Monday, November 13, 2006

Effect of Rice Straw Incorporation on 15-N Labeled Ammonium Nitrogen Uptake and Rice Growth.

Manoch Kongchum, Dept. of Agronomy & Environmental, 104 M.B. Sturgis Hall, 104 M.B. Sturgis Hall, Baton Rouge, LA 70803, United States of America, Ronald DeLaune, South Stadium Drive, Louisiana State University - Agronomy & Environmental Management, Louisiana State University, School of the Cost & Environment, Baton Rouge, LA 70803-7511, Wayne Hudnall, Plant & Soil Science, Lubbock, TX 79409, United States of America, and Patrick Bollich, Louisiana State University Rice Experiment Station, Central Research Station, 2310 Ben Hur Road, Baton Rouge, LA 70820.

A greenhouse experiment was conducted to determine the effect of added rice straw residue on growth and uptake of ammonium nitrogen by rice in Crowley silt loam soil (Typic Albaqualfs). Nitrogen fertilizer was applied as 15N labeled ammonium chloride (NH4Cl), which had 3% 15N abundance at the rate of 150 kg N ha-1.  Total nitrogen and 15N labeled in plant were determined at different plant growth stages and in the root and grain at the harvest.  The higher rice straw treatment rate had an adverse affect on plant growth from the first to sixth week. After six weeks, the high rice straw treatment had a positive effect on plant growth (P<0.05). 15N labeled ammonium nitrogen uptake by rice was significantly lower (P<0.05) in the high rice straw treatment than in the treatment of lower rice straw addition. Highest atom % 15N in plant was detected at the panicle initiation stage under both water management treatments (2.61 and 2.64 atom % in alternately flooded and drained, and continuously flooded treatment, respectively).  Plant dry weight in control treatment (without rice straw) was greater than that of the treatments amended with rice straw.  Greater plant growth was recorded under alternate