Effects of liming on the microbial biomass and its activities in soils long-term contaminated by toxic elements

Abstract

The effects of liming by CaO and CaCO3 on soil microbial characteristics were studied during laboratory incubation of long-term contaminated arable and grassland soils from the vicinity of lead smelter near Příbram (Czech Republic). The CaO treatment showed significant negative effects on soil microbial biomass C and its respiratory activity in both studied soils, despite the fact that microbial biomass C in the grassland soil increased sharply during the first day of incubation. The metabolic quotient (qCO2) in soils amended by CaO showed greater values than the control from the second day of incubation, indicating a possible stress of soil microbial pool. The vulnerability of organic matter to CaO could be indicated by the availability of K2SO4-extractable carbon that increased sharply, particularly at the beginning of the experiment. The amendment of soils by CaCO3 moderately increased the soil microbial biomass. The respiratory activity and qCO2 increased sharply during the first day of incubation, however it is not possible to ascribe them only to microbial activities, but also to CaCO3 decomposition in hydrogen carbonates, water and CO2. The pH values increased more sharply under CaO treatment in comparison to CaCO3 treatment. The improvement of soil pH by CaCO3 could be therefore more convenient for soil microbial communities.

Keywords

• liming
• soil microbial biomass
• respiratory activity
• metabolic quotient qco2
• heavy metals