Journal of Geographical Sciences ›› 2020, Vol. 30 ›› Issue (6): 921-934.doi: 10.1007/s11442-020-1762-3

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Effects of land use and cultivation time on soil organic and inorganic carbon storage in deep soils

YU Xia1,2,3, ZHOU Weijian1,2,4,5,*(), WANG Yunqiang1,4,5,7, CHENG Peng1,2,6,7, HOU Yaoyao1,2, XIONG Xiaohu1,2, DU Hua1,2, YANG Ling1,2,3, WANG Ya1,2,3   

  1. 1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS, Xi’an 710061, China
    2. Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi’an AMS Center, Xi’an 710061, China
    3. University of Chinese Academy of Sciences, Beijing 100049, China
    4. Interdisciplinary Research Center of Earth Science Frontier, Beijing Normal University, Beijing 100875, China
    5. CAS Center for Excellence in Quaternary Science and Global Change, Xi’an 710061, China
    6. Open Studio for Oceanic-Continental Climate and Environment Changes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, Shandong, China
    7. Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710049, China
  • Received:2019-09-20 Accepted:2020-03-05 Online:2020-06-25 Published:2020-08-25
  • Contact: ZHOU Weijian E-mail:weijian@loess.llqg.ac.cn
  • About author:Yu Xia (1988–), PhD Candidate, specialized in environmental science. E-mail: yuxia@ieecas.cn
  • Supported by:
    The Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB40000000);National Natural Science Foundation of China(No.41730108);National Natural Science Foundation of China(No.41773141);National Natural Science Foundation of China(No.41573136);National Natural Science Foundation of China(No.41991252);National Research Program for Key Issues in Air Pollution Control(No.DQGG0105-02)

Abstract:

The vertical distribution and exchange mechanisms of soil organic and inorganic carbon (SOC, SIC) play an important role in assessing carbon (C) cycling and budgets. However, the impact of land use through time for deep soil C (below 100 cm) is not well known. To investigate deep C storage under different land uses and evaluate how it changes with time, we collected soil samples to a depth of 500 cm in a soil profile in the Gutun watershed on the Chinese Loess Plateau (CLP); and determined SOC, SIC, and bulk density. The magnitude of SOC stocks in the 0-500 cm depth range fell into the following ranking: shrubland (17.2 kg m-2) > grassland (16.3 kg m-2) > forestland (15.2 kg m-2) > cropland (14.1 kg m-2) > gully land (6.4 kg m-2). The ranking for SIC stocks were: grassland (104.1 kg m-2) > forestland (96.2 kg m-2) > shrubland (90.6 kg m-2) > cropland (82.4 kg m-2) > gully land (50.3 kg m-2). Respective SOC and SIC stocks were at least 1.6- and 2.1-fold higher within the 100-500 cm depth range, as compared to the 0-100 cm depth range. Overall SOC and SIC stocks decreased significantly from the 5th to the 15th year of cultivation in croplands, and generally increased up to the 70th year. Both SOC and SIC stocks showed a turning point at 15 years cultivation, which should be considered when evaluating soil C sequestration. Estimates of C stocks greatly depends on soil sampling depth, and understanding the influences of land use and time will improve soil productivity and conservation in regions with deep soils.

Key words: cultivation time, deep soil, Gutun watershed, land use, inorganic carbon, organic carbon