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Fluid Journal : Fluid Journal 1996-1998
2 Fluid Journal Fall 1996 Readings at the no-till Beresford site in 1994 were: soil moisture 25.9 percent, organic matter 3.2 percent, and pH 5.9. Soil is silt loam. Soil moisture reading on the clay loam soil at the Highmore site in 1994 was 8.6 percent at seeding depth at planting. Organic matter was 3.2 per-cent and soil pH was 6.5. Planting. Both sites were planted in 30-inch rows with normal planting units using double disk openers. Liquid fer-tilizer was metered with electric pumps and dropped immediately behind the seed tube opening between the double disk openers. Plots. The experimental design for all sites consisted of randomized split plots. All plots were replicated four times. Fertilizer. Type of fertilizer used, rate of P205 per acre, and the rate of total material used are listed in Table 2. Rates used at both locations were 0, 12.5, 25, and 50 lbs/A of P2O5. Because the materials had different grades, the rate per acre of total material used for each phosphorus rate was different (Table 2). Rates of material ranged from 37 lbs/A for 10-34-0 to a high of 278 lbs/A for 9-18-9. Composition of the 9- 18-9 was orthophosphoric acid and potassium hydroxide. Nitrogen and potassium rates also varied with materi-al at any given phosphorus rate (Table 1). The N + K2O rates ranged from 4 lbs/A for 10-34-0 to 50 lbs/A for 9-18-9. Use caution From our observations of seed- placed phosphorus on corn, the safest liquid material was 10-34-0, followed by 7-21-7 and 9-18-9. Liquid 10-34-0 had the least effect on corn stand. In addition to stand reduction, seed- placed fluids also slowed crop emergence. From these studies we make the fol-lowing precautions to minimize risk of stand reductions when placing fertilizer with corn seed in 30-inch rows: 1. Do not use UAN or urea 2. Do not apply more than 10 lbs/ AofN+K2O 3. Do not apply more than 100 lbs/A of 10-34-0 or 70 lbs/A of 7-21-7 4. Reduce rates 50 percent for dry or sandy soils. Gerwing is extension soils specialist, Dr. Gelderiman is manager of soil testing programs, and Bly is soil fertility research associate at South Dakota State University. 0 30 40 50 60 70 80 90 100 110 % Stand 10-34-0 7-21-7 9-18-9 12.5 25 50 0 12.5 25 50 Highmore Beresford Lbs/A-PO 25 Figure 1. Influence of seed-placed liquid fertilizer on corn stand, Gerwing, et al., South Dakota State University, 1994.
Fluid Journal 1993-1995
Fluid Journal 1999-2001