Environmental determinants of spatial-temporal variability in ammonia oxidizing microorganisms across diverse Chinese agricultural soils.

Numerous studies investigated the variation of soil ammonia oxidizing microorganisms along the geographic distance, but few highlighted the associated influence of agricultural practices on ammonia oxidizing communities and functions. To make up this gap, we determined the variation of ammonia-oxidizing archaea (AOA), bacteria (AOB), and soil nitrification within eight typical agricultural plots across China. The current study revealed significant variations in soil potential nitrification rates (PNRs) and the diversity and composition of AOA and AOB communities across various plots. Spearman correlation analysis revealed a significant link between soil PNRs and alpha diversity, specific AOA and AOB taxa, but no significant correlation was found with amoA gene abundance. Structural equation modeling and canonical correspondence analysis showed that factors like MAT, clay content, CEC, and soil carbon and nitrogen levels significantly influenced the diversity and composition of AOA. In contrast, AOB were more significantly impacted by soil pH and carbon- and nitrogen-related nutrients, but less associated with MAP and soil clay content. Notably, soil PNRs were found to be closely linked to AOB diversity, soil pH, and ammonium nitrogen (NH4N) levels. This research highlights the contributing role of AOB group in soil nitrification and the related driving factors from agricultural practices.