Given the current economics of rice, you may be planning on not topdressing. If there is enough N up front as aqua, this should be fine. The question is how to determine if you have enough. One easy, practical way to confirm that you do not need a topdress is to set up a small overfertilized area. To do this, apply about 1 cup of urea to a 10x10 ft area in your field. Avoid skips or overlaps. Mark it with flags or stakes so you can go back and check it. Do it within the first 30 days of seeding. Once you are nearing PI, about 40-45 days after seeding, go back and take a look. If you do not notice a difference between the overfertilzed area and the rest of the field, you do not need a topdress. If you can tell a difference, you may need a topdress. You can use the color chart, chlorophyll meter, or leaf tissue analysis to determine the N status of the field and decide if the topdress is really needed (see pages 6.8-6.9 in the Rice Production Manual).
