Fall-applied nitrogen at risk for N loss

COLUMBUS – Each year after soybean harvest, producers may consider applying nitrogen in the fall for next year’s corn crop.

There are two main advantages to this practice, says Ed Lentz, OSU Extension agronomy specialist.

First, nitrogen prices may be lower in the fall than the spring, and secondly, time and labor may be more available than spring.

The big disadvantage is the greater potential for nitrogen loss, he admits.

Yield impact. In some years this nitrogen loss may cause a yield reduction.

In an eight-year study, Ohio State University scientists showed that average corn yields were about 5 percent higher from spring-applied anhydrous compared to fall-applied at the 160 pounds of nitrogen per acre.

Without a nitrification inhibitor, the difference was almost 10 percent.

Some years this percentage may be less and others more, depending on the weather, Lentz said.

Use anhydrous. Since fall-applied nitrogen has to remain in the soil for about six to seven months, the university recommends only anhydrous ammonia plus a nitrification inhibitor as a nitrogen source.

As a further deterrent to nitrogen loss, they recommend applications after the soil temperature drops below 50º F and will remain below 50.

Warmer conditions will shorten the effectiveness of the nitrification inhibitor.

Apply fall nitrogen only on well-drained soils, Lentz added, and do not fall apply on sandy ground.

To read more. Additional information may be found in the publication: Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat & Alfalfa at your county extension office, or download from the Internet at http://ohioline.osu.edu/lines/farm.html and select the software option.