A Vertical Electrical Sounding Method for Agricultural Soil Survey

Soil survey of agricultural lands requires a quick and, possibly, non-disturbing estimation of numerous soil properties, such as salinity, texture, stone content, groundwater depths, and horizon sequences in soil profiles. Most of geophysical methods currently used in agriculture, such as electromagnetic (EM conductivity) and four-electrode (resistivity) mapping are non-disturbing, but fail to provide information about soil property variations within a profile and at the best arrangement measure EC/ER at only two distinct soil depths. A method of vertical electrical sounding (VES) adapted by us to use with LandMapper ER measuring hand-held device can distinguish differences in electrical resistivity or conductivity at the multiple (10+) layers in soil profiles. These differences reveal the changes in soil properties within the profiles. The paper shows various applications of the modified geophysical VES method in agricultural soil survey. Information is provided for the VES array assembly, field measuring procedure and interpretation of sounding results. The applications of the method included soil morphology evaluation and soil mapping, assessment of stone content in soil, estimation of the groundwater table and salinity layers in the soil profile, monitoring of drying and defrosting in soils; and outlining hydrocarbon pollutant distributions in soil profiles. This modified VES method has also a great potential for other soil applications.