Our study involved composts
containing municipal sewage sludge and
either straw or leaves. The straw-based compost
was characterized by higher pH and salinity and
greater share of dry weight than leaf-based one
(Table 1). On the other hand, the leaf-based compost
contained more organic carbon, nitrogen,
phosphorus, sulfur and heavy metals, mainly lead
and cadmium. Compost maturity and stability of
organic matter is determined by its C:N ratio, the
recommended range of which is 20-30:1 [Davidson
et al. 1994, Kosobucki et al. 2000, Krzywy 2007].