
- Apply 70% of the total seasonal nitrogen requirement prior to planting to help provide sufficient nitrogen for vegetative growth.
- Apply the last 30% of required nitrogen as late during the growing season as ground equipment allows, but generally by tasseling.
- Add a nitrification inhibitor to the late application to help delay nitrogen release.
To learn more about nitrogen uptake in corn, see the Crop Insights on pioneer.com.
1Ciampitti, I.A., and T.J. Vyn. 2012. Physiological perspectives of changes over time in maize yield dependency on nitrogen uptake and associated nitrogen efficiencies: a review. Field Crops Research 133:48-67.
2Haegele, J.W., K.A. Cook, D.M. Nichols, and F.E. Below. 2013. Changes in nitrogen use traits associated with genetic improvement for grain yield of maize hybrids released in different decades. Crop Sci. 53:1256-1268.
3Abendroth, L.J., R.W. Elmore, M.J. Boyer, and S.K. Marlay. 2011. Corn growth and development. PMR 1009. Iowa State University Extension and Outreach, Ames, Iowa.
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