Abstract: Based on the data of 12 years experiment in the Taoyuan Experimental Station of Agroecosystem Research of Chinese Academy of Sciences,this paper studied the contribution of organic materials cycling to the soil organic carbon turnover in a red soil paddy ecosystem.The results showed under the cycling of organic materials,the accumulation of soil organic carbon was promoted,the fraction of soil humus was improved,and the quality of soil organic matter was reformed.The annual increasing rate of soil organic carbon during 12 years was up to 0.37 g·kg^-1,while the increment of soil easily oxidized organic carbon,humic acid and fulvic acid was 3.8,3.06 and 1.63 g·kg^-1,respectively.The simulation results of SCNC model (Soil Carbon and Nitrogen Cycle) showed that after 50 years of organic materials cycling,soil organic carbon content could be increased by 8.3-18.9 g·kg^-1,and the increasing rate could be up to 62.0%-140.7% in the red soil paddy ecosystem.

Key words: Solar greenhouse, Continuously cropped soil, Phenolic acids, Microflora, Enzyme activity