Abstract
A study was conducted to evaluate sulfate release kinetics in two different texture of calcareous soil (clay and loamy sand) amended with different levels of agricultural sulfur and to select the best mathematical models which describes the mechanism of biological oxidations of sulfur under different time of incubation. Agricultural sulfur was mixed with soils at rates (0, 5, 10, 20) gm.S-1. kg-1 soil. Water was added to raise the soil moisture content to field capacity, the soil samples were incubated at 298° K. Sulfate release was monorated by using anion capsule resin (OH-resin) inserted in soil for 1, 7, 14, 21, 35 day. Five kinetics models (zero order, first order, parabolic diffusion, Elovich and power function). Were applied to describe sulfate and hydrogen release rate coefficient, in order to select the best model the results showed a significant increase in the accumulated sulfate release with sulfur treatments with increasing. The results showed a significant increase in accumulated H and SO4= release with sulfur treatment with increasing incubation period. The result showed also that parabolic diffusion equation was the best one to describe the rate coefficient of H+ and SO4= that range from 21 to 78 in clay soil and 19 – 69 day -12 in loamy soil for hydrogen release while the rate coefficients of SO4= release were ranged from 9 to 36 and 19 to 47 day -12 for clay and loamy soils respectively.
