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Fluid Journal : Summer 2015
11 The Fluid Journal Summer 2015 Table 4: In-season soil test characterization at Ottawa and Scandia sites. Soil parameters Ottawa Scandia Buffer pH 6.3 6.7 Mehlich P (ppm) 15.4 14.1 CEC (meq/100g) 22.3 22.9 OM (%) 2.93 2.69 K (ppm) 113.8 281.3 N03-N (24”) (ppm) 1.6 3.8 NH4-N (24”) (ppm) 6.3 9.5 Ca (ppm) 3232.3 2851.7 Mg (ppm) 514.8 465.5 S (ppm) 5.4 9.2 Zn (ppm) 1.3 0.7 Mn (ppm) 21.6 59.5 Fe (ppm) 112.6 111.4 Cu (ppm) 2.1 1.8 Table 5: Stand counts for each treatment combination at all sites, 2014 growing season. Treatments Rossville Ottawa Scandia -plants in 17.5-ft row length- 1 43.4 43.6 40.4 2 29.4 38.2 46.8 3 81.8 85.6 42.4 4 43.2 41.8 43.4 5 42.2 43.2 35.8 6 42.2 43.4 27 7 42.8 43 27.8 8 41.8 42.8 28.6 9 42.6 43.8 29 10 60.8 54.2 32.6 11 43.4 42.4 34.4 C.V. 3.49 12.32 36.72 P-value <0.0001 <0.0001 0.1883 C.V. = coefficient of variation (%). Table 6: Crop phenology in calendar dates for all sites, 2014 growing season. Plant Phenology Rossville Scandia Ottawa Planting Date 19-May 22-May 26-May V-5 growth stage 27-Jun 2-Jul 1-Jul Flowering 1-Aug 4-Aug 8-Aug Mid-Reproductive 29-Aug 2-Sep 11-Sep Harvest 26-Sep 14-Nov 30-Sep details about all treatment combinations can be visualized in Table 2. Fertilizer application by nutrient (expressed in lbs per acre) per treatment combination is presented in Table 3. Herbicides and hand weeding were used to maintain no weed interference for the entire season, and soil nutrient concentrations (other than N) were maintained above the recommended critical levels (through inorganic P/K applications). In-season measurements for soil testing were collected during V-5 to V-8 (five to eight leaves) growing stages of the grain sorghum. Soil samples were taken at 0-6 inches and 0-24 inches. Information for Ottawa and Scandia is presented in Table 4. Nutrient levels were quite different for this sampling time at the Scandia location from the pre-season soil test results. Soil samples from Ottawa were taken at this time. No pre-season data are available for Ottawa. The numbers presented show the averages across all treatment combinations. Stand counts were taken by counting the final number of plants emerged in four 17.5-foot sections of row in each plot. Plant population counts were taken approximately at V5 stage (40 days after planting). Final plant population at each site is presented in Table 5. Final plant numbers were achieved successfully with exception of some treatments at diverse locations. Plant uniformity was also a challenge faced with the use of drills for the narrow-row spacing (15”) combinations. The treatments with 30- inch row spacing (treatments #3 and #10) have a greater plant population as compared with the 15-inch row spacing treatment combinations. Except for Scandia, (poor planting conditions), Rossville and Ottawa sites, the plant populations were close to the targeted one of 40,000 plants/A (Table 5). Biomass determination was performed from five consecutive plants per plot at three diverse growth stages: • V5 • Flowering • Physiological maturity Each individual plant was cut at the stem base and separated into different fractions: leaves and stem (vegetative), head, leaves, and stem (reproductive). Each fraction was separately chopped and dried to constant weight at 60o C. Nutrient concentrations are currently evaluated by a commercial lab. Yield information is expressed in bushels per acre adjusted to 12.5 percent moisture content. Yield was collected from the central two rows (30- in. row spacing) or four rows (15-in. row spacing) (5 ft. x 50 ft). Grain harvest index was estimated as the ratio between the grain yield to the whole-plant biomass collected at maturity. Crop Phenology was documented for each site as to properly identified changes in plant growth and nutrient uptake rates (Table 6). The time from planting to flowering was similar at all locations, with approximately 72 to 75