Elimination of fecal indicator bacteria in soils at repeated irrigation with livestock waste
О.E. Chezlova, А.A. Volchak
Section: Social ecology
To determine the survival time of fecal indicator bacteria (coliform bacteria, Escherichia coli and enterococci) in soils, a field experiment was conducted on sod-podzolic gley soil on cohesive sand when disposing of wastewater from livestock farms. During the field season, wastewater was introduced three times by the norms of 90, 180 and 270 m3 / ha. By the end of the vegetation period, the content of coliform bacteria in the soil using the norms of 180 and 270 m3 / ha is 2.17x102 and 2.16x102 CFU / g, respectively; the number of enterococci is 3.94x102 CFU / g and 2.17x102 CFU / g, respectively. To describe the dynamics of the number of microorganisms, a first order approximation was used. During the first irrigation with wastewater, the highest withering rate was observed in E. coli: the extinction constant k was in the range from 0.129 to 0.253 day -1, and the time of a 10-fold reduction in numbers from 17.9 to 10.4 days with irrigation rates of 90 and 180 m3 / ha, respectively. For enterococci, the parameter k ranged from 0.092 to 0.149 day -1, and the time of 90% elimination ranged from 25.1 to 15.4 days with irrigation rates of 90 and 270 m3 / ha, respectively. For coliform bacteria with a watering rate of 90 m3 / ha, k = 0.131 day-1, and the time of 90% elimination is 17.6 days. By the third irrigation with wastewater, the rate of elimination of E. coli, enterococci and coliform bacteria decreased - the constant k decreased by an average of 4.45, 3.79 and 2.12 times, respectively. For an adequate description of the dynamics of indicator bacteria in soils, it is necessary to take into account climatic, soil factors, the amount of wastewater, etc.
ISSN 1995-4301
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