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Fluid Journal : Fall 2016
7 The Fluid Journal Fall 2016 as well. At TARAEC, the petiole P concentrations decreased from 2000 ppm P to 1,000 ppm P during the first five weeks of bloom at TARAEC where concentrations decreased from 1,700 ppm to 1,500 ppm during the same time period at Lewiston (Figures 3B and 4B). At TAREC, petiole K concentrations were significantly different for 3 out of 5 weeks of bloom with the unfertilized control having significantly lower petiole K concentrations than the fluid starter control during the 1st, 2nd, and 4th weeks of bloom (Figure 3C). During the 2nd and 4th weeks of bloom, the broadcast control produced significantly higher petiole K concentrations than the unfertilized control (Figure 3C). No differences in petiole K concentrations were observed at Lewiston. However, the unfertilized control had the lowest petiole K concentrations during each week of bloom (Figure 4 C). The last petiole nutrient evaluated was S and both locations had significant petiole S responses during bloom (Figures 3D and 4D). At TAREC, the unfertilized control had significantly lower petiole S concentrations during the first week of bloom than all other treatments and significantly lower than the broadcast control during the 2nd week of bloom (Figure 3D). At Lewiston, the 100% 2x2 N-P-K-S blend had significantly higher petiole S concentrations than the unfertilized control during the 1st, 3rd, and 4th weeks of bloom and was significantly higher than all fertilized treatments during the 3rd week of bloom (Figure 4D). The results at Lewiston indicated that placing S in a 2 x 2 band at planting was highly effective in supplying S throughout the growing season when 32% UAN was used as the sidedress N source. Whereas at TAREC, 24-0-0-3S UAN/ AMS fluid was used as the side-dress N source. During the 1st and 4th weeks of bloom, leaf tissue was sampled to determine differences among nutrient management systems and compared sensitivity of petiole and leaf nutrient concentrations when determining in- season nutritional status. At TAREC, leaf N for the unfertilized control was significantly lower than all fertilized Fig. 4: Nitrate-N (A), phosphorus (B), potassium (C), and sulfur (D) concentrations in cotton petioles using different nutrient application management systems during the 1st nine weeks of bloom at Lewiston, NC (*ANOVA was significant at α = 0.05 for that sampling interval). Table 10: Nitrogen, phosphorus, potassium, and sulfur concentrations in cotton leaf tissue during the 1st and 5th weeks of bloom at TAREC Nutrient Systems Leaf Nutrient Concentrations 1stǂ 5th N P K S N P K S --------------------------------------- % ---------------------------------------- Unfertilized Control 4.24 b 0.34 1.40 b 0.60 b 2.89 b 0.24 1.16 b 0.65 Broadcast Agronomic Control 5.15 a 0.35 1.69 a 0.97 a 3.62 a 0.25 1.44 a 0.82 Liquid Starter Control 5.19 a 0.36 1.64 ab 0.90 a 3.54 a 0.26 1.40 a 0.83 100% 2X2 N-P-K-S 5.21 a 0.35 1.51 ab 0.94 a 3.63 a 0.25 1.43 a 0.77 100% Deep Placement N-P-K-S 5.09 a 0.34 1.57 ab 0.92 a 3.62 a 0.24 1 .41 a 0.77 *Values with the same letter are not significantly different at α = 0.05 ǂ Week of bloom treatments (Table 10). The broadcast agronomic control had significantly higher leaf K concentrations than the unfertilized control during the 1st week of bloom and all nutrient management systems produced significantly higher leaf K concentrations than the unfertilized control (Table 10). The only other leaf tissue response at TAREC was during the 1st week of bloom for leaf S concentrations with the unfertilized control having significantly lower leaf S