The Missouri Corn Stalk Nitrate Test Challenge

Published: August 17, 2010

For the second year MU Soil Testing Lab and I will be teaming together to run the Missouri Corn Stalk Nitrate 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. Typical analysis cost for the test is $12 per sample.

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. 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 (<250 parts per million).

How to sample fields

• The window of opportunity for collecting samples is from ¼ milk stage to up to three weeks after black layer formation.
• 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.
• 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 or MU Delta Regional Soil Testing Lab, 147 State Hwy T, Portageville. MO 63873.

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.