Investigation of Cadmium Chloride and Cobalt Chloride Concentrations on Some Soil Microbial Indices under Cultivated Savory Plant

In the twentieth century, soil quality and health declining has become a major challenge due to application of poor and polluted water sources. Accordingly, the effect of different concentrations of cobalt chloride and cadmium chloride in irrigation water (0 (control), 100, 200 and 400 mM) on some soil microbial indices during vegetative growth of the medicinal Savory plant (Satureja hortensis L.), in two separate experiments was carried out in a completely randomized design with three replications in the research greenhouse of Agricultural Faculty in Ilam. The experiments were done in 5 kg-pots with 26 cm in height and 30 cm in diameter and longed for two months in 2014. The results showed the highest values of basal respiration rate and substrateinduced respiration in the control and the lowest values of these two indices in 400 mM concentrations of cadmium chloride and cobalt chloride. In terms of soil microbial biomass carbon, the highest value (308 mg.kg-1 soil) and the lowest value (190 mg.kg-1 soil) were found in the control and 400 mM concentration of cadmium chloride salt solution, respectively. The highest (27 mg.kg-1 soil) and the lowest (14 mg.kg-1 soil) values of soil microbial biomass nitrogen were found in control and 400 mM concentration of cadmium chloride, respectively. As well as, the lowest (19 mg.kg-1 soil) amount of soil microbial biomass nitrogen was obtained in 400 mM concentration of cobalt chloride salt solution. The highest amount of microbial quotient, metabolic coefficient and microbial biomass were observed in the control treatment. The microbial biomass carbon and microbial biomass nitrogen ratio increased by irrigation water with different concentrations of cobalt chloride. Increasing the concentrations of cadmium chloride and cobalt chloride showed a negative effect on the microbial quality of the soil, which will pay more attention to the quality of irrigation water for health and quality of the soil microbial community, and hence the quality and overall health of the plant, and ultimately represent health and food safety.