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Fluid Journal : Fluid Journal 2005-2007
WINTER 2007 Fluid Journal 17 DR. GYLES RANDALL AND JEFF VETSCH Historically, starter fertilizers have not commonly been recommended for corn production on high or very high P-testing soils due to poor yield responses, even though early growth responses may be seen. However, renewed interest in starter (band-placed) fertilizer has increased as corn yields continue to increase, tillage intensity tends to decrease, and corn planting becomes earlier. With this renewed interest, questions have been raised regarding the inclusion of potassium (K) and sulfur (S) in the fluid starter in optimum positions 2 inches from the seed or as bands dribbled on the soil surface. Thus, the objectives of this research were: • Determine effect of various combinations and rates of NPKS as fluid starters for improving corn production and profitability on high P- and K-testing soils • Evaluate starter placement positions for NPKS fluid fertilizers for corn grown on high P- and K- testing soils • Provide management guidelines on fluid starter fertilizer rates and placements for corn grown on high P- and K-testing soils with reduced tillage. Concentration Concentrations of NPKS in the whole small plant at the V7 stage were inconsistently affected by the NPKS treatments. This was particularly true for N where statistically significant differences were found, but there was no clear What Is Optimum Placement of NPKS Starters for Corn on High-Testing Soils? Minnesota researchers seek answers as they conduct corn studies at research center in Waseca, Minnesota. SUMMARY Corn plant populations were not affected by any of the starter treatments except the 6+20+6+4 in-furrow, popup treatment, which reduced the population by 30 percent. Concentrations of NPK at the V7 growth stage generally were not affected by the starter treatments. Uptake of NPKS at the V7 stage was affected by the starter treatments due to large effects of the treatments on dry matter production. Dry matter was increased over the control by all starter treatments. With the exception of the 21-bu/A decrease in corn grain yield with the 6+20+6+4 popup treatment, grain yield and moisture content were not affected by the starter treatments. In summary, profitability was not improved this year on this very high P-testing soil by any of the starter NPKS rates or placement positions despite very significant and profitable responses on the same soil the preceding year. effect of rate or placement, and no interaction between rate and placement. Whole plant P and K concentrations were not affected by the starter P and K treatments. Whole plant S concentration was increased by the 2x0 and 2x2 treatments that received S. Concentrations of NPKS were similar between the 2x0 and 2X2 placement positions. Dry matter Dry matter accumulation at V7 was greatly affected by the starter P treatments on this very high P- testing soil (Table 1). Dry matter was increased over the control by all starter treatments. Largest plants were obtained with the 6+20+6+4 and 6+20+0+0 popup treatments. Dry matter accumulation was similar for the 2x0 and 2x2 placement positions. Uptake These early growth differences resulted in highly significant differences in NPKS uptake among treatments. In general, greatest NPKS uptake occurred with the popup treatments and the 20+20+10+10 (2x2) treatment. Placement position (2x0 vs. 2x2) had no effect on NPKS uptake. Both were effective. Grain yield Grain yield was not increased on this very high P-testing soil over the no-starter control by any of the starter treatments (Table 2). However, the 6+20+6+4 treatment
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