Experimental determination of the active organic matter content in some soils of natural and agricultural ecosystems

In incubation experiments, the soil supply with carbon of mineralizable (C min ), potentially mineralizable (C pm ), and active (C ac ) organic matter, and of microbial mass (C mb ) in natural and agricultural ecosystems of Moscow region (gray forest soil) and Catalonia (Xerochrept) was assessed based on the measurements of the C-CO 2 emission. In the gray forest soil, the C pm and C ac contents decreased in the following sequence of ecosystems: forest > meadow > unfertilized agrocenosis; in the Xerochrept, forest > pasture > scrub > agrocenoses with organic fertilizer > unfertilized agrocenosis. A method for measurement of the C mb according to the C-CO 2 emission during an 11-to 14-day incubation of previously dried soils is proposed.