ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 105, No. 3 (2018), p. 211–220
DOI  10.13080/z-a.2018.105.027

Evaluation of contamination levels of different types of composts and their suitability for usage in agriculture



The aim of the study was to investigate the composition of different organic substances and the amount of nutrients in composts produced from green waste, food waste, sewage sludge, cattle manure and digestate as well as to assess the contamination with persistent organic pollutants and heavy metals. Composts produced in 2015 and 2016 in different regions of Lithuania and in different weather conditions were used for the research. Chemical analyses of composts were done according to the international standards and requirements for soil improvement substances. Of all the composts tested, green waste compost had the lowest content of organic matter, nitrogen and phosphorus. The results of the experiment suggest that digestate, which was characterised by the highest organic matter content, contained the smallest quantity of fulvic and humic acids that are of key importance to the recovery of soil organic content. It was established that sewage sludge composts were the most contaminated with heavy metals and polychlorbiphenyls; the content of the analysed polychlorbiphenyls totalled 37.8 µg kg-1 in the samples of the year 2015 and 29.4 µg kg-1 in the samples of 2016. The lowest content of heavy metals and polychlorbiphenyls was recorded in cattle manure and food waste composts. No polychlorbiphenyls were found in the samples of 2015. The findings suggest that sewage sludge compost is the least suitable for being used in agriculture, because of its pollution with heavy metals and persistent organic pollutants. Green waste compost only increased the quantity of organic matter, while compost from cattle manure, food waste and digestate not only improved the soil structure, but significantly increased nutrients concentration.

Key words: fulvic acid, humic acid, organic matter, polychlorbiphenyls, polycyclic aromatic hydrocarbons.

Full text: 105_3_str27.pdf