This dataset contains field measurements of the electrical conductivity of saturated paste extracts (ECe) used for cropland soil salinity mapping in two contrasting salt-affected agricultural regions of China: the Manas River Basin (MRB), representing an inland arid irrigated oasis, and the Yellow River Delta (YRD), representing a coastal delta environment. A total of 2,244 topsoil samples (0–20 cm) are included, comprising 1,250 samples from the MRB and 994 samples from the YRD. The dataset supports the study entitled “Process-aware residual correction for 10 m resolution cropland ECe mapping in oasis and coastal delta regions.” ECe values are reported in dS m⁻¹.