Nitrogen deposition experiment mimicked with NH(4)NO(3) overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe

BACKGROUND: The nitrogenous compound deposited from the atmosphere to the soil is complex, but most field experiments mimic nitrogen deposition with the acid NH(4)NO(3) alone. 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 NH(4)NO(3) and (NH(4))(2)SO(4), and non-acidic urea, slow-released urea and NH(4)HCO(3) in a temperate steppe, and quantified soil microbial taxonomic and functional gene composition with amplicon sequencing and shotgun metagenomics, respectively. RESULTS: While NH(4)NO(3) and (NH(4))(2)SO(4) significantly altered the soil microbial taxonomic and functional composition as well as their carbon decomposition potential, the other three compounds had smaller effects. CONCLUSION: Our results suggested that previous nitrogen deposition experiments mimicked with NH(4)NO(3) or (NH(4))(2)SO(4) alone may have overestimated the effect on biodiversity and ecosystem functions in the Eurasian steppe and similar ecosystems affected by mainly nonacidic nitrogen deposition. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40793-022-00441-1.