Nitrogen watch for 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 ‘danger areas’ that received 12 or more inches of rainfall from May 1 to July 4. These areas are likely to have N deficiency in fields that received all N preplant. If N deficiency symptoms are visible, rescue N should be applied. Average yield response to rescue N in six 2010 trials was 34 bushels/acre in areas with excessive rainfall. The greater the visible N stress, the larger the response.