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Fluid Journal : Fluid Journal 2005-2007
Winter 2006 Fluids Shine in Rice Trials Dr. Fred Turner, Mike Jund, and Mark Hebert Summary: The combination of early flood (4-leaf stage) establishment and all-fluid-fertilizer (FF) applications during planting increased both nitrogen (N) uptake and rice yield in 2003. In 2004, early flood establishment effects were not significant. However, subsurface banding all-FF during planting continued to improve N uptake and rice yields. Calculated economic benefits of subsurface banded FF during planting compared to conventional 3-way split dry fertilizer treatments, ranged from $25 to $57/A and averaged $40/A. Texas studies show both the agronomic (yield) and economic advantages of fluid fertilizers. Fluid Journal 1 Current basic rice production practices in Texas, and most of the southern U.S., consist of drill planting rice in dry soil and establishing a 4-inch deep flood 25 to 30 days later when rice seedlings have approached the 6-leaf growth stage. The first fertilizer application is applied near planting, followed by at least two more aerial applications of nitrogen (N). Delaying flood establishment increases the amount and number of herbicide applications to control weeds. Delaying flood establishment (6-leaf stage) also increases the potential of N fertilizer loss through ammonia volatilization, nitrification, and denitrification. In the past, multiple aerial N applications improved N efficiency compared to one application. However, current aerial application cost of about $8/A, for applications of less than 110 lbs/A of urea, can be higher than the cost of N fertilizer on a per pound basis. It appears that the subsurface banding of all-FF at planting, coupled with earlier flood establishment, has potential to reduce rice production costs in three areas: fewer aerial herbicide applications, lower N application costs, and lower N rate through improved N uptake. The improved economics of rice production through early flood and subsurface banding of all-FF at planting assumes this combination of practices does not negatively affect rice yield. Therefore, our objective in this study was to compare all-FF (subsurface banded while planting) with conventionally applied dry fertilizer when flood irrigating at the 4- or 6-leaf stage. N uptake 2003. Table 1 shows that all-FF increased mid-season N uptake over that of dry urea from 82 to 103 lbs/A and from 66 to 93 lbs/A under the 4- and 6-leaf flood stages, respectively. Note that at the 4-leaf flood stage both fluid and dry showed improved N uptake versus the 6-leaf flood stage. 2004. Early fl ood establishment did not increase N uptake in 2004 possibly because of early-season rain on clay soil and high native N supply on the silt loam soil. Therefore, N uptake data in Table 1 are the average N uptake for the 4- and 6-leaf flood treatments on each soil. On the clay soil, N uptake for the all-FF treatment was 152 lbs/A or approximately 50 percent higher zutthan the three other N treatments, which averaged about 105 lbs/A of N uptake. On the silt loam soil, N uptake for the all-FF treatment was 142 lbs/A, which was on a par with that of the three-way split of dry fertilizer and higher than the dry fertilizer at planting. Yield 2003. Figure 1 shows that the non- fertilized rice plants yielded 2,100 and 1,500 lbs/A when flooded at the 4- and 6-leaf stages, respectively, suggesting
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