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Fluid Journal : Fluid Journal 2008-2009
to applied S in two out of three years. Because of the specific treatments used, it was not possible to estimate apparent NUE. However, N removal in the forage was significantly increased when S was included in the fertility package, indicating higher NUE with S addition. Spacing Finally, there is the question of surface band spacing. What spacing is too wide? Is narrow spacing better? Some Texas research, evaluating surface band spacing on bermudagrass from 7 through 28 inches (Table 2), measured very little effect of spacing on yield, quality, or NUE. However, significant "streaking," owing to N deficiency between the 28-inch bands after N application, was noted but became less visually apparent with time. The researchers concluded that the 28-inch band spacing was too wide for these production systems. Based on earlier NP research for winter wheat and past observations, some suggest that a spacing of 10 to 15 inches would likely be optimum with the potential for streaking at a wider spacing being greater for later applications and when P is included in the fertility program. While narrower spacing reduces the potential for streaking, very narrow spacing would gradually begin to resemble broadcasting in terms of fertilizer distribution. Dr. Leikam is President of the Fluid Fertilizer Foundation. Table 2. Effect of dribble band spacing on bermudagrass production Haby et al., Texas A&M -- 3-year average Dribble Band Spacing Bermudagrass Yield Forage N Apparent NUE Lbs/A % % 7 inches 14945 1.53 56.1 14 inches 14506 1.75 64.9 21 inches 14814 1.67 62.6 28 inches 14470 1.74 65.1 18,000 16,000 14,000 12,000 10,000 8,000 6,000 Year 1 Year 2 Year 3 UAN UAN + ATS Figure 3. UAN vs. UAN + ATS in yield trials on bermudagrass, 3-year average, University of Georgia.
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