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Fluid Journal : Winter 2018
9 The Fluid Journal Winter 2018 Fluid Nitrogen-Sulfur Formulations In Cotton Used to mitigate sulfur deficiencies and maximize cotton yields. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Winter 2018 • Vol. 25, No. 4, Issue #99 Dr. Hunter Frame Summary: Overall the 2016 growing season was marked by challenging weather events which limited the productivity of cotton in Virginia and North Carolina. Yields at two of the three locations were low and responses in yields to N/S formulations were limited at these locations. One location, Suffolk, was high yielding and responsive to N/S formulations. All sites were responsive to N/S formulations during the growing season in terms of NDVI and tissue N and S concentrations. Though lint yields were limited by environmental conditions at each location there were common responses across locations which allowed for inference into the role of S in cotton production on low CEC, low organic matter, and low water holding capacity soils commonly found in the coastal plain regions. Lint quality characteristics were tested and significant responses to N and S treatments were sparse during the study. ▼ DOWNLOAD Three trials were implemented across the upper southeast coastal plain cotton production region in 2016. The trial locations were Tidewater Agricultural Research Center in Suffolk, VA., Everett Farms in Southampton County, VA (SHC), and the Peanut Belt Research Station in Lewiston NC (LEW). The study was a randomized complete block design with; four replications of each treatment. Treatments were applied to four row plots measuring 35 ft. in length and 12 ft. wide. Prior to planting, a composite soil sample was taken at 0-6, 6-12, 12-24, and 24-36 inch depths and analyzed for soil ammonium and nitrate concentrations using a 2M potassium chloride (KCl) extraction procedure. All other nutrients, except nitrogen (N) and sulfur (S), were applied based on soil test recommendations and/or extension recommendations for North Carolina and Virginia cotton production. There were a total of seventeen fertilizer treatments (Table 1). The primary fluid N sources were urea ammonium nitrate (UAN) solutions (28- 32% UAN) and granular urea. A bulk blend of granular urea and ammonium sulfate (AMS) was applied at 100 pounds of N per acre with S rates ranging from 0 to 30 pounds S per acre (Treatments 2-5). The granular fertilizers were spread uniformly over the plot area by hand. The total N application rates for the fluid N-S sources were 60, 100, 140 lbs. N per acre (Treatments 5-17). Nitrogen was applied in split applications with 20 pounds N per acre applied at planting and the remaining N applied at the 1st square stage of development. To achieve the varying ratios of N-S solutions, UAN was mixed with ammonium thiosulfate (ATS) (12-0-0-26S). Ammonium thiosulfate was chosen for its high S concentration over AMS solutions (8-0- 0-9S). The four ratios were: no-applied S, 8:1, 4:1, and 2.66:1. The analyses of each fluid N-S side-dress fertilizer material were 32-0-0, 24-0-0-3S, 24- 0-0 -96S, representing fluid fertilizer formulations currently feasible using UAN and ATS solutions (Tom Fairweather, personal communication). The fluid fertilizers were applied using pressurized carbon dioxide system mounted on a four (36 inch) row applicator outfitted with coulters/fertilizer injection knives approximately 6 inches to the side or the row. All N sources were treated with the urease inhibitor N-(n-butyl) thio- phosphoric triamide (NBPT), to minimize Fig. 1 Cotton treated with no N/S (A) and 140 lb N acre-1 with no S applied as 32-0-0 injected at Suffolk in 2016.