Ammonia Volatilization and Nitrogen Uptake for Conventional and Conservation Tilled Dry-Seeded, Delayed-Flood Rice
- Barney R. Griggs *a,
- Richard J. Normana,
- Charles E. Wilsonb and
- Nathan A. Slatonc
- a Dep. of Crop, Soil, and Environmental Sciences, 115 Plant Science Bldg., Univ. of Arkansas, Fayette, AR 72701
b Univ. of Arkansas, Rice Research and Extension Center, 2900 Hwy. 130 East, Stuttgart, AR 72160
c Dep. of Crop, Soil, and Environmental Sciences, 1366 W. Altheimer Dr., Fayetteville, AR 72704
In the southern U.S. dry-seeded, delayed-flood rice (Oryza sativa L.) culture system, there are two practices that can aggravate NH3 volatilization losses of urea applied preflood: untimely application of the permanent flood and conservation tillage. The objectives of this study were to determine the influence of tillage practice, N source, and application time on NH3 volatilization, N uptake, and grain yield of delayed flood rice grown on a clay and silt loam soil. Multisite field studies were conducted in 2000 and 2001 using both stale-seedbed and conventional tillage practices with urea and (NH4)2SO4 applied 14 d preflood and urea 1 d preflood at four N rates. Ammonia volatilization was measured and plant samples were collected for N uptake and grain yield. Ammonia volatilization was the highest (14–32%) and N uptake and grain yield of rice the lowest when urea was applied 14 d preflood. Ammonium sulfate applied 14 d preflood lost little N (1.5–7%) via NH3 volatilization and resulted in N uptake and grain yields of rice similar to urea applied 1 d preflood. The stale seedbed had no effect on NH3 volatilization of (NH4)2SO4 and only affected urea in 1 yr on the silt loam soil when weedy residue was greater and the two tillage systems still produced rice with similar N uptakes and grain yields. Ammonia volatilization was more rapid and greater when urea was applied to the silt loam than to the clay. Ammonia volatilization loss of urea was impacted the most from delaying the flood and not from conservation tillage.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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