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Fluid Journal : Fluid Journal 1996-1998
1 Fluid Journal Spring 1997 Summary: High economic yields were obtained at the Virginia Tech Tidewater Agricultural Center in Suffolk, Virginia, using drip/trickle tubing buried with 3-foot tube spacing below the soil surface of each row. The addition of boron also proved to be a critical element in Virginia sandy loam soils that are boron deficient. With better nutrient management (P K, Ca, B, Mg), projections show yields of 225- 280 bu/A corn, 60-80 bu/A soybeans, 1,200-1,700 lbs/A cotton, and 5,000- 7,000 lbs/A peanuts can be commercially obtained on a sustained basis with subsurface drip irrigation (SDI). Dr. Norris L. Powell Subsurface Drip System Fine Tunes Nutrient Management For High Yields Virginia researcher also shows the importance of monitoring soil makeup and moisture in attaining high yields. was 67 to 95 percent of normal. The drop was attributed to increased disease pressure within the plant canopy because of added water. Sclerotinia blight was not controllable with chemicals. Thus, this foliar disease was able to thrive in the moist soil and plant canopy, causing considerable loss. From this it became apparent that water management was a limiting factor for high-yield crop production. When irrigating, we further concluded water needed to be applied below the soil surface in the crop root zone where its use is most efficient. Soil is another factor we had to consider in the equation. Our native soils (uncultivated, unfertilized, and unlimed) are low in fertility, organic matter, and pH. Our Emporia fine sandy loam is a good example. This soil, with low CEC because of its coarse texture and kaolinic 1:1 clays, is low in organic matter, pH, P, K, Ca, and Mg in the top three horizons where most of the crop Briefly, some background onhow we began our journey toward high economic yields. Over the last decade, dryland corn production on the coarse-textured soils of the coastal plains of Virginia,has averaged from 50 to 177 bu/A, depending on rainfall (Figure 1). Earlier irrigation research on corn and peanuts (1980 to 1983), using a hard hose tow traveling gun, showed that both crops were responsive to water during very dry years. During that period, corn averaged 102 bu/A dryland (ranging from 32 to 146 bu/A) compared to 178 bu/A irrigated (ranging from 167 to 199 bu/A). Peanut pod yield averaged 2,000 lbs/A dryland compared to 4,000 lbs/A irrigated (1980). However, irrigated peanut production fell below non-irrigated peanuts during the next three years when growing season rainfall. Briefly, some background on how we began our journey toward high economic yields. Over the last decade, dryland corn production on the coarse-textured soils of the coastal plains of Virginia, has root zone thrives. Readings of 2.6 percent organic matter levels found in the plow layer of this soil have been considered high, the most likely explanation for this anomaly being that Emporia fine sandy loam represents a forested soil. Most cultivated soils would have 0.5 to 1.5 percent organic matter in the plow layers. Once water becomes a non-limiting factor for crop production on these coarse-textured soils noted above, fertility will then be limiting. Boron low Through tests on an Emporia/Uchee soil (Table 1), we later discovered yet another critical element found to be low in these soils---boron. Studies show that 0.5 to 1.0 ppm is needed for adequate crop production. From an irrigated study of corn in 1983 and 1984, we found in 1983 that green leaf area index (GLAI) closely resembled predictions. However in
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