Nitrogen watch for poorly- and somewhat poorly-drained soils


total precipitation Midwest

credit for MRCC maps

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.