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Fluid Journal : Fall 2016
4 The Fluid Journal Fall 2016 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 The fourth leaf and petiole down the main stem of the cotton plant were sampled and separated immediately. Petioles were sampled weekly for the first five weeks of bloom. The petiole sampling was scaled back to minimize the number of samples and no treatment differences were observed during the late bloom period in the previous two years. The plant tissue samples were sent to Water’s Agricultural Laboratories (Camilla, GA) for analysis. The petioles were analyzed for nitrate-N, phosphorus, potassium and sulfur. Nutrient concentrations in petioles were plotted against time. Leaf samples were collected during the first and fifth weeks of bloom only, and a complete nutrient analysis was conducted on the leaf tissue. Defoliation and quality Defoliation timing for cotton varies, depending on the growing season and development of the crop. The trials were defoliated when 50-60% of the bolls were opened. Seed cotton was harvested using two-row commercial cotton picker modified for small plot harvest. The center two rows of each plot were harvested and plot weights recorded. A one pound sub-sample of seed cotton was ginned on a 10-saw micro-gin to determine lint percentage. Seed cotton weights were multiplied by the lint percentage to calculate lint yields. Cotton lint was sent to the USDA cotton quality lab in Florence, SC for lint quality analysis. The lint was analyzed using a High Volume Instrument (HVI) to determine the fiber length (staple), strength, micronaire, color, and leaf (trash) grade. Statistical analysis The data set was separated into three separate datasets and analysis of variance (ANOVA), using PROC MIXED in SAS 9.3 to determine among treatments (SAS Institute, 2012). The first data set consisted of the different nutrient management systems tested at the 100% P and K rate based on soil test recommendations. The nutrient management systems were analyzed as single treatment factors in a randomized complete block design. The second data set was to determine the effect of P and K rate and placement on each of the measured dependent variables. The data set was analyzed as a 3 x 2 factorial treatment design in a randomized complete block design using ANOVA. Fig. 1: Picture of the strip-tillage fertilizer systems and shank to place fluid phosphorus and potassium fertilizers at 6, 9, and 12 inches below the soil surface during strip tillage. Fig. 2; Demonstration of fertilizer placement with two row strip-tillage implement showing the accuracy of fertilizer (blue dye) placement with the developed applicator.