Composting is one of the most used biowaste recycling method. The paper highlights the influence of some natural organic
additives such as cattle and poultry manure on the quality of compost and especially on the content in microelements and heavy
metals. The mature compost showed the following macro and microelements concentrations: total N 1.12-1.38%, P 0.56-0.90%,
K 0.68-0.92%, Ca 1.18-1.70%. Mg 0.38-0.66%. The compost that included cattle manure showed the highest content in humic
substances, i.e. about 24.6%.
The sequential analysis of metals revealed that the mobilisable sulphides had the largest share of the total content in metals, i.e.
Pb 51.05% in the compost with cattle manure; Cd 55.78% in the compost with poultry manure, and As 48.92% in the vegetable
compost without additives.
The very low percentage of available metals for plant uptake proves the efficiency of the organic additives.