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Acta Prataculturae Sinica ›› 2018, Vol. 27 ›› Issue (12): 34-44.DOI: 10.11686/cyxb2018024

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Profile distribution and dynamics of soil organic carbon and total nitrogen in the Horqin meadow wetland during the growing season

WANG Xue-qin1, LIU Ting-xi1, 2, *, ZHANG Jun-yi1, WANG Guan-li1, 2, DUAN Li-min1, 2   

  1. 1.Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China;
    2.Inner Mongolia Autonomous Region Key Laboratory of Water Resources Protection and Utilization, Hohhot 010018, China
  • Received:2018-01-15 Revised:2018-03-15 Online:2018-12-20 Published:2018-12-20
  • Contact: E-mail:txliu1966@163.com

Abstract: Wetlands are highly productive ecosystems and serve as an important component of global carbon and nitrogen cycles. To better understand the functions of wetlands, more accurate estimations of soil organic carbon (SOC) and total nitrogen (TN) reserves in these environments are needed. In this study, soil samples were taken down to a depth of 100 cm twice a month from May to October 2016 and in August 2017 to analyze the profile distributions and dynamics of SOC and TN in the Horqin meadow wetland. The contents of SOC and TN, above- and below-ground biomass, and other soil physicochemical properties such as soil pH were determined. Our results showed that: 1) Both SOC and TN contents decreased significantly with soil depth in the surface layer (0-20 cm), but tended to remain relatively stable in the subsurface layer, ranging from 11.9 to 23.5 g·kg-1 and from 0.66 to 1.50 g·kg-1, respectively. 2) The monthly variations in SOC and TN contents were significant (except for TN content in the 40-60 cm layer), and the magnitude of variation first decreased and then increased with soil depth. The variations in SOC and TN densities (0-100 cm) were larger during the whole growing season than among years. The SOC density increased during the whole growing season, and ranged from 15.44 to 20.82 kg·m-2, while the TN density decreased significantly in the early growth period and then tended to remain relatively stable, ranging from 1.01 to 1.16 kg·m-2. 3) There was a significant positive correlation between SOC content and TN content (P<0.01). Vegetation and hydrology were the key factors affecting the distribution and variations of SOC and TN in the Horqin meadow wetland. The Horqin meadow wetland was found to be a potential carbon sink and nitrogen source during the growing season, but the carbon sink potential has not been fully evaluated on an inter-annual scale. The results indicated that grazing should be banned and nitrogen fertilizer inputs should be increased to enhance the wetland’s function.

Key words: Horqin meadow wetland, soil organic carbon, total nitrogen, growth season, groundwater