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NH4NO3 N-addition overstates steppe microbe effects
In Inner Mongolian steppe, acidic NH4NO3 and (NH4)2SO4 shifted soil bacteria and carbon-gene profiles more than urea or NH4HCO3, so NH4NO3-only experiments can overestimate real N-deposition effects.
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What shortcut do >50% of N-deposition experiments use?
Adding NH4NO3 to mimic deposition.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Where was the experiment?
Eurasian/Inner Mongolian steppe.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Which N forms were compared?
NH4NO3, (NH4)2SO4, urea, slow-release urea, NH4HCO3, plus control.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Which compounds most acidified soil and cut roots?
NH4NO3 and (NH4)2SO4 (plus NH4HCO3 for roots; urea also dropped pH).
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
How did acid N change bacterial phyla?
More Actinobacteria and Alphaproteobacteria; fewer Acidobacteria and Chloroflexi.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Main factor correlating with bacterial composition?
Soil NH4+-N content.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Actinobacteria response: NH4NO3 vs NH4HCO3?
24.97% vs 9.68% increase.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Did plant community composition change?
No significant PERMANOVA effect.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
What carbon genes rose under acid N?
Degradation genes for aromatics, phenolics, cellulose, lignin, lipids, polysaccharides.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Authors’ warning about NH4NO3-only studies?
They likely overestimated microbial diversity/function effects in this steppe.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified
Ambient deposition at the site?
Less than 1.5 g N m−2 yr−1.
Source: Nitrogen deposition experiment mimicked with NH<sub>4</sub>NO<sub>3</sub> overestimates the effect on soil microbial community composition and functional potential in the Eurasian steppe · DOI · quote verified