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Fluid Journal : Fluid Journal 2005-2007
18 Fluid Journal FALL 2007 mid-southern USA, optimum N fertilizer use efficiency has been achieved by applying at least 50 percent of the total N immediately prior to permanent flood (PF) establishment, and the remaining N during the interval between inter- node elongation (IE) and 10 days following IE of 0.5 inch, commonly known as midseason (MS). However, recent work in Arkansas has shown that some new rice cultivars produce yields that are comparable and sometimes greater, following a single PF application as opposed to a two- or three-way split of the total applied N. Limited research has been conducted for the practice of banding plant nutrients in a drill- seeded, delayed-flood rice culture. Preplant (PP) banding N on a clay soil in Texas has shown promise. The most commonly used N application strategies in Mississippi consist of three to five applications per season. Once rice reaches MS, N is topdressed either in one or two applications to supply 45 to 90 lbs/A. Most of the fertilizer is applied with an aircraft. Research has shown that to obtain optimum N efficiency, the PF application should be made to dry soil and the field flooded within 5 to 7 days. When fields take longer than 7 days to establish a permanent flood, N is more prone to loss via volatilization. More recently, Mississippi State University Extension Service economists are learning that banding fluid fertilizer can potentially reduce applications costs fivefold. Banding fluid fertilizer, they are discovering, could potentially provide growers with a more economical option to produce rice yields that are equal to or greater than the standard method of application, with less environmental risks. These factors deem this potential practice worth investigating. The objective of this research is to evaluate the potential Figure 1. Mean rice grain yield as affected by an interaction among N rate and source. 169 188 189 110 105 101 0 50 100 150 200 120 150 180 lb N/A bu/A Banded (fluid) Broadcast (dry) Table 1. Treatment number, N source, N rate, MS N rate, yield and net return after fertilizer and application costs. Treatment # Source Timing N Rate MS N Rate Yield Net Return lbs/A bu/A $/A 1 Fluid Planting 120 0 158 c $630 e 2 Granular Planting 120 0 105 def $414 fg 3 Fluid Planting 150 0 179 b $708 b-d 4 Granular Planting 150 0 99 ef $380 g 5 Fluid Planting 180 0 181 b $704 cd 6 Granular Planting 180 0 98f $366 g 7 Granular Preflood 120 46 189 ab $738 a-d 8 Fluid Preflood 150 0 188 ab $759 a-c 9 Fluid Planting 120 46 179 b $700 d 10 Granular Planting 120 46 115 d $437 f 11 Fluid Planting 150 46 197 a $764 a 12 Granular Planting 150 46 111 de $412 fg 13 Fluid Planting 180 46 198 a $761 ab 14 Granular Planting 180 46 104 def $372 g 15 Granular Preflood 150 0 195 a $768 a-b 16 Non-treated -- -- -- 66g $278 h Means in the same column followed by different letters are different at the P 0.05 confidence interval.
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