The Effect of Inoculation by Thiobacillus Thiooxidans on Phosphorus Availablity in Soil

The aim of this laboratory experiment which includes isolating of sulfur oxidizing bacteria (genus Thiobacillus) from Rhizosphere of some plants and soil treated with sulfur and contaminated with oil and choose the best isolates in reducing the degree of pH and production of sulfate .The isolate T2 is excellent on the rest of the isolates in reducing the degree of pH (8) to (5.51 , 6.07) and produced sulfate 29.1and 114.90 mg.L -1in sulfur and thiosulfate Liquid media as compared with other isolate and used as inoculum in pots experiment .The pots are filled with 4 Kg soil of Qurna Fertilizaed with nitrogen fertilizer and potassium fertilizer as recommended maize and added the sulfur levels (0,2,4,6) tan S. Ha-1 soil and rock phosphate levels (0,400,800,1600) Kg rock.Ha-1 .The pots have been divided into two parts: one of them is inoculation with 15 ml of T2 isolate and the other is left without inoculated and incubated pots laboratory for a month and moisteur tap water to complete the process of sulfer oxidation. After the end of the incubation the pots trancfered to the wired of the college of Agriculture, University of Al-Basra and planted with seeds of maize by (6) seed .pot-1 and placed according to the design (RCBD) with three replications . After germination with 60 days took samples from the soil 14 ,42and exet the experiment and measurement of avilable phosphorus. The results showed that the treatment of best isolated T2, 6 tan.ha-1 1600 Kg rock.ha-1 as gived the highest concentration of available phosphorus in the soil 90.60 ,48.43 and 44.75 mg P. kg-1. soil during the two- six-week periods and after harvest as compared to the treatment without inoculation and non treatment with sulfur and rock phosphate, which has given the available P 15.68 , 12.89 and 8.88 mg P. kg-1 soil during the same periods respectivelly..