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

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