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Fluid Journal : Fluid Journal 2005-2007
EARLY SPRING 2007 Fluid Journal 19 Figure 3. Foliar B effect on soybean yield at the Western Ohio Research Center, 1991-92. Foliar B at 0.25 lb/A (2-week intervals) at R-1 through 1 lb/A rate, 3 lbs B/A applied preplant. Figure 2. Foliar B effect on soybean yield at University of Illinois experiment stations at DeKalb and Monmouth, 1991. Foliar B at 0.25 lb/A (2-week intervals) at R-1 thru 1 lb/A rate, 3 lbs B/A applied preplant. Boron Cultivar lbs/A ABCDE Yield bu/A 0 5935465240 0.256641595546 0.506140535543 1.006439655958 Cultivars: A: Braxton, B: Delta Pine, C: NK Coker, D: NK Coker E: Pioneer. Check 0.25 0.50 1.00 3.0 lbs/A B DeKalb Monmouth Yield bu/A 45 40 35 30 25 20 15 hours. There should also be no worry about pesticides breaking down once they are on the crop. Solution pH is decreased as the plant leaves absorb hydroxyl ions into the leaf apoplast at the cellular level where pH is buffered between 5.5 and 6.5. Buffer. Inclusion of an appropriate buffer to control the pH of tank mixes is suggested for those pesticides whose efficacy is known to be reduced with increased pH. Jar test. The multitude of pesticide-fertilizer-adjuvant tank mixes currently recommended for crop management requires that the applicator always conduct a preliminary "jar test" and always be sure that the spray equipment provides proper agitation of mixtures. Evidence of response Figure 1 shows B deficient soybean pods in a 2003 study conducted by Dr. Nathan Slaton, University of Arkansas. Soil on this study site was an alkaline silt loam where B deficiency was severe. Yield responses to foliar B were reported to be as high as 19 bu/A. Soybean yield increases of this magnitude can be expected on extremely low B soils where plants show visual deficiencies. However, equally substantial increases in yield have been found where no visual deficiencies existed. Other sites in Illinois, Ohio, and Georgia, demonstrating responses to foliar B, are shown in Figures 2, 3 and Table 1. Deter mining need Plant tissue analysis can determine if B is low in soybean plants. Normally, B is suggested where tissue B falls below 20 ppm in the top mature leaves before bloom. However, recent data suggest that additional response to foliar B may occur if leaf tissue is below 40 ppm B. Soil analysis interpretation varies with soil type. In coarse-textured soils, B at 0.4 lb/A may be sufficient, while greater than 1 lb/A may be needed in finer-textured soils. For intensively managed high-yield soybeans, especially under irrigated conditions, B should be applied to ensure that this essential element will not be a limiting factor. Dr.Woodruff is an ag consultant with U.S. Borax. Yield bu/A 65 60 55 50 45 40 35 Check 0.25 0.50 1.00 3.0 lbs/A B
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