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Fluid Journal : Spring 2016
17 The Fluid Journal Spring 2016 aggregation and porosity, leaving a thin layer of impermeable crust at the soil surface. Irrigation water having an ECW less than 0.3 dS/m is a candidate for developing infiltration problems. Physically “picking” or “scratching” this crust will improve infiltration for only a brief period of time until the crust reforms. A long-term remedy is to introduce calcium ions back into the irrigation water, which will, in turn, improve water infiltration rates. Table 1 presents average infiltration rates between June 11 and August 6, 1986 from a trial conducted by the University of California (Lindcove Research and Extension Center in Tulare County). The calcium nitrate, polyacrylamide, and non-ionic surfactant treatments were metered into the irrigation water, whereas the gypsum treatments were applied directly to the soil surface. Reference to “disturbed” in the table means the soil surface was physically disturbed prior to initiating the trial. As presented in Table 1, the most effective treatments were those that provided soluble calcium. Use of fluid Fig. 1: Sodium leached following gypsum or calcium thiosulfate application. Table 2: Common Fluid Calcium Fertilizer sources Source Analysis lb./gal Gal/ton lb. Ca/gal Calcium Ammonium Nitrate (CAN-17) 17-0 -0 -8.8 Ca 12.64 158.2 1.11 Calcium nitrate (CN-9) 9-0-0 -11 Ca 12.2 163.9 1.34 Calcium thiosulfate 0-0-0 -10S-6 Ca 10.4 192.3 0.63 Table 3. Properties of urea sulfuric acid (USA) formulations Analysis 10-0-0-18S 15-0-0-16S 28-0-0-9S Agrium N-pHuric® 10/55 N-pHuric 15/49 N-pHuric 28/27 Verdegaal US-10 US-15 US-28 % H2SO4 55 49 27 Lbs./gallon 12.8 12.65 11.8 Gallons/ton 156 158 169 Lbs. N/gallon 1.28 1.89 3.31 Lbs. S/gallon 2.31 2.03 1.06 pH < 1.0 < 1.0 < 1.0 DOT Placarding Yes No No calcium fertilizers simplifies this practice by eliminating the need for specialized application equipment such as gypsum solutionizing machinery or separate trips over the field to spread dry gypsum. Another useful application of fluid calcium fertilizers is as an aid in combating soil and water sources that are high in sodium. A holistic approach to sodium management would include a bulk gypsum application in the fall ▼ DOWNLOAD