双季稻地上部、地下部生物量碳变异规律及原位分解过程研究

稻田土壤固碳是“大气-水稻-土壤”相互作用的过程，对稻田地力的提升和可持续利用具有重要意义。水稻地上和地下部生物量碳是稻田土壤固碳的前提。但水稻地上部、地下部生物量碳各自对环境与管理因子的响应机制尚不明确，且水稻地上部、地下部残体的原位分解过程鲜有报道。本项目以南方双季稻地上部、地下部生物量碳在不同环境与管理措施下的变异，及其残体在土壤中的分解过程为核心；首先，通过区域调研，明确水稻地上部、地下部生物量碳与环境、管理因子的耦合关系；然后，结合功能平衡理论，采用土培试验，解析不同影响因子对水稻地上部、地下部生物量碳的作用规律，探索通过环境与管理因子提升水稻地上和地下部生物量碳的可能措施；最后，采用原位试验，结合同位素示踪技术，明确水稻地上部、地下部残体各自在土壤中的分解过程，揭示水稻残体的原位分解规律。研究结果可为提升稻田土壤碳输入量和固碳能力提供理论依据和技术支持。

Soil carbon sequestration in rice field is a result of the atmosphere-rice-soil interaction, which is important to the soil fertility and sustainability of the field. The above- and below-ground biomass carbon of rice are the prerequisites of soil carbon input in the rice field, however their variations under different environmental and management factors remain unclear. Moreover, the in situ decomposition processes of their residues are rarely reported. This project aims to explore the biomass carbon variations and the in situ residue decomposition processes of respectively the above- and below-ground rice within double rice system in subtropical China. First, the impacts of environmental and management factors on separately the above- and below-ground rice are investigated at the field scale to explore their key impact factors; Second, the environmental and management factors are analyzed with pot experiments in terms of functional balance theory, for an improved growing condition of rice with enlarged above- and below-ground biomass carbon; Third, the in situ decomposition processes of the above- and below-ground residues of rice are detected through reciprocal litter transfer experiment to improve the understanding of their fates in soil. This project provides theoretical and technical supports to improve the soil carbon input and soil carbon sequestration of rice field.