Abstract

The effect of 19-years storage period at air-dried condition (4°C) and impact of soils rewetting on microbial presence were studied. The topsoil (0 to 20 cm) of Mollic Gleysol,Eutric Cambisol, Rendzina Leptosol, Orthic Podzol and Eutric Fluvisol were used in the experiment. It was found that 10-days of soil incubation at full water capacity conditions and room temperature is enough for soil microbial regeneration. The moisture content was determined for a range of water potential (pF) values: 0; 1.5; 2.2; 2.7 and 3.2, corresponding to available water and representing different water availabilities for microorganisms and plant roots. According to the results, soil moisture content significantly increased (P<0.001) the abundance of the total number of bacteria and most probable number (MPN) of ammonia oxidizing bacteria (AOB). Molecular analysis (16S rRNA) shows the dominance of Betaproteobacteria genera with the main representatives of Nitrosomonas, Nitrosospira, Delftia, Comamonas and Pseudomonas, as well as exponent species of Firmicutes genera: Clostridium and Ruminococcus.

Key words: 16S rRNA gene analysis, soil water potential, microorganisms abundance, soil rewetting.