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Integrated Pest & Crop Management


John A. Lory
University of Missouri
Plant Science & Technology
(573) 884-7815

The Missouri Corn Stalk Nitrate Test Challenge - 2011

John A. Lory
University of Missouri
(573) 884-7815

Published: August 1, 2011

For the third year MU Soil Testing Lab and I will be teaming together to run the Missouri Corn Stalk Nitrate Test Challenge. We will analyze up to 10 samples at the MU lab from any Missouri farm at no cost if you submit the requested information when you submit samples (see data form on page 135). Consultants can submit more than 10 samples as long it is clear that no more than 10 samples come from one farmer. Typical analysis cost for the test is $12 per sample. This free offer is available to the first 500 samples submitted to the lab; visit http:nmplanner.missouri.edu to see if we are still accepting samples under this program.

The Stalk Nitrate Test is a powerful tool to assess how well you managed nitrogen in your corn crop this year. Research from Iowa and other states has calibrated nitrate concentration in the corn stalk with the nitrogen status of the harvested corn crop. Corn stalks with a nitrate-nitrogen concentration between 700 and 2000 parts per million are in the optimal range. Nitrate concentrations above 2000 parts per million are indicative of a crop that had excess nitrogen; nitrate concentrations below 700 parts per million are indicative of plants that had marginal nitrogen supply (250-700 parts per million) or were clearly nitrogen deficient (greater than 250 parts per million).

  • The window of opportunity for collecting samples is from ΒΌ milk stage to up to three weeks after black layer formation. Corn stalks that have weathered heavy rain events well past black layer formation will yield incorrect results.
  • Use a set of hand shears or loppers to remove an eight-inch segment of corn stalk from the corn plant. The top cut should be 14 inches above the ground; the bottom cut six inches above the ground.
  • Get a stalk segment from at least 15 randomly selected plants from the field or subfield you are sampling. Do not sample diseased or damaged plants.
  • Place the samples in a paper bag for shipping to the lab for analysis. Do not freeze the sample. Samples held more than 24 hours before shipping should be refrigerated.

Send samples to: Attention Stalk Nitrate Test Challenge, 23 Mumford Hall, University of Missouri Soil Testing Lab, Columbia, MO 65211.
Visit the Corn Stalk Nitrate Challenge website at http://nmplanner.missouri.edu/tools/Stalk_Nitrate_Challenge.asp for more information and to download more copies of the reporting form.

What do we do with the collected data?
The primary use of the stalk nitrate test is to give you a post-mortem analysis of how well you managed nitrogen on your corn crop. When we combine your data with information from many different Missouri farms we can get an idea of how efficiently Missouri farmers are using fertilizer nitrogen on corn.

We remove farmer identity information on the sample data form and compile data from all submitted samples into a database. Ultimately we would like to collect this type of data for multiple years from hundreds of Missouri farms so we can demonstrate how efficiently Missouri farmers use fertilizer nitrogen. The Missouri Stalk Nitrate Challenge is hopefully a precursor to a larger voluntary statewide program.

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REVISED: September 28, 2011