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Fluid Journal : Fluid Journal 1996-1998
3 Fluid Journal Fall 1998 0 20 40 60 80 100 120 160 Yield - bu/A Henrico County New Kent County S-lbs./A- 15 30 45 Figure 3. Grain yield response to variable rate preplant broadcast of P2O5, N starter constant at 40 lbs/A, Henrico and New Kent counties, Khosla, et al., 1997. Figure 4. Grain yield response to variable rate preplant application of sulfur, N starter constant at 40 lbs/A, Henrico and New Kent counties, Khosla, et al., 1997. 0 20 60 80 100 120 140 160 Yield - bu/A Henrico County New Kent County PO-lbs./A 25 - 20 40 60 high. Lack of sorghum response to phosphorus fertilization confirmed that the calibrations were correct. Previous application of ammonium sulfate and release of S from soil organic matter and crop residues apparently provided sufficient levels of sulfur for grain sorghum growth under these conditions. S po ntil hows pote ia Shows potential Shows potential Shows potential Grain sorghum performed fairly well under both normal and subnormal rainfall to demonstrate its acceptability as an alternative to corn. A grain yield level of 71 bu/A in extremely dry years, as reported in this study, to 160 bu/A in a good rainfall year like 1996 is encouraging. Research has shown it has a much higher yield potential under drought conditions than corn. Incorporation of soil profile mineral N as an integral part of the fertilizer N recommendation system would increase N-use efficiency and profitability, and enhance environmental quality. Residual mineral N does contribute to crop yields in these humid-region soils. This concept has not been readily accepted and used. S lte frst oi testfi s Soil test first Soil test first Soil test first High levels of P and adequate levels of S already in the soil dampened any crop response to applications of these two nutrients. Soil sampling, therefore, using surface sample testing for P and deep samples for nitrates and sulfur, offers a means to improve fertilizer-use efficiency in grain sorghum production. Methodolo Mthdogy Methodology Methodology Methodology Location. Field experiments were conducted during the summer of 1997 in the Central Coastal region of Virginia. Soils were an Atlee very fine sandy loam (fine-loamy, mixed, thermic Typic Fragiudults) and Kempsville fine loamy sand (fine-loamy siliceous, thermic Typic Hapludults). These soils have less than 3 percent slopes and are typical of those widely used for grain sorghum production in Virginia.
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