J Plant Ecol ›› 2022, Vol. 15 ›› Issue (5): 897-910 .DOI: 10.1093/jpe/rtac006

• Research Articles • Previous Articles     Next Articles

The response of soil respiration to different N compounds addition in a saline–alkaline grassland of northern China

Huajie Diao1,2,3,4, Xiaopeng Chen1,3,4, Ge Wang1,3,4, Qiushi Ning2, Shuya Hu2, Wei Sun5, Kuanhu Dong1,3,4,* and Changhui Wang1,2,3,4,*   

  1. 1 College of Grassland Science, Shanxi Agricultural University, Taigu 030801, China, 2 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, 3 Shanxi Key Laboratory of Grassland Ecological Protection and Native Grass Germplasm Innovation, Shanxi Agricultural University, Taigu 030801, China, 4 Youyu Loess Plateau Grassland Ecosystem Research Station, Shanxi Agricultural University, Taigu 030801, China, 5 Institute of Grassland Science, Key Laboratory of Vegetation Ecology of the Ministry of Education, Northeast Normal University, Changchun 130024, China

    *Corresponding author. E-mail: dongkuanhu@sxau.edu.cn (K.D.); wangch@ibcas.ac.cn (C.W.)
  • Received:2021-06-24 Revised:2021-07-31 Accepted:2021-10-24 Online:2022-01-16 Published:2022-09-01

Abstract:

The increase in atmospheric nitrogen (N) deposition has profound effects on soil respiration (SR). However, the responses of SR to the addition of different N compounds, particularly in saline–alkaline grasslands remain unclear. A 3-year controlled field experiment was conducted to investigate the responses of SR to different N compounds (NH4NO3, (NH4)2SO4 and NH4HCO3) during the growing seasons in a saline–alkaline grassland located in the agro-pastoral ecotone of northern China. Our results demonstrated that SR showed a bimodal pattern and a significant interannual difference that was regulated by air or soil temperature and precipitation. Nitrogen addition had a significant effect on SR, and the effect of N addition on SR varied yearly, which was related to seasonal precipitation. The mean SR across 3 years (2017–2019) was increased by 19.9%, 13.0% and 16.6% with the addition of NH4NO3, (NH4)2SO4 and NH4HCO3, respectively. The highest effect of NH4NO3 addition on SR across 3 years was ascribed to the highest aboveground net primary production, belowground net primary production (BNPP) and soil NO3 concentrations. SR (C loss) was significantly increased while plant productivity (C input) did not significantly change under NH4HCO3 addition, indicating a decrease in C sequestration. In addition, BNPP was the main direct factor influencing SR in this saline–alkaline grassland, and soil salinization (e.g. soil base cations and pH) indirectly affected SR through soil microorganisms. Notably, NH4NO3 addition overestimated the response of SR to N addition, and different N compounds should be considered, especially in saline–alkaline grassland.

Key words: nitrogen compounds, soil respiration, soil microorganism, plant biomass, saline–alkaline grassland

摘要:
不同形态氮化合物添加对中国北方盐渍化草地土壤呼吸的影响
持续增加的氮沉降在提高陆地生态系统生产力的同时也会对土壤微生物产生显著影响;土壤呼吸由植物根系呼吸和土壤微生物呼吸组成,因此影响植物生产力和微生物的因子都会影响到土壤呼吸。以往氮富集对土壤呼吸的研究主要在土壤中性的草地生态系统开展,而对于盐渍化草地土壤呼吸是如何响应氮沉降的研究尚不多见,这限制了全球变化陆地生态系统土壤呼吸模型预测的准确性和完整性。本研究以中国北方农牧交错带盐渍化草地为研究对象,通过3年(2017–2019年)野外监测土壤呼吸及相关生物和非生物因子的变化,探讨了不同形态氮化合物添加(NH4NO3、(NH4)2SO4和NH4HCO3)对盐渍化草地土壤呼吸的影响及其调控机制。结果表明:(i)土壤呼吸受大气温度、土壤温度及降水的调控,呈现双峰的季节动态变化趋势和显著的年际差异。(ii)与对照相比,经过3年的处理,土壤呼吸在NH4NO3、(NH4)2SO4和NH4HCO3添加处理下分别提高了19.9%、13.0%和16.6%。(iii)NH4NO3添加对土壤呼吸较高的促进作用与较高的地上生物量、地下生物量以及土壤NO3含量有关。(iv)在NH4HCO3 添加处理下,土壤碳排放(土壤呼吸)显著增加而碳输入(净生产力)无显著改变,表明NH4HCO3添加会降低土壤碳的固持。(v)净地下生产力(BNPP)是盐渍化草地土壤呼吸的最主要调控因子,并且土壤阳离子浓度和pH值通过影响土壤微生物间接影响土壤呼吸。上述研究结果表明,草地添加NH4NO3的研究高估了氮沉降对土壤呼吸的影响,并且在碳循环预测模型中应充分考虑盐渍化草地土壤碳动态。


关键词: 氮化合物, 土壤呼吸, 土壤微生物, 植物生产力, 盐渍化草地