Soil Electrophysics as a New Methodology for Soil Survey.

New approach to soil survey and mapping was developed which utilized broad range of electrical geophysical methods and technologies. Geophysical methods measuring electrical conductivity (EC) and resistivity (ER) have unique importance for soil survey, since only those methods can provide information about soil subsurface quickly and non-destructively, without collecting soil samples, and in the range of depths. The complex approach to agronomic electrical soil mapping is outlined below:  vertical electrical sounding (VES) of major soils on the territory of survey; electrical mapping of the territory with 2-5 four-electrode probes sensing specific key depths selected after VES interpretation; preparation of electrical survey maps in GIS; selection of key soil pits on the territory of survey based on electrical maps and measurement of electrical parameters on the walls of soil pits; collection of soil samples from the layers with contrasting electrical parameters; measurements of electrical parameters and conventional chemical/physical properties in soil samples in laboratory and development of the relationships between soil properties and electrical parameters; transformation and interpretation of field soil survey with the support of laboratory tests and pedotransfer functions; verification of electrical survey with detail soil maps obtained with classical methods and evaluation of economical advantage of new non-contact, non-destructive electrical methods.
All electrical geophysical measurements in this approach can be conducted with just one device, LandMapper ERM02, developed specifically for soil research by AstroGroup (Russia) and Landviser, LLC (USA). With proper attachments, Landmapper can measure electrical parameters from soil surface down to 10-15 m in the field as well as in soil pits, lysimeters, small soil and water samples. We verified the electrophysics approach and equipment on major soil types and landscapes of Russia: tundra (Gelisols) soils (Vorkuta), sod-podzolic (Alfisols) soils (Moscow area), chernozems (Mollisols) and dark-grey soils (Bryansk), brown desert (Aridisols) soils (Astrakhan’) during last five years.