Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (1): 85-95.DOI: 10.17521/cjpe.2020.0153

• Research Articles • Previous Articles     Next Articles

Response of soil net nitrogen mineralization to different levels of nitrogen addition in a saline-alkaline grassland of northern China

XU Xiao-Hui1,2, DIAO Hua-Jie1,3, QIN Chu-Yi4, HAO Jie3, SHEN Yan1, DONG Kuan-Hu3, WANG Chang-Hui1,3,*()   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
    3College of Grassland Science, Shanxi Agricultural University, Taigu, Shanxi 030801
    4School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China
  • Received:2020-05-15 Accepted:2020-07-17 Online:2021-01-20 Published:2020-09-03
  • Contact: WANG Chang-Hui
  • Supported by:
    National Key R&D Program of China(2016YFC0500703);National Key R&D Program of China(2017YFA0604802);National Natural Science Foundation of China(31872406)


Aims The salinized grassland ecosystem has low level of nutrients, and how increasing nitrogen (N) deposition affects N cycling has not been solved yet.
Methods An experimental platform was set up to simulate increasing N deposition in the saline alkaline grassland ecosystem in Youyu County, Shanxi Province, eight levels of N addition were designed, expressed by 0, 1, 2, 4, 8, 16, 24, 32 g·m-2·a-1 (N0, N1, N2, N4, N8, N16, N24, N32). The same amount of ammonium nitrate (NH4NO3) was sprayed at the beginning of each month during the growing seasons from May to September every year. From May of 2017, net N mineralization rate was measured once a month using top-cover PVC cylinders. The experiment has been conducted for three years from 2017 to 2019.
Important findings The results showed that, (1) High N addition levels (N16, N24, N32) significantly increased soil inorganic N pool. (2) Soil N mineralization in the salinized grassland ecosystem was dominated by nitrification. After three years of N addition, high levels of N addition (N24, N32) significantly promoted the rate of soil net nitrification, and different N levels showed different effects in different months and years. (3) The sensitivity of soil net N mineralization to different levels of N addition showed significant difference among three years with different precipitation. Lower N addition improved the sensitivity of soil net N mineralization, while higher N addition reduced the sensitivity of soil net N mineralization. (4) There was a positive correlation between soil net N mineralization rate and soil temperature, water content, and a negative correlation between soil net N mineralization rate and soil pH value. The sensitivity of soil N cycle to N addition was higher at low level of N addition than at high level of N addition in the saline-alkaline grassland of north China. The influence of increasing N deposition on soil N cycle should be considered in process-based models in the future.

Key words: nitrogen addition, saline-alkaline grassland, soil net nitrogen mineralization rate, sensitivity, soil nitrification rate