An organic matter content of soil is one of the major parameter representing soil quality. A pot experiment carried out to determine the effect of humic+fulvic acid (HFA) is considered to be the most effective part of the organic matter on biological activity of different region soils. In this study, HFA doses of 0, 500, 1000, 2000 ppm were applied to soil collected from 7 different regions of Turkey and corn seeds were sown. Following the harvest, the colony forming units of microorganisms, CO2 production, dehydrogenase enzyme activity (DHA) and microbial biomass carbon (MBC) were analysed to evaluate biological activity of soils. The results obtained revealed that the HFA was effective in terms of parameters determined but, the effectiveness was variable in terms of the region studied. The lower values were observed in the soil taken from Konya region according to the biological activity parameters of CO2 production, DHA and MBC. The higher values were determined in soil taken from Antalya or Samsun. According to HFA doses, increment until 1000 ppm resulted in significantly higher values of biological activity parameters whereas, increment from 1000 to 2000 ppm was not effective on the parameters mentioned above, even decline was observed in some cases.