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Biochar improves soil physical, chemical and biological properties. However, there is a very limited number of studies comparing the effect of various doses of biochar and wheat straw with nutrients on microbiocenotic composition of soil and their connection with selected biochemical and chemical parameters of soil. The aim of this study was to determine the effect of the addition to the soil of wheat straw (WS) and wheat straw biochar (WSB) (300 °C) at 0.2%, 0.5%, 1%, and 2% doses and the addition of nutrients (MF) on microbial community composition (bacteria, fungi, actinobacteria, Azotobacter spp., ammonifiers, nitrifiers, denitrifiers, C. pasteurianum), dehydrogenase activity index, carbon and nitrogen fractions contents and the content of water soluble Cu, Cd, Zn, and Pb. It was demonstrated that coapplication of WS and WSB with MF at 1% and 2% doses increased carbon and nitrogen contents in soil and, in particular, their water soluble fractions (DOC and DON). The synergistic effect of biochar and MF contributed to the increase in the population of soil microorganisms. Dehydrogenase activity index in treatments with the addition of WS, WSB and MF was 1.6–4 times higher compared to the control. The content of heavy metals significantly (p ≤ 0.05) affected dehydrogenase activity and the number of nitrifiers and ammonifiers. It was demonstrated that the content of C and N measured for soil microbial biomass in treatments amended with biochar and MF was much greater than in control treatment and MF. However, our studies suggest that the microorganisms’ response to the addition of biochar with nutrients increased the number and intensified the activity of soil microorganisms.
Mierzwa–Hersztek et al. (Thu,) studied this question.