Abstract: Biogas slurry produced from anaerobically digested pig waste from an intensive pig farm was used for study. Population of fecal coliforms in the slurry under storage (covered or open) in winter and spring, and summer and autumn was monitored. And the slurries, different in coliform population [10⁴  (Treatment WF), 10⁵ (Treatment LF), 10⁶ (Treatment MF) and 10⁷(Treatment HF)] were top-dressed separately on lettuce in the field. Samples of soil and lettuce were collected from the field 3, 10, 17 and 24 days after the top-dressing for analysis of population of coliforms in the soil, on the surface of and in the lettuce. Results show that coliforms in the slurry lived longer in SA, and open storage reduced the population of coliforms. After 50 days of storage, all the treatments failed to meet Grade III criteria of the “Integrated Standard for Discharge of Wastewater GB 8978—2002”, except for the treatment of open storage in WS. The more the coliforms that survived in the slurry, the more the coliforms that could be found in the soil, on the surface of and in the lettuce that was top-dressed with the slurry. However, the population of coliforms varied with time. During the monitoring period, Treatment WF under open storage was significantly lower than the others in population of coliforms in the soil. On the 3^rd day after the top-dressing, Treatment WF was much lower than Treatments HF and MF in number of coliforms on the surface of and in the lettuce, and 24 days after the top-dressing, coliforms were no longer detected in the lettuce in all the treatments, which is up to the “National Standard for Food Safety”, however, they could still be found on the surface of the lettuce with logarithmic value of the population being lower than 3.51, which fails to the “National Standard for Food Safety”. 

Key words: fecal coliform, biogas slurry, storage, top-dressed in the field, dynamic change