Friday, October 4, 2013

Good Corn Yields Despite Nitrogen Losses

Chad Lee, Extension Agronomist, University of Kentucky

Excellent seed fill,
even though N deficiency is evident.

Corn in most fields across the state displayed nitrogen (N) deficiency before black layer was reached. Those losses were expected this season as we experience more rain. Normally, we expect yield losses to occur when the corn crop runs low on N before the seeds are done developing on the cob. However, walking some of these fields reveals that corn yields should be very good despite the apparent lack of N.

The corn ears in the first image have kernel fill to the tip. Kernel set appears uniform and the kernels have good depth. A lack of N did not hinder these key components for yield. The lack of N could reduce kernel test weight. But, all things considered, the corn in this field should have minimal losses from the lack of N.  

The temptation from this season will be to apply more N next season. Much of the N loss in Kentucky this season was from saturated soils where the nitrogen forms in fertilizer were converted to nitrogen gas (N2) and lost to the atmosphere. There are options to better manage against that risk without necessarily applying more N fertilizer. More will come later about managing next year's corn crop and N considerations. For now, let's be thankful that corn crop looks relatively good despite N losses.

Typical N deficiency symptoms.
Early leaf drop resulting
from a lack of N.

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