Microbial and chemical risks of organic fertilizers based on by-products of livestock farming
M.V. Kuznetsova1,2, D.O. Egorova1, D.A. Kochergina1, T.D. Kiryanova1, I.N. Zhdanova 3, D.S. Fomin3, E.S. Gorovitz2
1Institute of Ecology and Genetics of Microorganisms of Ural Branch of Russian Academy of Sciences – affiliation of Perm Federal Research Centre of Ural Branch of RAS, 13 Goleva Str., Perm, 614081, Russian Federation
2Perm State Medical University named after Academician E.A. Wagner, 26 Petropavlovskaya Str., Perm, 614990, Russian Federation
3Perm Research Institute of Agriculture – branch of the Perm Federal Research Center of the Ural Branch of the Russian Academy of Sciences, 12 Kul’tury Str., Lobanovo village, Perm Krai, Russian Federation
Agro-industrial complexes are a major source of environmental pollution. Organic fertilizers based on by-products of livestock farming may contain pathogenic microorganisms, residual concentrations of antibiotics, vaccines, heavy metals, pesticides and, getting into the soil, cause their microbial and chemical pollution.
The aim of this study was to assess health risks based on analyzing microbial and chemical pollution due to by-products of livestock farming with different storage duration and conditions.
Our research objects were represented by samples of organic livestock wastes that differed per storage duration and conditions (non-composted and composted); they were taken at three large agro-industrial complexes in the Perm region. Strains of Escherichia coli were isolated from the wastes, in which the pathogenicity genes of diarrheagenic E. coli were detected. Concentrations of major pollutants posing health risks were determined in livestock farming by-products, including toxic substances (lead, cadmium, copper, manganese, magnesium, zinc, cobalt, iron), pesticides (gamma isomer of hexachlorocyclohexane – HCH, dichlorodiphenyltrichloroethane – DDT), and polychlorinated biphenyls (PCBs). Health risks were assessed.
Representatives of the Salmonella genus and opportunistic enterobacteria were shown to be able to survive in wastes for one month. In addition, levels of heavy metals in some samples were higher than the maximum allowable concentration (MAC) for soils. The sanitary indicators of fertilizers (by-products with a one-year storage period) did not exceed the safe standards; the samples did not contain diarrheagenic E. coli strains, organochlorine pesticides or polychlorinated biphenyls. The indicators characterizing the risk of prevalence of multiple antibiotic resistance and hazard indices of heavy metals were within permissible limits. By-products of livestock farming with a one-year storage period are safe in microbial and chemical terms and can be further used as a fertilizer.
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