|
|
|
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 Fertilizer Source, Application Rate, and Timing on Grain Yields of Rice, 2002
Many rice farmers have a difficult time getting drill-seeded fields flooded in less than 5 to 10 days after the pre-flood nitrogen (N) application. This study was conducted to determine if ammonium sulfate (AS) is a better N source than urea (U) when applied onto the soil surface a week or more prior to flooding. Rice was grown on a Calloway silt loam (pH 7.3 to 8.3) to compare U and AS at five fertilizer rates (0, 60, 90, 120, and 150 lb of N/A) applied at four different timings: all pre-flood N either 21, 14, or 7 days before flooding, or one day prior to flooding.
The 2001 results coupled with results from 1999 and 2000 showed that if a farmer can not flood a field in a timely manner (less than 14 days) after the pre-flood N application, it would be prudent to use AS in place of U, even if at times the N fertilizer application has to be increased by 30 lb N/A, because it takes too long to establish a flood. Work was continued in 2002 using U, Agrotain®, AS, AS + U, and AS + Agrotain® at three N rates (0, 60, and 120 lb/A), at three times: 10, 5, or one day before flooding. Ammonia volatilization was measured for the sources at the 120 lb N/A rate and ranged from 0 to 25% of the applied N. Volatilization losses were greatest with U, while Agrotain®, AS, and AS + Agrotain® had the highest grain yields and least ammonia volatilized when N was applied 5 to 10 days before flooding. AR-18F
|
|
