Effect of composting and vermicomposting on properties of particle size fractions

• Distribution and agrochemical properties of size fractions were determined.
• Compost based on kitchen and paper waste was the finest among monitored composts.
• Vermicompost was the finer and more homogeneous compared to classical compost.
• Compost particles less than 5 mm exhibited the best agricultural potential.
• Agrochemical properties of the finest vermicompost exceeded the classical compost.

The objectives of the study were to compare the effects of the composting and the vermicomposting processes on the distribution of particles into three size fractions, and to assess the agrochemical properties of the size fractions of the composts and the vermicomposts. Three different mixtures of biowaste were subjected to two thermophilic pre-composting, and then the mixtures were subsequently subjected to 5 months composting and vermicomposting under laboratory conditions. Vermicomposting was able to achieve the finer and more homogeneous final product compared to composting. For compost, the highest portion of the finest fraction was achieved from products which originated from kitchen waste containing used paper, followed by digestate with straw, and finally sewage sludge with garden biowaste. In most cases, compost particles which were less than 5 mm exhibited the better agricultural potential than coarser compost. However, agrochemical properties of the finest vermicompost exceeded classical compost.