Supported by the National Key Research and Development Program (2017YFD0300707) and the National Natural Science Foundation of China（Nos. 41571280 and 41101276）
[Objective] The climate in Northeast China is very cold, so that the paddy fields therein have a long fallow period when the soil is frozen for most of the time. Rice is quite short in life cycle and calls for high soil temperature and seasonal flooding for healthy growth. The practice of rice straw returning is quite popular, but little is known about how the exogenous rice straw is decomposed and how carbon (C) and nitrogen (N) in the decomposing rice straw is released during the fallow season and the rice-growing period as affected by hydrothermal condition in Northeast China.[Method] In this study, an outdoor incubation experiment was carried out using dual-isotope-labeled (13C and 15N) rice root, stem and leaf for tracing of the elements with the stable isotope mass spectrum analysis technique, to characterize dynamics of the decomposition rate of the incorporated rice root, stem and leaf and the release rate of C and N from the decomposing rice root, stem and leaf in the paddy soil. Isotope-labeled rice root, stem and leaf were added to the paddy soil in autumn.[Result] Decomposition rates of the straw in Treatment S1 (labeled root + unlabeled stem and leaf) and Treatment S2 (unlabeled root + labeled stem and leaf) was determined to be 30.2% and 34.5%, C release rate to be 30.9% and 38.2%, and N release rate to be 7.4% and 35.0%, respectively, at the end of the fallow period (November to May). One year after the amendment, decomposition rate of the straw reached 66.5% and 66.6%, C release rate did 63.7% and 65.8%, and N release rate 28.6% and 51.1% in Treatment S1 and S2, respectively. The N release rate of root was significantly lower than that of stem and leaf (P< 0.05).[Conclusion] One year after the amendment of rice root, stem and leaf into the paddy soil, the decomposition rates of rice roots, stem and leaf all reached about 65%. The release of C from the rice root, stem and leaf varied synchronously with the decomposition of the materials in rate. However, the release of N from the rice root, stem and leaf was relatively slow, especially that from the root. Higher temperature obviously promoted decomposition of and C and N release from the straw in the soil. This study is expected to be of great significance for scientific evaluation of the recycling of C and N in the incorporated rice straw in the paddy soil in Northeast China.
刘晖,刘杰,张玉玲,金鑫鑫,安晶,范庆锋,虞娜,邹洪涛.外源水稻根系和茎叶碳氮在稻田土壤中释放的特征[J].土壤学报,2021,58(4):989-997. DOI:10.11766/trxb201909260505 LIU Hui, LIU Jie, ZHANG Yuling, JIN Xinxin, AN Jing, FAN Qingfeng, YU Na, ZOU Hongtao. Release of Exogenous Carbon and Nitrogen in Rice Root, Stem and Leaf in Paddy Soil[J]. Acta Pedologica Sinica,2021,58(4):989-997.复制