Nitrogen cycle
NH4NO3 N-addition overstates steppe microbe effects
Open access · cc by · source: Europe PMC
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.
Key findings
Only acid N salts clearly acidified soil, raised NH4+, cut belowground biomass, and shifted bacteria (more Actinobacteria/Alphaproteobacteria, fewer Acidobacteria/Chloroflexi) plus recalcitrant-C genes. NH4NO3 raised Actinobacteria 24.97% versus 9.68% for NH4HCO3.
Methodology
Authors applied control, NH4NO3, (NH4)2SO4, urea, slow-release urea, and NH4HCO3 in a Eurasian steppe (four replicates) and compared plant biomass, soil chemistry, 16S composition, and microbial functional genes.
Limitations
A single-steppe, multi-compound addition is not a full map of atmospheric N speciation everywhere; plant community composition did not shift even where microbes did.
How this study connects
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