Microbial communities structure, activity and influence on soil organic matter in ArgicPhaeozem

Irrigation, when applied correctly, confers insurance against seasonal variability and drought. Non-adequate management of irrigation water can cause soil erosion, leaching of nutrients, pesticides, pathogens and weeds spreading. Research have been carried out in order to assess changes in the structure, taxonomic composition and activity of microbial communities in irrigated ArgicPhaeozem from Daia, as compared with non-irrigated. The paper presents the results concerning the taxonomical composition of bacterial and fungal microflora in the horizons of the two soil profiles, as well as the level of CO2 released by microorganisms and comparative chromatographic aspects. Increased soil moisture and lowered temperature in irrigated profile, increased bacterial counts and their metabolic activity in Ap horizon comparatively with non-irrigated soil. Bacterial microflora was less abundant in the next two horizons under irrigation, but its effectives increased towards the bottom. Bacterial diversity increased under irrigation but fungal diversity decreased. Soil respiration was, generally more intense in the horizons of irrigated soil profile when compared with non-irrigated one. Changes in quantity and quality of fulvic acids, as well as in the aspect of migration pattern were revealed on circular and ascendant chromatograms due to irrigation.