PREFLOOD NITROGEN TIME - ALREADY?

It’s only the first week of May and the earliest fields are now approaching time for preflood fertilizer. The rain can create some problems for growers as it becomes time for preflood fertilizer but we have experienced good drying conditions between rains so far this spring. Urea should be applied to rice onto dry soil prior to establishing the permanent flood. Agrotain should be used with the urea to reduce volatilization losses unless the field can be flooded in less than 2 days.

If the fields are wet when the preflood urea needs to be applied, the best option is to wait until the soil dries. A delay of up to 10 days after the last DD50 recommended date is better than applying the urea into muddy soil or directly into the floodwater. If it becomes necessary to apply the urea to muddy soil, apply Agrotain-treated urea to the soil and flood up as soon as possible. The least effective method of applying preflood nitrogen is directly into the flood, even if Agrotain is used. While several growers have made excellent rice by spoon-feeding into the flood, this is the least efficient method and generally requires more urea to maximize yields. The recommended fertilizer rates and timings for the most commonly available rice varieties in Arkansas are listed below.

These recommended rates are for rice following soybeans in rotation. For other rotations, consider the following:
1. Increase early N rate by 30 lbs/A if rice is grown on clay soils.
2. Increase early N rate by 20 lbs/A if:  i) rice follows RICE in rotation or ii) the stand density if < 10 plants per sq. ft.
3. Increase early N rate by 10 lbs/A if rice follows GRAIN SORGHUM, WHEAT, CORN, or COTTON in rotation
4. Decrease early N rate by 10 lbs/A if rice follows SETASIDE or FALLOW that is not continuously tilled in rotation
5. Omit early N rate if rice follows FISH, LONG-TERM PATURE, or FIRST YEAR AFTER CLEARING in rotation.

Management of preflood nitrogen is most important for determining overall yield potential.  If this application is not managed as well as possible, it is very difficult to make up for the mistake at midseason.