When we invest in nitrogen for our crop, shouldn’t we want a report card on how it worked? We can get that — with the fall stalk nitrate test (FSNT).
Since a lot of corn has reached black layer, it’s now time to take FSNT tests. This test simply tells you if there was adequate nitrogen during the season. A total of 15 to 20 stalks should be collected for each sample.
The eight-inch stalk sample is taken from the lower portion of the stalk. The first cut is made 14 inches above the ground; the second cut is made six inches above the ground. Place the samples in a paper bag — not plastic — and keep the sample dry and cool. Get the sample to a lab as soon as practical.
This crop year, with our higher than normal rainfall, does create a little “different than normal” scenario. So, results probably need to be interpreted with a little common sense.
I still like sampling each year, monitoring changes over time, and even want to collect results from a unique year like this. I think you need multiple years of information to make good decisions for the future with this test due to annual rainfall variation; but the more you know, the better future decisions will be.
To see a discussion on this test, and the impacts of a year like this, check out the recent article on the topic by Iowa State University Agronomy Professor John Sawyer.