植物生态学报 ›› 2021, Vol. 45 ›› Issue (1): 85-95.DOI: 10.17521/cjpe.2020.0153

• 研究论文 • 上一篇    下一篇

华北盐渍化草地土壤净氮矿化速率对不同水平氮添加的响应

徐小惠1,2, 刁华杰1,3, 覃楚仪4, 郝杰3, 申颜1, 董宽虎3, 王常慧1,3,*()   

  1. 1中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093
    2中国科学院大学, 北京 100049
    3山西农业大学草业学院, 山西太谷 030801
    4武汉大学测绘学院, 武汉 430079
  • 收稿日期:2020-05-15 接受日期:2020-07-17 出版日期:2021-01-20 发布日期:2020-09-03
  • 通讯作者: 王常慧
  • 作者简介:*(wangch@ibcas.ac.cn)
  • 基金资助:
    国家重点研发计划(2016YFC0500703);国家重点研发计划(2017YFA0604802);国家自然科学基金(31872406)

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)

摘要:

对于养分贫瘠的盐渍化草地生态系统, 大气氮沉降如何影响土壤氮循环过程是一个目前尚未解决的问题。该研究在位于华北地区山西省右玉县境内的盐渍化草地建立了一个模拟氮沉降的试验平台, 设置8个氮添加水平, 分别为0、1、2、4、8、16、24、32 g·m-2·a-1 (N0、N1、N2、N4、N8、N16、N24、N32), 生长季5-9月, 每月月初以喷施的方式等量添加NH4NO3。从2017年5月到2019年10月, 运用顶盖PVC管法每月一次进行净氮矿化速率的测定同时计算了净氮矿化速率对不同水平氮添加的敏感性。主要结果表明: (1)高水平氮添加(N16、N24、N32)显著增加土壤无机氮库; (2)该盐渍化草地土壤氮矿化以硝化作用为主, 经过3年氮添加以后, 高氮添加(N24、N32)显著促进了土壤净硝化速率, 并且不同氮添加水平在不同的月份和年份中表现出差异性响应; (3)不同氮添加水平对土壤净氮矿化敏感性的影响在不同降水年份差异显著, 短期低水平氮添加提高了土壤净氮矿化的敏感性, 而高水平氮添加降低土壤净氮矿化敏感性; (4)盐渍化草地土壤净氮矿化速率与土壤温度和水分呈正相关关系, 与土壤pH呈负相关关系。因此, 在当前氮沉降增加的背景下, 北方盐渍化草地土壤氮矿化速率对低氮添加的敏感性较高, 结合氮沉降的特点, 未来模型预测应该同时考虑氮沉降对盐渍化草地的可能影响。

关键词: 氮添加, 盐渍化草地, 土壤净矿化速率, 敏感性, 硝化速率

Abstract:

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