Use of Sewage Sludge and Organic Matter Regime of Sod-Podzolic Soil

It is shown that sewage sludge formed during sewage treatment contains a significant amount of organic matter, nitrogen, and ash elements, which can be used by plants. The paper presents the results of a 3‑year microplot experiment on sod-podzolic soil to determine the effect of sewage sludge added together with sawdust, peat, and straw at different ratios (the total rate was 60 t/ha). The parameters of the soil organic matter regime (content, reserves, and group and fractional composition) were studied. The substrates used with sewage sludge led to a significant increase in all parameters compared to the control experiment (without fertilizers). A trend towards a decrease in the fertilizing effect was observed when the ratio between sewage sludge and additional organic components increased from 1 : 1 to 1 : 3. Fresh sludge used together with peat or sawdust at a 1 : 1 ratio proved to be more effective than the compost based on sewage sludge.