EFFECT OF THE ADDITION OF SEWAGE SLUDGE ON THE COMPOSITION OF HUMIC SUBSTANCES, CONTENT OF HEAVY METALS AND THE PRESENCE OF TWCHODERMA spp. IN THE SOIL

摘要

The goal of this study was to compare the influence of various doses of sewage sludge and cattle manure on the changes of properties of humic substances in Cambisols developed from silty clay. After organic fertilisation, we observed an increase in total organic carbon in all objects fertilised with sewage sludge and cattle manure. Sewage sludge fertilisation influenced changes of the fractional composition of humus, particularly of Ca-humic acids, which was dose-dependent. The sewage sludge increased the amount of mobile forms of fulvic acids. The dose of 50 Mg ha~(-1) of sewage sludge was comparable with 30 Mg ha~(-1) of cattle manure. Sewage sludge fertilisation gives rise to increased zinc content (differences statistically significant between objects with 80 Mg ha~(-1) of sewage sludge and controls). We also studied the influence of sewage sludge on the number of Trichoderma spp. The number of soil fungi from this genus increased with higher doses of used sewage sludge.