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Fluid Journal : Fluid Journal 2005-2007
Spring 2006 FLUID JOURNAL Page 2 where micronutrients were applied in solution with TGMAP at planting, there were yield increases, with a mean increase of 15 percent. Overall, there were 38 comparisons, 22 with positive increases using fluids and 16 with no yield differences. Loamy sand APP. Of eight trials conducted on red-brown loamy sand there were no yield differences between APP and granular fertilizers in six, and a mean yield decrease of 10 percent in three of the trials. Phosphoric acid. There was a single experiment comparing a phosphoric acid-based product with an equivalent granular product on this soil with a grain yield decrease of seven percent with the fluid. TGMAP solution was compared in four experiments with granular MAP. In one case, TGMAP produced higher grain yield over three rates of P (10, 20, and 40 lbs/A of P2O5) than MAP (4%, P...0.01) and in the other three cases there were no significant differences in grain yield. Summing up, there were 13 comparisons on this soil, with four yield decreases with fluids (APP and phosphoric acid), one increase with fluids (TGMAP), and nine with no yield differences recorded. There are likely to be highly complex relationships between how mobile (N) and immobile (P) nutrients with different solubility behave when applied together to the soil. Suspensions Initial research with suspensions on the three soil types described above has indicated that suspensions are likely to perform in a similar way to other fluids in general but as with clear liquids, fertilizer performance varies widely according to formulation and the combination of nutrients used. In 2004, rate response experiments were established with suspensions at two sites on grey highly calcareous soils with a further experiment comparing several commercial fertilizers in granular or suspension form. In this experiment, basal nutrients (N, Zn, and Mn) were applied as granular so that all plots received 20 lbs/A of P2O5, 10 lbs/A of N, 2.7 lbs/A of Zn, and 8.2 lbs/A of Mn, respectively. Results are shown in Figure 1. As in the case of most of the suspensions, the only additive besides clay was acid used to increase the breakdown rate of the granules. Micronutrients Where possible, micronutrients (Mn, Zn, and Cu) were applied in solutions with fluid fertilizers and integral with granular fertilizers. Both zinc and manganese sulfate can be readily mixed with phosphoric acid-urea solution (warning: phosphoric acid and UAN should never be mixed under any circumstances because of the possibility of explosion). In 2000, on a calcareous red-brown sandy loam, P was applied at rates ranging from 0 to 29 lbs/A of P2O5 as phosphoric acid or TSP. No other Figure 1. Grain yield of Wyalkatchem wheat with fertilizer applied in granular or suspension forms at Cungena, 2004. nutrients were applied. There was no yield response to either form of P. At an adjacent site, P, N, and Zn were applied in a factorial experiment as fluid or granular. There were significant responses to all three nutrients with fluids but not with granular. It is apparent that applying micronutrients in solution with NP fluids is the most efficient way to apply micronutrients on these soils. Dr. Holloway is principal research scientist, B. Frischke is research engineer, A. Frischke is research scientist, D. Brace is research assistant, SARDI Minnipa, South Australia; Prof. McLaughlin is senior principal scientist, Dr. Lombi is senior research scientist, CSIRO Land and Water, CSIRO, Adelaide, South Australia, Dr. Armstrong is Senior Research Scientist, Department of Primary Industries, Horsham, Victoria.
Fluid Journal 2002-2004
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