Information from 2000 Missouri Rice Research Update, February 2001.

Preflood Nitrogen Sources on Rice

Alan Sheckell, Gene Stevens, Chris Moylan, Holly Wilson, and Keith Birmingham


This test was designed to evaluate N sources and application methods. Rice was planted at the Missouri rice farm at Glennonville. The 1999 results showed that fertilizers with mostly nitrate-N produced less rice than sources with ammonium or urea. In 2000, most liquid fertilizer produced greater yields than dry urea.


Urea has traditionally been used as the preflood N source by producers for many years. The use of alternate N sources has been discussed for the preflood application.

Materials and Methods

This test was drill seeded with Cypress on May the 08, 2000. There were six treatments replicated four times. They were UAN (32% solution), urea, an ammonium nitrate: urea 50:50 dry mix, and urea (20% solution). The treatments were applied by dry broadcast, flat fan nozzles, and straight stream spray nozzles. This was 90 lbs of N applied at preflood. The mid-season N was supplied from urea at a rate of 30lb at ½ IE and another 30lb at ½ IE + one week for a total of 150lbs of N.


In 1999 there was a 20 Bu/acre increase in yield when the nitrates were not used. In 2000, the dry ammonium nitrate: urea 50:50 mix was the high yielding treatment with the flat fan treatments yielding 2 bu/acre lower. While the UAN and Urea broadcast with flat fan nozzles had high yields, there was significant burn damage observed in the plots. Less burn was observed when a straight stream nozzle was used. In each case, the rice grew out of the burn.

Table 1. Effects of N sources on yields.

Fertilizer Material Application
Dry Urea (Check) Dry Broadcast 146
Urea (20%N)
Flat Fan Nozzles 154
Urea (20% N)
Straight Stream Nozzles 150
UAN (32% N)
Flat Fan Nozzles 154
UAN (32% N)
Straight Stream Nozzles 146
Urea: AM. Nitrate
Dry Mix 50:50
Dry Broadcast 156
Plots received 90 LB pre-flood nitrogen from the
treatment N source, mid-season N was supplied from
urea (30 LB ½ IE, 30 LB ½ IE + 1 week.) Cypress
was planted for this test


There is a slight advantage of applying UAN, or urea with flat fan nozzle over applying it with straight stream nozzles and the check. While these showed a higher yield than the urea application they do have disadvantages. UAN and Urea flat fan applications had significant burn damage on the plants. In some years this may cause the rice to have lower yields. Availability of urea may be a problem in 2001. This research shows that other N sources may be used as alternatives.

This experiment funded by the Missouri Rice Research and Merchandising Council.

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