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Interpretive Summaries:
2003 - Influence of Nitrogen Fertilizer Source, Application Rate and Timing on Grain Yields of Delayed- Flood Rice
2002 - Influence of Nitrogen Fertilizer Source, Application Rate, and Timing on Grain Yields of Rice
2001 - Influence of Nitrogen Fertilizer Source, Application Rate, and Timing on Grain Yields of Rice
2000 - Influence of Nitrogen Application Rate, Time, and Source on Rice Yields
1999 - Influence of Nitrogen Application Rate, Time and Source on Rice Yields
Influence of Nitrogen Application Rate, Time, and Source on Rice Yields, 2000
Drew rice was grown at Colt, Arkansas, on a Calloway silt loam (pH 7.3 to 8.3) to compare urea and ammonium sulfate [(NH4)2SO4] at five fertilizer N rates (0, 60, 90, 120, and 150 lb/A) applied at four different timings (all N 14 days before flooding, all N seven days before flooding, all N pre-flood the day of flooding, and half of the N pre-plant plus half pre-flood). There was a three-way interaction among N source, rate, and timing. When all the N was applied at pre-flood the day of flooding, there was no yield difference between N sources at any N rate. Yields (154 to 160 bu/A) did not increase from either source with this pre-flood timing at rates above 90 lb N/A. When either source was applied one week before flooding, 120 to 150 lb N/A were required to maximize grain yields. Ammonium sulfate was superior to urea if applied two weeks before flooding on this high pH soil, but required 120 to 150 lb N/A to achieve the same yield as 90 lb N/A of either urea or (NH4)2SO4 applied pre-flood, the day of flooding. If a farmer cannot flood a field within 10 to 14 days of N application, it would be prudent to use (NH4)2SO4 instead of urea on high pH soils. AR-18F
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