Microbiological and chemical characterisation of composts at different levels of maturity, with evaluation of phytotoxicity and enzymatic activities

Composts from different vegetable residues as well as pig and horse manure at different levels of maturity were used in the present study. In order to characterise the different composts, microbial populations (namely, total aerobic bacteria, actinomycetes, filamentous eumycetes, aerobic cellulolytic fungi and bacteria), physicochemical and chemical parameters (moisture, organic matter, total nitrogen, ammonium nitrogen, C:N ratio, pH, electrical conductivity), self-heating capacity and phytotoxicity (measured by means of the germination test with Lepidium sativion), as well as enzymatic activities [cellulase, lipase (C10), proteasel, were evaluated. The research was designed to focus on a possible correlation between the enzymatic activities and the maturity level of composts. The results showed evidence that the protease:cellulase activity ratio was significantly correlated to the compost phytotoxicity.