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Fluid Journal : Fluid Journal 2005-2007
Early Spring 2006 Fluid Journal 2 conditions. The advent of earlier planting has also ushered in a renewed interest in starter (bandplaced) fertilizer. Subsequent questions have been raised regarding the inclusion of potassium (K) and sulfur (S) in the fluid starter as well as what constitutes optimal starter placement (in-row with seed versus bands two inches from the seed or bands dribbled on the soil's surface?). To try to answer these questions, a study was developed and conducted in 2004 with the following objectives: • Determine the effect of various combinations of NPKS rates as starter fertilizers for improving corn production and profitability on high P- and K-testing soils • Evaluate placement positions for NPKS fluid starters for corn grown on high P- and K-testing soils • Provide management guidelines to corn producers, crop advisors, and the fertilizer industry on fluid starter fertilizer rates and placements for reduced-till corn grown on high P- and K-testing soils. Concentration Concentrations of NPKS in the whole plant at the V6 stage were inconsistently affected by the NPKS treatments (Table 1). This was particularly true for N and K where statistically significant differences were found, but there was no clear rate or placement effect and no interaction between rate and placement. Whole plant P concentration was greatest (0.423%) when the starter P was placed in the seed furrow and least (0.386%) when placed on the soil's surface. Whole plant S concentration was not affected by any of the treatments. Concentrations of NPKS were similar between 2-inch x 0 and 2- inch x 2-inch placement positions. Dry matter Dry matter accumulation at V6 was greatly affected by the starter P treatments on this very high P-testing soil (Table 2). Dry matter was increased over the control by all starter treatments exceptthe20+20+6+0treatment dribbled on the soil's surface. Largest plants were obtained with the 6 + 20 + 6 + 4 pop-up treatment. Starter fertilizer with sulfur (S) produced greater early plant growth than when S was omitted. These early growth differences resulted in highly significant differences in NPKS uptake among treatments. In general, greatest NPKS uptake occurred withthe6+20+6+4pop-uptreatment andthe40+40+10+10treatment dribbled on the surface. Placement position (2-inch x 0 vs. 2-inch x 2-inch) had no effect on NPKS uptake. Grain yield Grain yield was increased on this very high P-testing soil over the no- starter control by all starter treatments except the 20+ 20 + 6 + 0 treatment dribbled on the soil's surface (Table 3). A 17.1 bu/A response was obtained with the 6 + 20 + 6 + 4 pop-up treatment. Rate/A Placement Sources Yield lbs/A 0+0+0+0 None None 134 6+20+6+4 Pop-up APP + KTS 316 20+20+6+4 2x0 APP+UAN+KTS 200 20+20+6+4 2x2 APP+UAN+KTS 196 20+20+0+4 2x0 APP+UAN+KTS 182 20+20+0+4 2x2 APP+UAN+KTS 200 20+20+6+0 2x0 UAN + 7-21-7 156 20+20+6+0 2x2 UAN + 7-21-7 178 20+20+10+10 2x0 APP+UAN+KTS+ATS 218 20+20+10+10 2x2 APP+UAN+KTS+ATS 192 20+40+10+10 2x0 APP+UAN+KTS+ATS 228 40+40+10+10 2x0 APP+UAN+KTS+ATS 284 Table 2. Dry matter accumulation of NPKS in whole small corn plant (V6) at Waseca, 2004. Rate/A Placement Sources Yield Moisture bu/A % 0+0+0+0 None None 181.7 27.3 6+20+6+4 Pop-up APP + KTS 198.8 22.7 20+20+6+4 2x0 APP+UAN+KTS 198.9 24.1 20+20+6+4 2x2 APP+UAN+KTS 195.6 24.6 20+20+0+4 2x0 APP+UAN+KTS 197.4 25.0 20+20+0+4 2x2 APP+UAN+KTS 198.5 27.0 20+20+6+0 2x0 UAN + 7-21-7 186.8 28.1 20+20+6+0 2x2 UAN + 7-21-7 196.2 26.7 20+20+10+10 2x0 APP+UAN+KTS+ATS 210.2 24.3 20+20+10+10 2x2 APP+UAN+KTS+ATS 202.4 25.1 20+40+10+10 2x0 APP+UAN+KTS+ATS 200.8 25.3 40+40+10+10 2x0 APP+UAN+KTS+ATS 202.4 23.6 Table 3. Grain yield and grain moisture as influenced by NPKS rate, placement, and source at Waseca, 2004.
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