Preceding crops may reduce denitrification potential and enhance ammonium assimilation pathways

Background: Soil microorganisms are pivotal to nitrogen (N) cycling in croplands, yet how preceding crops modulate their functional profiles remains unclear. Objective: This field study aimed to quantify the effects of barley (BT) and rapeseed (RT) preceding crops (vs. no preceding crop, CK) on soil microbial functions and N-metabolic pathways in tobacco fields. Results: < 0.01). Conclusion: Our findings demonstrate that barley and rapeseed preceding crops enhance microbial richness and activity, thereby inhibiting denitrification and promoting N fixation via altered ammonium-N dynamics.