Salinity, sodicity, acidity and phytotoxic concentrations of chloride in subsoils are major constraints to crop production in many soils of north-eastern Australia because they reduce the ability of crop roots to extract water and nutrients. Subsoil constraints vary both spatially across the landscape and within soil profile. Identification of spatial variability of these constraints and appropriate management options will allow farmers to manage this variation for profitable outcomes. We used electromagnetic (EM38) induction, yield maps and soil samples to map out suspected subsoil constraints on five farms. Soil physical and chemical properties to 1.5 m depths, showed that soil chloride and water were significantly correlated with EM measurement (ECa; apparent electrical conductivity) weighted for either soil profile or sensor in the fields at Goondiwindi, Roma and Moree. As a result, we found large areas showing substantial subsoil constraints. Furthermore, these relationships became stronger as the soil depth increased. Also, at these fields, strong negative relationship was found between ECa values and yield maps. At field in Narrabri, soil clay content and bulk density showed strong relationships with ECa values, while at field in Biloela, none of the soil property measured in this study showed significant relationship with ECa, thus requires further investigation. Across all fields we studied, strong linear relationships were obtained between ECa values and soil chloride, electrical conductivity, soil water, and clay contents. Therefore, it may be feasible to develop relationships between ECa and subsoil constraints that are applicable across a wide range of soil and climatic conditions.