Effects of Extraneous Tetracycline on Soil-microbial Activity and Microbial Population of Vegatable Field

This study focused on the effects of tetracycline with different contents (0.3,0.6,0.9 mg/kg) on the soil-microbial activities as well as the microbial population by addition of exogenous tetracycline under the rape field planting. The results showed that the activities of microbial biomass under the treatments of different contents of tetracycline were restrained,it reached the lowest level at the 27th day,and it was the CK 6.25%～11.97%; However,different contents of tetracycline activated the soil metabolic quotient obviously. It reached the highest level at the 7th day,and it was the CK 550%～622%. The restrain or activation extents and the conserving time of microbial activities had a significant negative correlation with the tetracycline contents. The activities of soil metabolic quotients in soils treated with tetracycline and those of CK tended to be similar 50 days after treatment.The tetracycline at each concentration tested had significant inhibitory effect on soil microbial population.