Ammonia-oxidising microorganisms play a central role in regulating N2O production in dryland soils. However, the spatial variation in the contribution of the nitrification pathway (NP) to total N2O emissions, as well as its associations with ammonia-oxidising archaea (AOA) and bacteria (AOB), remains insufficiently characterised. Using an 11-year tillage experiment (zero [ZT] and chisel plough [CPT] vs. conventional plow tillage [PT]), we quantified the NP contribution to total N2O emissions and elucidated the respective roles of AOB and AOA in dryland agroecosystems. Long-term implementation of conservation tillage significantly reduced the proportion of nitrification-derived N2O in total N2O emissions. Compared to PT, NP-associated N2O fluxes under CPT and ZT were reduced by 59.32% and 34.78%, respectively. In addition, during the peak N2O emission period, ZT and CPT decreased the AOA : AOB ratio while increasing the richness, diversity, and evenness of AOA and AOB communities. The contribution of deterministic assembly processes within the AOA community progressively increased with greater tillage intensity. By contrast, during the peak N2Oemission period, deterministic assembly exerted a stronger imprint on AOB communities under conservation tillage than under plough-tilled soil. Partial least squares path modelling identified soil moisture at 10 and 20 cm depths, NO3 - concentration, soil pH, AOA abundance and the AOA : AOB ratio as the major variables regulating NP-derived N2O emissions. Long-term conservation tillage significantly decreased NP-derived N2O emissions by lowering the AOA : AOB ratio and enriching keystone taxa within the microbial co-occurrence network. These results provide a promising conservation tillage strategy that effectively improves soil nitrogen retention, enhances the basic soil fertility and maintains the sustainable productivity in dryland farmland.