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Fluid Journal : Fluid Journal 2002-2004
3 Fluid Journal Winter 2002 increase needed to cover all added costs of using starter based on the cost of the fertilizer and the price of cotton. This illustration assumes no price premiums or discounts for fiber quality. Breakeven yield increase includes fertil- izer, labor, fuel, equipment, warehous- ing, picking, hauling, and interest costs. Depending on the cost/price relation- ship, the breakeven yield increase ranges from 11 to 44 lbs/A. Mean yield differences observed in this study were mostly breakeven levels, but, as noted, many of the treatments were not statisti- cally different from the untreated check. Plant analysis Uptake. At Tifton in 1997 and 1998, side-banded UAN (32-0-0 and 28-0-0-5S) increased whole-plant N concentration at approximately five weeks after plant- ing relative to the untreated check and side-banded APP. In all studies, how- ever, whole-plant N concentration was never below the sufficiency range. Side-banded calcium nitrate (9-0-0- 11Ca) increased whole-plant Ca concen- tration over the APP starter at five weeks after planting at Tifton in 1998. At Plains in 1998, calcium nitrate (9-0-0- 11Ca) and 28-0-0-5S resulted in in- creased whole-plant Ca concentration at four weeks after planting relative to the APP starter. Whole-plant Ca was never deficient in any study or starter treat- ment. Plant height. Increased plant height was observed in only two of the six studies, once on the Tifton loamy sand and once on the Greenville sandy loam. In both instances, the increase could be attributed to side-banded APP. Dr. Bednarz is assistant professor of crop physiology at the Coastal Plain Experiment Station, U of Georgia; Dr. Harris is associate professor and extension soil fertility specialist and Dr. Shurley is professor and agricul- tural economist at the Rural Develop- ment Center, U of Georgia.
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