Abstract
A study was conducted to evaluate sulfate release kinetics in calcarious soil amended with different levels of agricultural sulfare and to select the best mathematical models that describes the mechanism of sulfate under different time of incubations. Agricultural sulfur was mixed with soil at the rates (0, 250, 500, 750 and 1000 mgS.Kg-1 soil. Water was added to rais the soil moisture content to field capacity. The soil samples were incubated at 298 k˚. Sulfate content of treated soil were determined after (1, 7, 14, 28, 56, 168) day. Five kinetics models (zero order, first order, parapolic diffusion, Elovich, and power function) were applied to describe sulfate release rate coefficient, in order to select the best model according to high (r ) value and lowest (SE) value and to calculate ΔG˚ and t1/2 for sulfate release. The results showed a significant increase in the accumulated sulfate release with sulfur treatments with increasing incubation period but the increase declined in the last periods of incubation. The results showed that power function equation was the best equation to describe the rate coefficient of sulfate accumulation that range from 0-70 to 0-71 mg-kg-day-1 and free energy of reaction was negative and spontaneous change.
