When these soils are saturated with water, bacteria break down nitrate, and the nitrogen is released into the atmosphere as nitrogen gas. Heavy and prolonged periods of rainfall can result in nitrogen losses severe enough to require additional nitrogen applications to correct the problem. All sources of nitrogen are considered equal in their ability to provide nitrogen to cotton. No one form or source of nitrogen is superior to another if all are applied correctly. Base choices on price, availability, and ease of application.
Solid urea requires special consideration when applications are made to cotton.
If dry urea is applied to the soil surface in hot, dry weather, the rate of nitrogen loss can be high unless it is incorporated into the soil by tillage, rainfall, or irrigation within 2-3 days. If urea is incorporated into the soil by any of these methods within 2-3 days, or if the temperature is less than 75 F, losses are minimal. When left on the soil surface during midsummer for 5-7 days, in the most severe cases 50 percent or more of the nitrogen within the urea can be lost. Losses of over 30 percent in these situations are more common. Some growers apply nitrogen in split applications.