Negar Khoshnevis Gargar - Research Institute of Petroleum Technology
Roozbeh Khosrokhavar - Research Institute of Petroleum Technology
Bahman Khoshnevis - Senior Researcher of Agricultural Engineering

For the study of biological sludge effects on soil microbial community, an experiment was carried out on pots by applying biological sludge (BS) at rates of 0 to 70 ton dry weight.ha-1 (T0-T7 respectively) to the pots having 5 kg soil with 4 replications. The results showed that detrimental effect of BS on plant growth and reduction of their productivity at high levels may be due to presence of pathogenic organisms rather than the toxic levels of heavy metals in BS. Microbial community of soil tolerates BS better than higher plants and total microbial number, their respiration rates significantly increased with increasing BS level in soil.

Biological sludge, soil, environment, respiration rate, microbial community