Quantitative Research On Transformation Of Assimilative Carbon To Soil Organic Carbon Pools Under ¹⁴C Continuous Labeling

Crop-assimilated carbon represents a key linked component of the C cycle in the soil-plant-atmosphere continuum. Research in this area is therefore indispensable for understanding of the process and of the distribution and transformation characteristics. On this research, 14C continuous labeling was applied in a closed system to investigate (i) the distribution and transformation rules of crop-assimilated C in paddy soil; (ii) its contribution to SOC and the function of microorganisms in the transformation of assimilated C. The results showed that:(1) The transportation amount of rice assimilative carbon reached 114-318 mg kg-1 after 80 days'incubation, and soil dissolved organic carbon and microbial biomass carbon increased to some various degree; although soil differs from productivity (4.9-15.8 g/plot), their rhizodeposition efficiency is in approximation. (2) Quantitative analysis the contribution of rice assimilation carbon to soil microbial biomass carbon run up to 12%, indicating that photosynthetic products transfer to soil microbial biomass carbon is rapid; (3) We cleared the proportion of rice assimilative carbon to rice carbon accumulation, to soil organic carbon, to soil dissolved organic carbon, and to microbial biomass carbon; (4) Of 14C-SOC and 14C-MBC input into paddy soil, there was a significant positive correlation between them, showing that soil microorganisms affect rhizodeposition efficiency directly. (5) Input rice assimilation carbon promoted decomposition of native organic matter, some 16% amount assimilation carbon was mineralized.