Rhizodeposits in rice paddy soil are important in global C sequestration and cycling.This study explored the effects of elevated CO2 and N fertilization during the rice growing season on the subsequent mineralization and retention of rhizodeposit-C in soil aggregates after harvest.Rice(Oryza sativa L.) was labeled with 13CO2 under ambient (400 ppm) and elevated (800 ppm) CO2 concentrations with and without N fertilization.After harvest,soil with labeled rhizodeposits was collected,separated into three aggregate size fractions,and flood-incubated for 100 d.The initial rhizodeposit-13C content of N-fertilized microaggregates was less than 65％ of that of non-fertilized microaggregates.During the incubation of microaggregates separated from N-fertilized soils,3％-9％ and 9％-16％ more proportion of rhizodeposit-13C was mineralized to 13CO2,and incorporated into the microbial biomass,respectively,while less was allocated to soil organic carbon than in the non-fertilized soils.Elevated CO2 increased the rhizodeposit-13C content of all aggregate fractions by 10％-80％,while it reduced cumulative 13CO2 emission and the bioavailable C pool size of rhizodeposit-C,especially in N-fertilized soil,except for the silt-clay fraction.It also resulted in up to 23％ less rhizodeposit-C incorporated into the microbial biomass of the three soil aggregates,and up to 23％ more incorporated into soil organic carbon.These results were relatively weak in the silt-clay fraction.Elevated CO2 and N fertilizer applied in rice growing season had a legacy effect on subsequent mineralization and retention of rhizodeposits in paddy soils after harvest,the extent of which varied among the soil aggregates.

Yuhong Li;Hongzhao Yuan;Anlei Chen;Mouliang Xiao;Yangwu Deng;Rongzhong Ye;Zhenke Zhu;Kazuyuki Inubushi;Jinshui Wu;Tida Ge

Key Laboratory of Agra-ecological Processes in Subtropical Region & Changsha Research Station for Agricultural and Environmental Monitoring,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha 410125,China;School of Resources and Environmental Engineering,Jiangxi University of Science and Technology,Ganzhou 341000,China;Department of Plant & Environmental Sciences,Pee Dee Research & Education Center,Clemson University,Florence,SC 29506,USA;Graduate School of Horticulture,Chiba University,Matsudo,271-8510,Japan;University of Chinese Academy of Sciences,Beijing 100049,China

土壤生态学快报（英文）

[1]Yuhong Li;Hongzhao Yuan;Anlei Chen;Mouliang Xiao;Yangwu Deng;Rongzhong Ye;Zhenke Zhu;Kazuyuki Inubushi;Jinshui Wu;Tida Ge-.Legacy effect of elevated CO2 and N fertilization on mineralization and retention of rice (Oryza sativa L.)rhizodeposit-C in paddy soil aggregates)[J].土壤生态学快报（英文）,2022(01):78-91

rhizodeposit,Rhizodeposits,rhizodeposits

Legacy,elevated,fertilization,mineralization,retention,rice,Oryza,sativa,paddy,are,important,global,sequestration,cycling,This,study,explored,effects,during,growing,season,subsequent,after,harvest,Rice,was,labeled,13CO2,under,ambient,ppm,concentrations,without,After,collected,separated,into,three,size,fractions,flood,incubated,initial,content,fertilized,microaggregates,less,than,that,During,incubation,from,soils,more,proportion,mineralized,incorporated,microbial,biomass,respectively,while,allocated,organic,carbon,Elevated,increased,by,reduced,cumulative,emission,bioavailable,pool,especially,except,silt,clay,It,also,resulted,up,These,results,were,relatively,weak,fertilizer,applied,had,legacy,extent,which,varied,among

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