Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (7): 780-789.DOI: 10.17521/cjpe.2021.0072

Special Issue: 全球变化与生态系统 生态化学计量 微生物生态学

• Research Articles • Previous Articles     Next Articles

Effects of nitrogen addition at different levels on soil microorganisms in saline-alkaline grassland of northern China

YANG Jian-Qiang1, DIAO Hua-Jie2,3,4, HU Shu-Ya4, WANG Chang-Hui2,3,4,*()   

  1. 1College of Life Science, Shanxi Agricultural University, Taigu, Shanxi 030801, China
    2College of Grassland Science, Shanxi Agricultural University, Taigu, Shanxi 030801, China
    3Youyu Loess Plateau Grassland Ecosystem Research Station, Youyu, Shanxi 037200, China
    4State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Bejing 100093, China
  • Received:2021-03-04 Accepted:2021-04-22 Online:2021-07-20 Published:2021-10-22
  • Contact: WANG Chang-Hui
  • Supported by:
    National Natural Science Foundation of China(31770526);National Key R&D Program of China(2017YFA0604802);Research Projects of Shanxi Province’s Doctoral Graduates and Postdoctoral Researchers Working in Shanxi Province(SXBYKY2021052)


Aims Nitrogen (N) availability is an important limiting factor for grassland ecosystem productivity, and soil microorganisms are the main driving factor on soil N transformation. With the increase of atmospheric N deposition, the response of soil microbial characteristics to different nitrogen input levels is still unclear especially in saline-alkaline grassland.

Methods The experiment was conducted in Youyu Loess Plateau Grassland Ecosystem Research Station, Shanxi Province. Eight different nitrogen addition levels were set, which were 0, 1, 2, 4, 8, 16, 24 and 32 g·m-2·a-1, respectively. The Ammonia-oxidizing microorganisms (i.e. ammonia-oxidizing bacteria (AOB) and ammonia- oxidizing archaea (AOA)) abundance, soil bacterial and fungal abundance, as well as soil microbial biomass carbon (MBC) and nitrogen (MBN) content were measured in the growing season (May to September) in 2020 to explore the effects of different levels of N addition on soil microbial characteristics.

Important findings Our results showed that: (1) Sampling month had a significant effect on soil AOB, bacteria, fungal abundance and MBC, MBN content due to the variation in soil temperature and soil water content in the growing season. (2) N addition had a significant effect on soil AOB abundance, while had no effects on soil MBC, MBN content, and bacterial and fungal composition. (3) Higher N addition (24 and 32 g·m-2·a-1) significantly increased the abundance of ammonia-oxidizing bacteria (AOB) on the early growth stage (May to August), while having no effect on late growth period (September). (4) Soil microorganisms were mainly regulated by soil cations concentrations and soil pH values, which explained the variation of soil microorganisms by 21.8% and 17.2%, respectively. We found that soil microorganisms were not sensitive to N addition in saline-alkaline grassland, while AOB showed a significant increase under higher N addition, indicating that higher N addition might promote soil N transformation.

Key words: saline alkaline grassland, nitrogen addition, Ammonia-oxidizing microorganisms, bacteria, fungi