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Acta Prataculturae Sinica ›› 2016, Vol. 25 ›› Issue (12): 44-52.DOI: 10.11686/cyxb2016231

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Dynamics of soil carbon and nitrogen sequestration and sequestration rate following long-term fencing of grasslands and abandoned farmlands

LI Jian-Ping1, CHEN Jing1, XIE Ying-Zhong1, 2, *   

  1. 1.School of Agriculture, Ningxia University, Yinchuan 750021, China;
    2.Breeding Base of State Key Laboratory for Preventing Land Degradation and Ecological Restoration, Ningxia University, Yinchuan 750021, China
  • Received:2016-05-31 Revised:2016-08-05 Online:2016-12-20 Published:2016-12-20

Abstract: Determining the effects of different vegetation restoration measures on soil organic carbon (SOC) and total soil nitrogen (TSN) can increase our understanding of carbon and nitrogen cycling in terrestrial ecosystems, which play important roles in moderating the global greenhouse effect. In this study, we evaluated carbon and nitrogen cycling in fenced grassland and abandoned farmland on the Loess Plateau, using grazed grassland and alfalfa farmland as the control and reference sites, respectively. We analyzed SOC storage, TSN storage, SOC sequestration, TSN sequestration, and their sequestration rates in grassland that had been fenced for 14 years and in abandoned farmland (0-300 cm soil depth). The results showed that SOC storage was significantly increased in 14-year-fenced grassland and abandoned farmland, compared with the reference and control sites. The mean values of SOC storage were similar in 14-year-fenced grassland and abandoned farmland; at 0-200 cm depth soil, STN storage in 14-year-fenced grassland was not significantly higher than that in grazed grassland, but at 0-300 cm soil depth, the STN storage was significantly higher in the 14-year-fenced grassland than in abandoned farmland (P<0.05). The amount of SOC sequestration and its rate were significantly higher in abandoned farmland than in fenced grassland. The SOC sequestration in abandoned farmland was almost completely limited to the 0-140 cm depth soil. At 0-100 cm soil depth, the amount of STN sequestration and its rate were significantly higher in abandoned farmland than in fenced grassland, but at 0-300 cm soil depth, the amount of STN sequestration and its rate were significantly lower in abandoned farmland than in fenced grassland. Therefore, 14 years of fencing of grassland and abandoned farmland could significantly increase SOC, but not TSN storage. Compared with fenced grassland, abandoned farmland had a higher SOC sequestration capacity and sequestration rate.