Pedosphere 31(1): 191--203, 2021
ISSN 1002-0160/CN 32-1315/P
©2021 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Interactive effects of elevated CO2 and nitrogen fertilization levels on photosynthesized carbon allocation in a temperate spring wheat and soil system
Yu ZHAO1,2, Chao LIANG1, Shuai SHAO1,2, Jie LI1, Hongtu XIE1, Wei ZHANG1, Fusheng CHEN3, Hongbo HE1, Xudong ZHANG1
1Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016(China)
2University of Chinese Academy of Sciences, Beijing 100049(China)
3Jiangxi Provincial Key Laboratory of Silviculture, Jiangxi Agricultural University, Nanchang 330045(China)
      Increasing atmospheric CO2 concentration impacts the terrestrial carbon (C) cycle by affecting plant photosynthesis, the flow of photosynthetically fixed C belowground, and soil C pool turnover. For managed agroecosystems, how and to what extent the interactions between elevated CO2 and N fertilization levels influence the accumulation of photosynthesized C in crops and the incorporation of photosynthesized C into arable soil are in urgent need of exploration. We conducted an experiment simulating elevated CO2 with spring wheat (Triticum aestivum L.) planted in growth chambers. 13C-enriched CO2 with an identical 13C abundance was continuously supplied at ambient and elevated CO2 concentrations (350 and 600 μmol mol-1, respectively) until wheat harvest. Three levels of N fertilizer application (equivalent to 80, 120, and 180 kg N ha-1 soil) were supplied for wheat growth at both CO2 concentrations. During the continuous 62-d 13CO2 labeling period, elevated CO2 and increased N fertilizer application increased photosynthesized C accumulation in wheat by 14%-24% and 11%-20%, respectively, as indicated by increased biomass production, whereas the C/N ratio in the roots increased under elevated CO2 but declined with increasing N fertilizer application levels. Wheat root deposition induced 1%-2.5% renewal of soil C after 62 d of 13CO2 labeling. Compared to ambient CO2, elevated CO2 increased the amount of photosynthesized C incorporated into soil by 20%-44%. However, higher application rates of N fertilizer reduced the net input of root-derived C in soil by approximately 8% under elevated CO2. For the wheat-soil system, elevated CO2 and increased N fertilizer application levels synergistically increased the amount of photosynthesized C. The pivotal role of plants in photosynthesized C accumulation under elevated CO2 was thereby enhanced in the short term by the increased N application. Therefore, robust N management could mediate C cycling and sequestration by influencing the interactions between plants and soil in agroecosystems under elevated CO2.
Key Words:  C cycling,C sequestration,continuous 13C-enriched CO2 labeling,growing season,isotope composition,N management,wheat tissue biomass
Citation: Zhao Y, Liang C, Shao S, Li J, Xie H T, Zhang W, Chen F S, He H B, Zhang X D. 2021. Interactive effects of elevated CO2 and nitrogen fertilization levels on photosynthesized carbon allocation in a temperate spring wheat and soil system. Pedosphere. 31(1): 191-203.
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