Formation of microelemental composition and properties of soils under model phytocenoses in soil lysimeters.

The soil formation on noncalcareous loam under different phytocenoses in soil lysimeters (Soil Experimental Station of Moscow State University) for 49 years has led to a decrease in acidity and an increase in the content of organic matter, microelements, and heavy metals in the surface soil layer. The rate of microbial CO emission and the microbial biomass content reached the maximum values under the mixed forest stand followed by the broad-leaved forest, then spruce forests, perennial grasses, and fallow. The minimum values of these parameters were characteristic of the black fallow. The percentage of C in the organic carbon content of the soils under the broad-leaved forest was 2.7; in the mixed forest, spruce forest, fallow, and black fallow, it was 1.9, 1.2, 0.9, and 3.3, respectively. The maximum accumulation of heavy metals was recorded in the litter and at the depth of 2-15 cm. The Zn content in the soils under the woody vegetation was 18-20 times higher than in the parent mantle loam; in the soils under perennial grasses and in the plots without plants, it was 14-16 and 5 times higher, respectively. The biogenic accumulation and aerial dust transfer of heavy metals are responsible for the differences in their accumulation between the soils of the model phytocenoses and soils without vegetation. The content of elements in the dust exceeded that in the parent loam by 200-300 times for Zn, 20-40 for lead, 6-60 for nickel, and 20-30 times for strontium and barium. The composition and amount of dust determined the trends in these elements of accumulation in the soils. [ABSTRACT FROM AUTHOR]