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.
The decision to use split applications, as opposed to all pre-plant, should be based on the rate of nitrogen used and whether or not irrigation is possible. If you will use more than 100 pounds nitrogen per acre, you should split the rate because of the danger of salt damage. Daily use rates of nitrogen are relatively low until squaring. Split applications of nitrogen tend to increase the chances of providing nitrogen to meet crop demands during peak demand periods. This late application would have to be aerially applied and must be done only where irrigation is used.