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Fluid Journal : Fluid Journal 2002-2004
3 Fluid Journal Fall 2002 reduced by starters, especially at the late planting dates in no-till. Comparison of starter treatments indicated that yield benefits were maximized when starter contained N, P, and K (Figure 1). The same was true of grain moisture and plant height. Economic analysis of starter response data---which included consideration of yield effects, drying costs differentials created by grain moisture effects, and the cost of fertilizer applications--- indicated that the use of an NPK starter was profitable in 19 of 24 comparisons provided by these experiments. Observations showing large re- sponses to starter at late planting dates in no-till are consistent with results of Bullock et al. who reported that starters accelerated early plant growth and development as well as crop maturity at the end of the growing season. The beneficial effect of starter with the late no-till plantings was due to stimulation of early plant growth and development in an environment where late planting limited growth. The stimulation of early growth by the starter treatments allowed the crop to realize more of its yield potential by the end of the growing season. HIGH-TESTINGSOILS To address questions about the need for starters on high or excessively high testing soils, corn yield response to starters was evaluated on 100 on-farm trials over three years. Most of the sites selected had P and K soil tests in the excessively high range, and response to NPK starters applied 2 x 2 was measured relative to a no-starter control. State- wide, starters increased yields by about 4 bu/A in each year (Figure 2). At individual sites, yield response to starters ranged from --10 to +42 bu/A with a positive economic response to starters at 40 percent of the sites. Results show that profitable responses to starter can occur on soils with excessively high soil test levels for P and K. Dr. Bundy is professor and extension soil scientist in the Department of Soil Science, University of Wisconsin- Madison. Table 1. No-till corn yield response to starters in selected experiments, 1992-1999. Location Treatment Yield increase Missouri NPK,2x2 13 bu/A avg. (6 of 6 experiments) Iowa NPK,2x2 4to18bu/A (7 of 9 experiments) Wisconsin NPK,2x2 15 bu/A avg. (8 of 12 experiments) Illinois NPK,2x2 14 bu/A avg. (8 of 9 experiments)
Fluid Journal 1999-2001
Fluid Journal 2005-2007