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.
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Well- and moderately well-drained soils
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.
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Poorly- and somewhat poorly-drained soils
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.
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Previous weeks
| Well- and moderately well-drained soils | Poorly- and somewhat poorly-drained soils |
| May 12 (PDF) | May 12 (PDF) |
| May 18 (PDF) | May 18 (PDF) |
| May 25 (PDF) | May 25 (PDF) |
| June 1 (PDF) | June 1 (PDF) |
| June 8 (PDF) | June 8 (PDF) |
| June 15 (PDF) | June 15 (PDF) |
| June 22 (PDF) | June 22 (PDF) |
| June 29 (PDF) | June 29 (PDF) |
Archive
Nitrogen watch information through 2015 is archived for use and for reference.