Minnesota Research on Nitrogen Inhibitors

Nebraska soil temperature map
Maps of one-day and the weekly average soil temperatures are updated daily by Nebraska Mesonet and featured in the CropWatch Weather section.

Minnesota Research on Nitrogen Inhibitors October 20, 2017

As temperatures start to cool, growers may be considering a fall nitrogen application.

Are inhibitors beneficial with fall N applications? Research from the University of Minnesota shows that nitrification inhibitors can protect fall nitrogen against loss and increase the amount of nitrogen present in the ammonium form the following spring, as long as best practices are followed.

Read more about their findings in an article from this week's Minnesota Crop News.

While putting N on close to when the crop needs it is the ideal, other management strategies, such as including inhibitors and using slow release products, can help approximate this timing. For more on Nebraska nitrogen recommendations see Fertilizer Suggstions for Corn.

Soil temperature at most Nebraska sites reported in CropWatch are still above 50° F (Figure 1), usually used as the threshold for nitrogen applications.

Another University of Minnesota article notes: "Nitrifying bacteria are active until soils freeze at 32° F, but their activity is greatly reduced once soil temperature goes below 50° F. The 50° F rule is a good compromise between when the activity of nitrifying bacteria is low enough and there is still enough time for nitrogen applications before soils become too wet or frozen. The cooler the temperature the greater the efficiency of an inhibitor and the greater chance ammonium does not convert to nitrate."

Access daily and weekly average soil temperatures for Nebraska, as provided by Nebraska Mesonet, at https://cropwatch.unl.edu/cropwatchsoiltemperature.