ABSTRACT Microbial necromass‐mineral interactions are vital for soil organic carbon (C) persistence, but their response to concurrent climate and fertilization legacies in croplands remains unclear. Using six long‐term field sites (27–38 years) across a pronounced aridity gradient, we show that stabilization of microbial necromass is coupled with short‐range ordered (SRO) minerals in humid zones (aridity index, AI < 1.3). In arid zones (AI > 1.3), this correlation strongly weakens, challenging the universality of SRO‐associated C paradigms. While aridity controls mineral weathering and SRO abundance, we showed that long‐term fertilization can supersede aridity‐driven constraints on necromass C accrual. Spatial mapping of 6060 in situ μ‐FTIR spectra revealed reduced organic C transformation in outer aggregate rims under aridity, aligning with diminished microbial processing and a consequent weakening of necromass‐SRO associations. Our findings establish soil moisture as a critical regulator of fertilization‐induced ecological memory in mineral‐necromass interactions, urging climate‐tailored practices to sustain soil C resilience in water‐limited ecosystems under global aridification.