The assimilation and translocation of ¹³C after the 5 h pulse-chase labeling in the ¹³CO₂ enriched atmosphere were studied in the greenhouse experiments with plants of oats (Avena sativa L.) and maize (Zea mays L.). The dynamics of ¹³C in the rhizosphere microbial C (C_mic) and Dissolved Organic Carbon (DOC) were opposite to that for ¹³CO₂ fluxes immediately after the pulse- labelling (in the first 50 h): the minima in C_mic and DOC coincided with the maxima in CO₂ emissions, and vice versa. ¹³C values in the carbon pools oscillated periodically depending on day/night changes. Thus, close inter-relations between ¹³C dynamics in CO₂ emissions, microbial biomass, and DOC were revealed in diurnal scale both for oats and maize plants. Along with pulse-chase labelling, a greenhouse experiment was conducted by growing oats in a continuously ¹³CO₂ labeled atmosphere. The allocation of ¹³C labeled photosynthates in plants, microbial biomass in rhizosphere and root-free soil, pools of soil organic C, and CO₂ emissions were examined. To isolate rhizosphere from root-free soil, plant seedlings were placed into bags made of nylon monofilament screen tissue (16 µm meshes) filled with soil. Two peaks in the dynamics of ¹³C in rhizosphere pools of microbial biomass, DOC, and in CO₂ emissions at the earing and ripeness stages were found during the experiment with continuous labelling in the periods of rapid root growth and starting the root decomposition. Development of rhizosphere effect was monitored using ratio between soil characteristics in rhizosphere and in bulk soil which was called rhizosphere factor (R_f). Minimal mean value of Rf was found for water- extractable N (0.9) while the maximal – for ¹³Ñ pool in DOC (4.3). We divided a number of soil characteristics into three groups – group I with average R_f values equal to 2 and higher, group II with R_f ranged from 1 to 2, and group III with R_f values < 1. The group I included the most labile C pools: labelled ¹³C of photoassimilates in the pools of C_mic and DOC, active Cmic determined by substrate-induced growth response (SIGR) method, water-soluble sugars. The group II consisted of less sensitive soil indices - total microbial C and N, specific growth rate of microorganisms, and total DOC. The only constituent of the group III was water-extractable N. In the course of the experiment with continuous ¹³C labelling, maxima in rhizosphere factors were first revealed for the indices of the group I (period of rapid root growth), then for the group II (period of intensive root turnover and decomposition of dead roots after harvesting). The pool of water-extractable N (group III) had no prominent maxima in the course of the experiment. Thus, both short-term (day/night oscillations) and long-term (in the course of whole vegetation period) dynamics of microbial pools in rhizosphere were connected to the root activity. Dynamics of rhizosphere factor for different soil characteristics demonstrated the development of rhizosphere effect first for the labile C pools, and then – for more conservative C and N pools and specific growth rate of microorganisms. Acknowledgements: this research was supported by the Alexander von Humboldt Foundation, the Russian Foundation for Basic researches, the Russian Ministry of Science and Education, and the Russian Academy of Sciences.