engleski

Heavy metals in animal manure and effects of composting on it

Composted manures play an important role in maintaining soil fertility, but they can be a significant source of heavy metals, so it is necessary to compare their content with permitted values. For this purpose, manure was composted from cattle, horse breeding, pig and poultry production, concentrations of heavy metals monitored during composting, and their usability determined. Manure was composted in small piles with mixing and sampled at the beginning and after 90 and 270 days. Content of micronutrients and heavy metals was analyzed by aqua regia destruction of dry sample. The results indicate significant concentrations of essential heavy metals Fe, Mn, Zn, Cu, Ni and Mo in the compost. Regarding the content of Fe and Mn the highest quality was obtained from pig manure, and the very low concentration of Fe was in chicken compost (852.3 mg•kg-1), and Mn in cattle (375.0 mg•kg-1). The lowest concentration of Zn was in the compost obtained from horse manure (94.3 mg•kg-1), while in the others it ranged from 294.5 up to 697.6 mg•kg-1. The highest concentrations of other heavy metals of this group were found in pig and chicken compost, while they were significantly lower in the others. The concentration of Cu and Mo was significantly increased only during the first three months of composting, while the concentration of Ni continuously increased. Highest concentrations were determined for Cr and the lowest for Cd. Due to the relatively highest concentrations of Cd, pig compost was of the lowest quality, while the highest quality composts were cattle and chicken composts. In terms of concentrations of micro¬nutrients, the best compost for fertilization of soils is pig compost, most benefits as a potting medium has cattle compost and only horse compost can be used in organic production.

manure ; composting ; compost ; heavy metals

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