C-TRANSFORMATION AND N-TRANSFORMATION DYNAMICS IN THE SOIL

The C- and N-transformation processes were measured over a 11 day-incu bation period under laboratory conditions in a calcareous sandy and a chernozem soil. The experiment was carried out with and without glucos e carbon source under different N nutritional conditions. The water co ntent of the samples was set to a moisture value corresponding to 70% of the maximum water holding capacity. The CO2 production and the ammo nium- and nitrate-N content of the soil samples were determined period ically during the incuabion period. Between the samplings on day 0 and day 2, the ammonium-N quickly nitrificated. In the presence of glucos e, mineral nitrogen was immobilized simultaneously. Between the sampli ngs on day 3 and day 11, the N immobilization and mineralization proce sses were approximately equal. CO2 production in soil samples incubate d with glucose and different quantities of N-supply reached a high val ue already in the first two days of incubation, except the soil sample incubated with glucose and without N-fertilizer. Later, the intensity of glucose decomposition was controlled by the rate of mineralization of the organic N-compounds of the soil.