4R Nutrient Stewardship - Nitrogen

Now for the 4R nitrogen stewardship and management.  As I have said often here, nitrogen is the most difficult nutrient to manage.  It is critical for high yielding crops, but availability is affected by many environmental and biological factors.  In order to be the best stewards possible, we need to consider all those issues in our nitrogen management.  Nitrogen is critical for all the grass crops grown in our area including corn, grain sorghum, wheat, oats, and etc.  The crops start to need the nitrogen near to when it starts the grain production cycle;  in corn, right before tasselling.  In wheat, right before boot stage.  This means that nitrogen applications made closer to when the crop needs it will have the most likelihood of be utilized by the crop.  Also consider that later nitrogen applications require less nitrogen. 

All that said, I am hard pressed to say that fall applied nitrogen on corn is a good idea at any time, but there are some circumstances where it might meet the 4R criteria.  Fall nitrogen applied late in the fall when there is little likelihood of nitrification taking place might be ok as long as nitrification inhibitors are used as well.  This year, suppliers were as restrained in that regard as I have ever seen.  I hope it keeps up.

Urea is a form of nitrogen that has the potential to go awry.  First, it should not be used in the fall.  Second, consider urease inhibitors.  Third, incorporate immediately. 

What makes nitrogen management even more difficult, when you apply, is seen as a time management issue as well.

The ideal would be to use the presidedress nitrogen test on corn and sidedress all your nitrogen.  Some say that timing and weather make this a dicey proposition.  Sampling technique is also critical to get accurate tests.  It is probably also a good idea to consider potential release of N from organic matter.

What about the "new" amino N test developed in Illinois?  So far the literature review of the technique gives mixed results at best.   Some say it gives them an idea of what to do, others say it does not correlate with response to N fertilization at all.  If it does work, we need more consistent results in order to make recommendations.

Some say split applications are good.  I think it may have some merit in low exchange soils, but why not put on all of your N at the time when you would have made the last application.  This will give the most bang for the buck.