Functional diversity of soil microorganisms in the conditions of an ecological farming system

In the current study, we investigate the relationships among the soil functional diversity, physicochemical properties and heavy metals presence in an ecological farming system. The soil samples were collected from permanent research sites, from A soil horizons, at a depth from 0.05 m to 0.15 m, in June 2018. In fresh soil samples, we evaluated the metabolic profiles of their microbial communities, using Biolog® Eco Plates. The research showed that the soil physical properties got adjusted after a long-term application of an ecological farming system and that the measured values were stabilised, reaching the levels comparable with the average values for the relevant soil type. It is necessary to devote a continual attention to soil reaction, because soil is naturally acidified through acid atmospheric fallout as well as through calcium uptake-off by plants. The values of the selected heavy metals in the monitored period did not exceed the limit values specified in the Act No. 220/2004 Coll. Based on the results of Shannon’s diversity, we can conclude that the diversity in the investigated sites was low, from moderate to medium. The differences (3.26–3.36) among all 11 study localities were very small and not significant. There were determined the correlations between the soil functional diversity, soil physicochemical properties, and heavy metal contents. The average well colour development (AWCD) positively correlated with soil reaction and with Mg content and significantly negatively correlated with contents of Hg, Zn and Cu; equitability significantly positively correlated with soil reaction, Mg, AWCD and Shannon’s diversity. Spearman’s correlation coefficients confirmed the positive correlation between Shannon’s diversity and soil reaction, AWCD and Mg. In our study, no correlation was found between the functional diversity of microorganisms and the soil physical properties.