Effect of mineral and organic additions on soil microbial composition

The aim of the study was to evaluate the effect of different mineral-organic mixtures on changes in soil microbial composition and chemical properties. The design of the pot experiment included 6 treatments: soil without fertilization ??? C, soil fertilized with mineral NPK fertilizers ??? MF, soil with NPK + 3 or 6% lignite and 3% zeolite-vermiculite composite (MF+CW3%, MF+CW6%), soil with NPK + 3 or 6% leonardite and 3% zeolitevermiculite composite (MF+CL3%, MF+CL6%). The test plants were spring oilseed rape and spring wheat. The highest number of microorganisms was observed: for oilseed rape ??? in the soil of the MF+CW3% and MF+CW6% treatments, and for wheat ??? in the soil of the MF+CL3% and MF+CL6% treatments. The maximum percentage increase in the number of analysed microorganisms, for spring rape and spring wheat, respectively, was: bacteria 190% (MF+CW3%) and 1198% (MF+CL3%), mould fungi 221% (MF+CW3%) and 1601% (MF+CL3%), Azotobacter spp. 248% (MF+CW6%) and 251% (MF+CL3%), actinomycetes 116% (MF+CW3%) and 251% (MF+CL3%). The beneficial effect of the applied mineral-organic mixtures on soil biological activity is closely related to the effect of these materials on soil chemical properties, such as pH or electrical conductivity, which was confirmed by the calculated correlation coefficients.