In some areas of the Southeast, the use of Bt-containing crops has grown along with the popularity of no-till and other conservation-tillage practices. The combination of no-till and Bt corn may be reason enough for growers in the Southeast to look at fall nitrogen application.

Though the heavier soils of the Midwest aren’t a true comparison of growing corn there and in the upper Southeast, the use of fall nitrogen is becoming a standard practice in fields in which corn stalks are left standing.

Veteran Kansas State Agronomist Dave Mengel says,“There has been a lot of work over the years showing that adding 30-40 pounds of N will speed up the decay process. Ideally, this N is sprayed on in a UAN solution that gives more uniform coverage.

If a grower decides to add N to corn stalks, they should do it as soon as possible. The whole idea is to get N into the system so that microbes will tie it up and utilize it. So, in this situation you want the nitrogen to be lost — because that’s what gets the residue to break down quicker, Mengel explains.

“Back in the 1980s there was a big push to get nitrogen in a corn field to break down the residue. Back then we did a lot of deep tillage and by adding additional N farmers could get the stalks broken down quicker and get them out of the way and ready for fall or spring tillage.

“Now, no-till is so popular, and farmers just don’t think the same way about corn residue as they did back then. However, plenty of high yield producing farmers in Kansas, especially those who grow corn after corn, are getting a tremendous buildup of residue. Going back to some of the practices we did in the 1980s, specifically adding extra N to corn residue, can help solve that problem,” the Kansas State researcher contends.

Whether corn growers in the Southeast need to apply extra nitrogen to speed decay of standing corn stalks likely depends more on the variety of Bt-corn planted and the rotation crop that follows. If corn is following corn, the extra N is likely a good insurance policy against N loss from slow decaying varieties.

rroberson@farmpress.com