A SENSITIVE SANDY SOIL UNDER PASTURE AS MICROORGANISM HABITAT PROVIDER

Abstract

The sandy soils are sensitive ecosystems, being in a precarious equilibrium with the pedolandscape conditions, any changes could bring drastically modifications into the soil environment. The researches had been performed in Suceava Tableland, in Stephan the Great area, on a Luvosol albic-psamic, lamelar. The researches in the paper focused on the upper part of the argic horizon, on Bt₁ sub-horizon characteristics at macro- and microscopic scale. In this respect, at the macro-morphological level, the Bt₁ sub-horizon is composed of a sequence of thick lamellae (3–5 cm) separated by the inter-lamellar spaces. The granulometric analysis showed that the lamellae had a medium loamy texture, while the inter-lamellar spaces had coarse granulometric composition. At micromorphological level, the image emphasized, in the lamellae, the presence of the clayey±Fe±humiccoating the mineral grains and clogging part of the inter-granular spaces. The results of the microbiological investigation showed a concentration of the microorganisms into the lamellae, while in the inter-lamellar spaces, their development has been scarce. The total counts of bacteria and fungi registered low number (16.81 x 10⁶ viable cells x g^-1d.s. and 1.026 x 10³cfus x g^-1d.s., respectively). Despite of these results, the data of the global indicator of the soil microbiological activity, the soil respiration respectively, attend high level of activity (31.357 mg CO₂ x g^-1d.s.). The researches pointed out that the sandy soil is a very sensitive environment for the soil life, but the presence of the clayey±Fe lamellae proved to be a hospitable habitat.