Microbial pollution of soil around slurry storage lagoons at a pig-farm

Abstract

Hygienic evaluation of the microbial pollution of the soil in a pig-farm at distances of 1.0 m and 30.0 m around the slurry storage lagoons, based on the number of cultivable microorganisms (NCM—log CFU/g slurry/soil) and the number of Escherichia coli (NEc—log CFU/g slurry/soil) was performed in the present study. The results from the investigation demonstrated: - NCM and NEc varied widely, with clear differences between the various elements of the “fresh slurry–stored slurry–soil at 1.0 m from the lagoons and soil at 30.0 m from the lagoon” chain; - NCM in stored slurry was higher than that in fresh slurry. Further, it significantly decreased in soil at a distance of 1.0 m and further decreased in soil 30.0 m from the lagoons when compared to the NCM of the previous element in the chain; - NCM in stored pig slurry and in soil around lagoons correlated very well with air temperature and rainfalls, which allowed developing of regression equations for estimation of the microbial activity. Temperature was the factor with the higher impact in regulation of microbial contamination compared to rainfalls. - NEc in soil at 30.0 m from lagoons decreased 32.4 times over fresh slurry, 11.7 times over stored slurry and 3.0 times over soil at 1.0 m from lagoons, i.e. increasing of the distance from lagoons, led to reducing the NEc in the soil. - The slurry obtained from clinically healthy pigs and stored in lagoons was a potential source of soil pollution with saprophytic microorganisms and coliform bacteria, subject to sanitary control.