Legacy effect of elevated CO 2 and N fertilization on mineralization and retention of rice ( Oryza sativa L.) rhizodepos
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https://doi.org/10.1007/s42832-020-0066-y
RESEARCH ARTICLE
Legacy effect of elevated CO2 and N fertilization on mineralization and retention of rice (Oryza sativa L.) rhizodeposit-C in paddy soil aggregates Yuhong Li1, Hongzhao Yuan1 ,*, Anlei Chen1, Mouliang Xiao1, Yangwu Deng2, Rongzhong Ye3, Zhenke Zhu1, Kazuyuki Inubushi4, Jinshui Wu1,5, Tida Ge1 1 Key Laboratory of Agro-ecological Processes in Subtropical Region & Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China 2 School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China 3 Department of Plant & Environmental Sciences, Pee Dee Research & Education Center, Clemson University, Florence, SC 29506, USA 4 Graduate School of Horticulture, Chiba University, Matsudo, 271-8510, Japan 5 University of Chinese Academy of Sciences, Beijing 100049, China HIGHLIGHTS
GRAPHICAL
ABSTRACT
• Elevated CO2 increased the amounts of rhizodeposits. • The turnover of rhizodeposits derived from N soil was faster than no N soil. • Rhizodeposits derived from elevated CO2 decomposed slower than from ambient air. • Microaggregates and silt-clay were the most and least affected fractions separately.
ARTICLE INFO Article history:
ABSTRACT
Received December 6, 2019 Revised September 12, 2020 Accepted September 21, 2020 Keywords: Rice rhizodeposits Isotope labeling Aggregates Elevated carbon dioxide Nitrogen fertilizer
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 appli
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