THE EFFECT OF BROWN COAL ON THE MICROBIAL ACTIVITY IN SOILS CONTAMINATED BY HEAVY METALS

The source of organic matter in soil may be brown coal, organic-mineral fertilizers obtained from brown coal, and peat. These substances take part in all processes in soils and influence their physical, chemical, and biological properties. The purpose of the research was to investigate the influence of brown coal introduced into soil contaminated by heavy metals, on microbial activities. The results showed that regardless the soil type, the dose and time of brown coal application, the dehydrogenase activities varied between 0.045 and 0.278 mg TF.g d.m(-1).24 h(-1). Soil enrichment in peptone resulted in increased microbial activity, a compared to samples with lower endogenic activity, which suggests a deficiency of easily available nitrogen forms, due to their sorption on brown coal. Brown coal demonstrates a low degree of mineralization, but simultaneously, very strong sorption properties, which can lead to the reduction of the toxicity of heavy metals. On the other hand, brown coal improves the sorption properties of soil complexes to bind micro-and macro elements, thus limiting their bioavailability. Therefore, nutrients should be added to soil in cases where brown coal is used in the reclamation of contaminated land.