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Fluid Journal : Fall 2016
3 The Fluid Journal Fall 2016 (Figure 1). The broadcast P and K were applied on the same day as the strip tillage cultivation and deep placement of P and K for both locations. Diammonium phosphate (DAP) (18-46-0) and muriate of potash (0-0-60) were used as the P and K sources for the broadcast agronomic control treatment. The fluid phosphorus source applied was ammonium polyphosphate (10-34-0) (APP) and the fluid potassium source was potassium thiosulfate (0-0-25-17S). The potassium thiosulfate supplied 40.8 lbs sulfur (S)/A when applied at the 150% rate, which is greater than the recommended agronomic S rates in cotton for Virginia. Ammonium thiosulphate (12-0-0-26S) (ATS) was used to balance the S rate among treatments. In the treatments where a combination of placement techniques were implemented, the balance of S was applied using deep placement to prevent any potential injury to cotton seedlings. Preplant nitrogen (N) was balanced at the same level as the broadcast agronomic control plus additional N from ATS. The preplant N rate for the P and K fertilized treatments was 35 lbs. N/A. The N was balanced using urea- ammonium nitrate fluids (30-0-0). The total N application rate was set at 115 lbs N/A with the remaining 80 lbs. N being applied in a sidedress application using a 24-0-0-3S at TAREC and UAN30 at Lewiston applied at matchhead square. Other nutrients were applied based on the soil test recommendations. Development/sampling Plant population was measured by counting the number of emerged seedlings in two ten-foot sections of row. Plant population counts were taken at 7,10, 14, and 21 days after planting. Plant heights were measured weekly beginning with the appearance of the second true leaf and measured from the ground to the apical meristem on five randomly selected cotton plants per plot. Plant height and total node measurements ceased with the appearance of the first white flower at each location. During the bloom period, nodes above white flower (NAWF) were counted on five randomly selected plants per plot until NAWF ≤ 3. Beginning during the first week of bloom, twenty-four cotton petioles were sampled from the first and fourth rows of each plot. Table 1: Mehlich I extractable phosphorus and potassium at 0-3, 3-6, 6-9, 9-12 inch depths at TAREC and Lewiston Depth TAREC Lewiston inches P K P K ppm 0-3 46 (H+)¶ 80 (M+) 21 (H-) 81 (M+) 3-6 50 (H+) 83 (M+) 19 (H-) 58 (M) 6-9 35 (H) 66 (M) 13 (M) 43 (M-) 9-12 25 (H-) 59 (M) 8 (M-) 44 (M-) ¶ Indicates the soil test level based on Virginia’s soil test calibration Table 2: Strip-tillage, planting, and harvesting dates for all locations during the 2014 growing season Location Strip-tillage Planted Harvested TAREC 5/4 5/18 11/4 Lewiston 5/19 5/27 11/24 Table 3: Treatment List for 2014 Locations Trt Placement Description 1 Unfertilized Control No P or K Fertilization 2 Broadcast Agronomic Control P + K Broadcast – Soil test recommendation‡ 3 Starter Agronomic Control 100 lbs /acre† of 10-34-0 in 2X2 band + Remaining P+K broadcast 4 2X2 Band 50%P + 50%K¶ 5 2X2 Band 100%P + 100%K 6 2X2 Band 150%P + 150%K 7 Deep Placement 50%P + 50%K 8 Deep Placement 100%P + 100%K 9 Deep Placement 150%P + 150%K 10 2X2 + Deep Placement (80%P + 80% K) + (20%P + 20%K) 11 2X2 + Deep Placement (60%P + 60% K) + (40%P + 40%K) 12 2X2 + Deep Placement (40%P + 40% K) + (60%P + 60%K) 13 2X2 + Deep Placement (20%P + 20% K) + (80%P + 80%K) † 100 lbs/acre of 10-34-0 is the recommended rate for cotton placed in a 2X2 band at plant- ing in by North Carolina State University Cooperative Extension. ‡ Recommended nutrient application rates applied based on Mehlich 1 extractable phospho- rus and potassium and Virginia Cooperative Extension Recommendations ¶ Percentages represent the proportion of recommended nutrient application rates applied based on Mehlich 1 extractable phosphorus and potassium and Virginia Cooperative Exten- sion Recommendations. Table 4: Early season plant height of cotton grown under different nutrient manage- ment systems at TAREC Nutrient Systems Plant Height 3rdǂ 4th 5th 6th 7th 8th ---------------------------- in. --------------------------- Unfertilized Control 4.3b* 7.8b 13.5c 19.5c 24.3b 26.4b Broadcast Agronomic Control 4.6ab 7.7b 14.9bc 21.5b 28.1a 32.8a Liquid Starter Control 5.0 a 9.2a 17.1a 24.1a 29.7a 34.9a 100% 2X2 N-P-K-S 4.4 b 7.6b 14.6bc 21.8b 27.8a 32.8a 100% Deep Placement N-P-K-S 4.4 b 8.0ab 15.2b 22.5ab 29.1a 33.1a *Values with the same letter are not significantly different at α=0.05 ǂ Week after Planting