Nitrogen watch

This page tracks spring rainfall and identifies danger areas that are on track to have problems with nitrogen loss and deficiency in corn. This is a serious production and environmental problem that is estimated to cost Midwestern corn producers 2 billion bushels total from 2008 to 2011.

  • Well- and moderately well-drained soils

    well drained midwest July 1st

    Well-drained soils are vulnerable mainly to nitrogen loss from leaching. This process can start shortly after fertilizer application (with some delay for ammonia). We have used April 1 to represent a preplant N application date. For ammonia or for applications later than April 1, risk is lower; for applications before April 1, risk is higher.

    Areas shown in cross-hatch are ‘problem areas’ that have already received 16 or more inches of rainfall since April 1. I expect a majority of fields to have substantial yield loss due to N deficiency when all N was applied pre-plant. I suggest that producers look at their fields and when N stress is seen apply additional N. Rescue N applications are likely to be profitable until tasseling or later in fields with deficiency symptoms. Satellite images or canopy sensors potentially provide a way to improve distribution of this N application, putting more N where stress is greatest and little or none where corn looks good.

  • Poorly- and somewhat poorly-drained soils

    poorly drained midwest July 1st

    Poorly-drained soils lose N mainly by denitrification, which is very temperature-sensitive. My rule of thumb is that wet conditions in May and June cause denitrification losses, but losses in April are minimal.

    Areas shown in cross-hatch are ‘problem areas’ that have already received 12 or more inches of rainfall since May 1. I expect a majority of fields to have substantial yield loss due to N deficiency when all N was applied pre-plant. I suggest that producers look at their fields and when N stress is seen apply additional N. Rescue N applications are likely to be profitable until tasseling or later in fields with deficiency symptoms. Satellite images or canopy sensors potentially provide a way to improve distribution of this N application, putting more N where stress is greatest and little or none where corn looks good.


Thanks to the Midwest Regional Climate Center for the rainfall maps on which Nitrogen Watch is based.

Previous weeks


Well- and moderately well-drained soils

Poorly- and somewhat poorly-drained soils

June 23 (PDF) June 23 (PDF)
June 16 (PDF) June 16 (PDF)
June 10 (PDF) June 10 (PDF)
June 2 (PDF) June 2 (PDF)
May 26 (PDF) May 26 (PDF)
May 19 (PDF) May 19 (PDF)
May 12 (PDF) May 12 (PDF)
May 5 (PDF)

Archive

Nitrogen watch information through 2015 is archived for use and for reference.

Nitrogen watch archive