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Soil temps are key to applying N in fall

If this harvest is as late as many anticipate, the temptation to apply anhydrous ammonia too early will be nonexistent.

Just in case, University of Illinois fertilizer specialist Fabian Fernandez reminds folks of the proper fall-applied guidelines. Only apply anhydrous ammonia on soils with a maximum bare soil temperature of 50 degrees F (at 4 inches deep) — and that’s getting cooler.

Remember, the recommendation that anhydrous ammonia can be applied in 60-degree-F soils with the use of N-Serve has been removed from the U of I agronomy handbook. Even at 50 degrees F, Fernandez recommends using N-Serve.

Looking at temperature data from 1989 to 2007, central and northern Illinois soils typically reach the 50-degree mark in the first two weeks of November. On average, U of I’s DeKalb ag center reaches 50 degrees on Nov. 2. Champaign soils hit that mark on Nov. 12.

“We do not recommend fall application of anhydrous ammonia south of Illinois Route 16,” Fernandez adds.

Visit www.isws.illinois.edu/warm and click on “Soil Temperatures” on the left.

This article published in the September, 2011 edition of PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.