Evaluation of Simultaneous Application of Powder Sulfur and Thiobacillus thioparus to Improve Calcareous Soils of Western Iran

Powder sulfur is the most common used substance for improvement of calcareous soils particularly their pH while its efficiency in the soil is highly depend on its oxidation condition. The Objective of this research is to evaluate the efficiency of various amounts of sulfur to improve calcareous soils in presence of sulfur-oxidizer bacteria. Hence, 15 soil columns containing a calcareous soil including four sulfur treatments labeled S(0.125), S(0.250), S(0.375) and S(0.500) and a control treatment with lack of sulfur, each with three replications were manufactured and inoculated using Thiobacillus thioparus and then brought under leaching once a two weeks for six months. The results showed that the leakage of sulfate caused by sulfur oxidation was intensified for the temperatures above 25°C and reached a maximum in 30°C. Moreover, statistical analysis among sulfur treated columns approved presence of positive significant relationships between temperature and sulfate leakage (α= 0.01) from one hand, and negative significant relationships between temperature and pH (α= 0.01) on the other hand.