The aim of the study was to assess the long-term changes of chemical and biological properties of soil treated with various application rates of municipal sewage sludge (SS) under the condition of field and laboratory experiments. The experiment scheme included five treatments: 1 – the control; 2 – 10 t of SS dry matter per hectare; 3 – 20 t of SS dry matter per hectare; 4 – 40 t of SS dry matter per hectare and 5 – 60 t of SS dry matter per hectare. Considerable dose-dependent enhancement of carbon and nitrogen contents as well as enzyme activities were observed, particularly when high rates of sewage sludge were applied. It was proven that such rates allowing for longer durability of favorable changes in the soil and did not pose risks for its quality in the context of heavy metal and PAH concentrations as well as enzymatic activity. The presence of Phalaris arundinacea plants had a positive impact on the chemical properties and biological condition of soil, expressed in the lower content of heavy metals and PAHs and higher activity of soil enzymes. Significant correlations between all analyzed parameters in the field and laboratory experiment indicates that such studies allow a reliable assessment of the impact of SS application on the chemical and biological condition of soils within a given ecosystem.