Changes in the parts of the rhizosphere phosphorus cycle influencing by heavy metal contamination

Abstract

Soil pollution by heavy metals caused many differences of phosphorus transformation. Sediments originated from mining resulted in a significant decrease of total and characteristically LE soluble phosphorus content of topsoil. Each measured parameters indicated soil pollution, but the changes were different: LE soluble phosphorus content and microbial biomass was decreased. As the concentration of heavy metals increase the phosphatase activity is also increase as a response to the depleted phosphate availability. In extreme high concentration, however the metals directly can inhibit these enzymes causing decrease in activity. Higher water extractable organic carbon content of the polluted soil indicated lower transformation (humification) of soil organic matter by lower microbial biomass. Rhizosphere acid phosphatase activity differed by plant species, indicating different phosphorus demand of tested plant species. The highest phosphatase activity was measured in the rhizosphere of rape, and the lowest in the rhizosphere of willow.