Geo-electrical survey on the soil of an apricot orchard grown under semi-arid conditions

A geo-electrical survey, combined with direct measurements on soil samples, was performed to study spatial relationships among electrical resistivity (ρ), hydro-pedological parameters, and root characteristics. The trial was carried out on the soil (WRB: Haplic Regosols) of an apricot orchard grown in a semi-arid climate, cover-cropped, and micro-irrigated. Three 2D geo-electrical tomographies were performed in the Wenner and dipole-dipole array (electrode spacing of 25 cm). Soil samplings were carried out from vertical trenches excavated directly below the respective geo-electrical profiles. Direct measurements of bulk density, grain size distribution, volumetric water content (θ), electrical soil conductivity (EC1:1, EC1:2.5), stone content, and root biomass were performed on the soil samples in situ and in the laboratory. Hydraulic saturation (HS) and soil porosity (Φ) were also calculated. Statistical analyses performed between the geo-electrical signals (ρ) and soil data showed a univariate relationship with EC1:2.5. Multivariate relationships among ρ, EC1:1, and HS were also found. The significant relationship found between  and soluble salt content proves the usefulness of the geo-electrical technique in the medium-scale assessment of the spatial variability of salt accumulation processes in heterogeneous tree orchard systems