AbstractBackgroundThe nitrogenous compound deposited from the atmosphere to the soil is complex, but most field experiments mimic nitrogen deposition with the acid NH₄NO₃alone. Thus, whether the acid and non-acid nitrogenous compounds have similar effects on biodiversity and ecosystem functions remains understudied. We mimicked nitrogen deposition with acidic NH₄NO₃and (NH₄)₂SO₄, and non-acidic urea, slow-released urea and NH₄HCO₃in a temperate steppe, and quantified soil microbial taxonomic and functional gene composition with amplicon sequencing and shotgun metagenomics, respectively.ResultsWhile NH₄NO₃and (NH₄)₂SO₄significantly altered the soil microbial taxonomic and functional composition as well as their carbon decomposition potential, the other three compounds had smaller effects.ConclusionOur results suggested that previous nitrogen deposition experiments mimicked with NH₄NO₃or (NH₄)₂SO₄alone may have overestimated the effect on biodiversity and ecosystem functions in the Eurasian steppe and similar ecosystems affected by mainly nonacidic nitrogen deposition.