Biological carbon assimilation and dynamics in a flooded rice – Soil system |
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| Institution: | 1. Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha City, Hunan Province 410125, China;2. Department of Sustainable Soils and Grassland Systems, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK;1. Key Laboratory of Agro-ecological Processes in Subtropical Region, The Chinese Academy of Sciences, Hunan 410125, China;2. Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China;1. Key Laboratory of Agro-ecological Processes in Subtropical Region, The Chinese Academy of Sciences, Hunan 410125, China;2. Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, Changsha 410125, China;3. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing 210008, China;4. Hunan Province Environmental Monitoring Center, Changsha 410019, China;5. University of the Chinese Academy of Sciences, Beijing 100049, China;1. Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China;2. Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang, Guangxi 547100, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;1. Changsha Research Station for Agricultural and Environmental Monitoring & Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China;2. ISA-CAS and UWA Joint Laboratory for Soil Systems Biology, Hunan 410125, China;3. Institute of Agricultural and Biological Resources Utilization, Hunan Academy of Agricultural Sciences, China;1. Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, People’s Republic of China;2. Huanjiang Observation and Research Station for Karst Ecosystem, Chinese Academy of Sciences, Huanjiang 547100, People’s Republic of China;3. Yiwu Environmental Protection Bureau, Yiwu 322000, People’s Republic of China;4. College of Resources and Environmental Sciences, Hunan Normal University, Changsha 410081, Hunan, People’s Republic of China;1. Dongting Lake Station for Wetland Ecosystem Research, Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China;2. College of Life Science, Sichuan University, Chendu 610064, China |
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| Abstract: | Information on the input, distribution and fate of photosynthesized carbon (C) in plant–soil systems is essential for understanding their nutrient and C dynamics. Our objectives were to: 1) quantify the input to, and distribution of, photosynthesized C by rice into selected soil C pools by using a C14 continuous labelling technique and 2) determine the influence of the photosynthesized C input on the decomposition of native soil organic carbon (SOC) under laboratory conditions. The amounts of C14 in soil organic C (SOC14) were soil dependent, and ranged from 114.3 to 348.2 mg C kg?1, accounting for 0.73%–1.99% of total SOC after continuous labelling for 80 days. However, the mean SOC14 concentrations in unplanted soils (31.9–64.6 mg kg?1) were accounted for 21.5% of the rice-planted soils. The amounts of C14 in the dissolved organic C (DOC14) and in the microbial biomass C (MBC14), as percentages of SOC14, were 2.21%–3.54% and 9.72%–17.97%, respectively. The DOC14 and MBC14 were 6.72%–14.64% and 1.70%–7.67% of total DOC and MBC respectively after 80-d of rice growth. At 80-d of labelling, the SOC14 concentration was positively correlated with the MBC14 concentration and rice root biomass. Rice growth promotes more photosynthesized (newly-derived) C into soil C pools compared to unplanted soils, reflecting the release of root exudates from rice roots. Laboratory incubation of photosynthesized (plant-derived) C in soil decreased the decomposition of native SOC (i.e. a negative priming effect), in some, but not all cases. If this negative priming effect of the new C on native SOC also occurs in the field in the longer term, paddy soils will probably sequester more C from the atmosphere if more photosynthesized C enters them. |
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