Soil spatial variability influences crop productivity and is increasingly assessed using electromagnetic induction technologies. This study investigated the spatial and temporal variability of EM38-derived apparent soil electrical conductivity at 0.5 m and 1.0 m depths and its relationship with maize (Zea mays L.) grain yield under contrasting tillage systems in an irrigated production environment in eastern Hungary during the 2024 and 2025 growing seasons. Conductivity measurements were collected during vegetative and cob formation stages using an EM38 sensor operated in vertical dipole mode. Relationships between ECa and maize yield were examined using descriptive statistics, correlation analysis, and analysis of variance. Significant differences in maize yield were observed among tillage systems in both seasons, with strip tillage producing lower yields than winter ploughing and ripping tillage (p < 0.05). Strong positive correlations were found between conductivity measurements at 0.5 m and 1.0 m depths (r = 0.807–0.928, p < 0.001), indicating consistent spatial conductivity patterns across the soil profile. However, ECa was not significantly correlated with final maize grain yield in either season. These results demonstrate that EM38 sensing effectively characterises soil spatial variability but has limited value as a stand-alone predictor of maize yield under uniformly irrigated conditions.