Respiration of Rhizosphere and nonrhizosphere soil in a greenhouse experiment with Oat plants (Avena sativa L.)

Fluxes of ¹³C-labeled carbon assimilated by plants and transposed to the rhizosphere and soil under continuous labeling in the atmosphere enriched with ¹³C-CO₂ were studied in a greenhouse experiment with oat plants (Avena sativa L.). The dynamics of ¹³C-CO₂ emission from soil with plants closely correlated with the dynamics of labeled C in the microbial biomass and the dissolved organic matter in the rhizosphere; characteristic maxima coincided with the periods of intense release of organic substances from the roots to the rhizosphere and soil. The contribution of living roots and rhizosphere microorganisms to the total emission of CO₂ from the soil surface varied from 44 to 52%. The contribution of the decomposition of dead roots comprised 12-27%. The percentage of C assimilated and translocated to the rhizosphere and nonrhizosphere soil comprised 9 to 27% of net primary production.