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Chinese Journal of Applied Ecology ›› 2018, Vol. 29 ›› Issue (8): 2470-2476.doi: 10.13287/j.1001-9332.201808.031

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Effects of carbon and nitrogen additions on soil organic C, N, P contents and their catalyzed enzyme activities in a grassland.

LI Huan-ru1,2,3, ZHU Ying1,2, TIAN Ji-hui4, WEI Kai1, CHEN Zhen-hua1, CHEN Li-jun1*   

  1. 1Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China;
    2 University of Chinese Academy of Sciences, Beijing 100049, China;
    3 Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China;
    4 South China Agricultural University, Guangzhou 510642, China.
  • Received:2017-10-30 Online:2018-08-20 Published:2018-08-20
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (41771333, 41701344)

Abstract: Soil organic C, N, P contents and their catalyzed enzyme activities play an important role in maintaining and supplying energy and nutrient in grasslands. There is no consensus on the effects of N deposition on soil organic nutrients and enzyme activities in grassland ecosystems. It remains unclear whether C addition will retard the negative effects of N deposition. We carried out an experiment in Hulun Buir grassland of Inner Mongolia to examine the effects of C and N additions on soil organic C, N, P and relative enzyme activities after three years treatments. The experiment was conducted with N treatments at five levels (0, 25, 50, 100 and 200 kg·hm-2·a-1) and with C treatments at three levels (0, 250 and 500 kg·hm-2·a-1). The results showed that higher levels of N addition significantly decreased dehydrogenase (DHA) and β-1,4-N-acetylglucosaminidase (NAG) activities by 22.3% and 12.5%, respectively. Nitrogen addition had no significant effect on soil organic N and decreased the organic C and P contents by 6.6% and 14.5%, respectively. High C addition significantly increased DHA, β-glucosidase (BG) activities and increased soil organic N and organic P by 15.1%, 12.2%, 1.9%, 2.6%, respectively. The results suggested that continuous N inputs inhibited microbial activities and caused losses of soil organic C and organic P. Carbon addition could enhance microbial activities and promote the secretion of enzymes and increase soil organic N and P. The combined C and N addition could play an important role in maintaining the balance and supply of soil C, N, and P in grassland ecosystem.