Abstract: Increasing concentration of atmospheric CO₂ has dramatic effects on plant, which could indirectly effect on soil biota and related processes in soil. Response of soil biota is important for plant and ecosystem. This paper summarized the changes of plant under elevated CO₂ and responses of soil biota and processes in soil including mycorrhiza, nodule, rhizosphere microorganisms, plant pathogen, soil fauna and decomposition. Researches which should be stressed in the future were also pointed out in the paper.

Key words: rice straw returning mode, double cropping rice, yield, carbon form, carbon pool management index.