~This weeks blog is brought to you by Dwight Willoughby, P.Ag, CCSC~
Corn Stalk Nitrate Testing
More agronomists are using the “cornstalk nitrate test” late in the season to evaluate their “N” management. This tissue testing procedure was developed at Iowa State University to help evaluate nitrogen management practices in corn as the crop matures.
The research shows that when corn has not had enough nitrogen, the nitrate value in the lower portion of the cornstalk will be low. If too much nitrogen was applied, the nitrate level in the lower stalk will test high.
This test may be of particular interest to growers who deal with manure or those wishing to evaluate their nitrogen fertility program.
Corn Stalk Nitrate Test Interpretations / Ranges and indexes used to interpret shown below
Low: (Less than 250 ppm) Likely that nitrogen was deficient and limited yield
Marginal: (250 – 700 ppm) Possible that nitrogen deficiency limited yield
Optimal: (700 – 2000 ppm) Yield was not limited by nitrogen
Excess: (> 2000 ppm) Nitrogen supply was excessive
2016 Samples Results
Corn stalks were collected midway through harvest in a random pattern and shipped to Agvise North Dakota. Results were interesting, a couple fields were manure, others conventional programs and a couple top dressed. Plans are to continue this service for interested customers