Pseudomonas fluoresces occurrence in soil after fertilization with sewage sludge

Abstract

The aim of the study was to analyze the occurrence of Pseudomonas fluorescens in urban soil in the second year after fertilization with unprocessed sewage sludge from the wastewater treatment plant in Sokółka and processed sludge from wastewater treatment plant in Bialystok. The study was conducted on experimental plots located in the green belts along the main roads in Bialystok
(Piastowska and Hetmańska streets). For the studied soil, two different types of sewage sludge were used: after-press dewatered sludge from the treatment plant in Sokółka and dry sludge in the form of pellets from the treatment plant in Bialystok. The experiment plots were fertilized with three doses of sewage sludge: 0-control, 14.5 and 29 Mg D.M./ha. In the second year after application of sewage sludge, microbiological tests of the rhizosphere area showed seasonal fluctuations in the number of
Pseudomonas fluorescens bacteria. The highest number of Pseudomonas fluorescens bacteria was observed in April and in October, while the lowest number of bacteria occurred in July, which could have been conditioned by atmospheric factors. The analysis of the correlation indicates that in the urban soil mixed with sewage sludge the number of Pseudomonas fluorescens was significantly positively correlated with C:N ratio, organic carbonand content of phosphorus.