Dr. Larisa Golovko (President of Landviser, LLC) will be presenting "Geophysical Methods of Electrical Resistivity and Self-Potential in Agriculture" in first of 

Agricultural Geophysics Webinar Series: "Application of Geophysical Methods to Agriculture: Methods Employed"

A live webinar on the application of geophysics to agriculture will be offered on:

Tuesday, February 18, 2014, from 3pm - 4:30pm EST
(2:00 - 3:30 CST, 1:00 - 2:30 MST, 12:00 - 1:30 PST)

This first in a series of agricultural geophysics webinars will focus on the near-surface geophysical methods presently being used for agricultural purposes, which include resistivity, self-potential, electromagnetic induction, ground penetrating radar, dielectric sensors, VIS/NIR/MIR spectrometry, gamma ray spectrometry, mechanical soil compaction sensors, and ion selective potentiometry. Five presenters will provide a short overview of agricultural geophysical methods during the first 30 minutes of the webinar. The last hour of the webinar will be devoted to a panel discussion with the presenters, who will answer questions from the audience.

Location

Landviser, LLC is offering advanced equipment for deep electrical tomography - Siber-48 - manufactured by KB Electrometry, Ltd in Novosibirsk, Russia. Since 2012 they started to produce modificated version of "SibER". New device has new safer body, powerfull generator (inject current up to 2A), provide more stable and faster measurments.

Price of the system ordered through us is the same as listed on Nemfis.ru. Registered users can view complete price of the SibER-48 and SibER-64 equipped with two standard 5-m spaced cables in current catalog. Custom spacing of electrode connectors on the cables is also available per request.

Please, request your personalized quotation from us: info@landviser.com or call 1-609-412-0555 / 1-888-306-LAND. The system is shipped worldwide from Russia, shipping costs will vary. See specification table at the bottom of this page on estimated weight of the system and components.

Update: Full PDF of the paper is now available!

Electrical resistivity of cultivated sandy soils of humid areas is a complex characteristic based on three fundamental properties of soil matrix, such as soil texture, total organic matter (carbon content) and cation exchange capacity (CEC). Relationship of electrical resistivity (ER) with those properties has been approximated with exponential equation ER=a*exp(-b*x), where x is any of the properties above. The correlation coefficients for ER as function of CEC, texture, or organic matter were between 0.82 and 0.91 for the soils of Klin-Dmitrov watershed near Moscow and Kirov, which suggests their applicability for other humid areas. We present a new approach to approximate exponential relationship ER=a*exp(b*x) with a linear “piece-wise” function based on the age of cultivation for each field.This approach was used to develop management zones based on ER to separate uniform areas of similar organic matter, CEC and clay content. Those basic properties are the foundation of soil fertility in humid areas. They influence biomass and bioactivity of soil microorganisms, thus the exponential relationship between ER and soil microorganisms was also observed. The approach based of electrical resistivity or conductivity was used to evaluate fertility and degree of cultivation of sandy soils in humid areas and for detail soil mapping and delineation of management zones in adaptive precision agriculture. The field and laboratory electrical geophysical methods are recommended for quick and accurate soil mapping and management in sustainable farming.

*at SAGEEP 2013, March 17-21 in Denver, CO, Larisa Golovko, Ph.D. will also present "Basic Theory of Measuring Electrical Resistivity, Conductivity and Self-Potential in Soils and Plants" with LandMapper ERM-02 and other commercially available geophysical equipment at post-conference workshop "Agricultural Geophysics: Theory and Methods".

Cite this presentation as: Anatoly Pozdnyakov, P.I. Eliseev, Larisa Golovko, Lev A. Pozdnyakov, Maria S. Dubrova, and E.P. Makarova. “Evaluating Cultivation Level of Sandy Soils in European Russia with Electro-geophysical Methods.” In New Views of the Earth. Denver, CO: Environmental and Engineering Geophysical Society, 2013. http://www.eegs.org/AnnualMeetingSAGEEP/SAGEEP2013/SessionsAbstracts.aspx

Locations

Guest post by Dr. Leonid Anisimov, Principal Scientist of Lukoil-Engineering, Volgograd, Russia. VolgogradNIPImorneft – scientific center of the LUKOIL Oil Company for the South Volga, Caspian Region and Middle East.

Shalow gas accumulations in shale deposits are unconventional energy resources. However those are hazardous objects for drilling especially in the offshore areas.
Seismic is a principal instrument to detect shallow gas pockets but electromagnetic methods may have advantage. The presentation below shows principal geography and techniques for detection and development of shale gas fields. A pilot project of Landviser LLC in using VES for monitoring accumulation and release of methan in peat bogs of Eastern Siberia is attached.

Locations

The valley landscapes of humid areas are dominated with peat soils of various origins, which become the most productive soils after the proper drainage and cultivation. The high fertility and proximity to water make peat soils the most desirable for vegetable production. However, these soils are also subject to quick degradation during agricultural usage. Excess drainage increases the unproductive decomposition and mineralization of peat and can cause spontaneous ignition of peat soils, whereas little or no drainage can be non-sufficient for normal agricultural practices. Therefore, drainage design and the following agriculture practice on peat soils should be based on careful studies of the peat soil genesis and hydrology of the areas.

 Method VES is suitable for detection the resistivity in different soil and geological strata without digging or boring. Usually, peat shows not much difference in electrical properties along the profile. Water content of cultivated peat soils is close to the field capacity during the whole growing season.

The groundwater table rises steadily in the delta Volga, where Astrakhan’ city is located because of irrigation and rising of the Caspian Sea level. The highly saline groundwater enhances secondary salinity in the area. The groundwater caused visible destruction of more than 20% of the buildings in Astrakhan’ city. Natural hazardous groundwater condition in delta Volga was further aggravated in the urban areas by the uncontrolled leakage from the canals and plumbing pipes.

The methods of vertical electrical sounding (VES) and non-contact electromagnetic profiling (NEP) were tested in 1995 for detail outlining of the groundwater table within the representative part of Astrakhan’ city. The study area was located in the center of Astrakhan’ with a large change of elevation, which induced a high variation of groundwater table within the area.

Profiles of alluvial soils in delta Volga consist of thin layers of silt, clay, and sand. However, only water and salt content distributions within the soil profile cause considerable differentiation of the electrical resistivity in these soils. The soil profile can be generally divided into the top unsaturated layer with high resistivity and the bottom layer saturated by saline groundwater with low resistivity. Considering high distinction in electrical resistivity between unsaturated and saturated zones, the VES method was applied for detection of groundwater table. With the 1-D computer interpretation of the VES data the transition between top layer with high resistivity and bottom layer with low resistivity (i.e. groundwater table) was determined accurately. Compared with the groundwater tables measured in wells, the relative errors of the VES estimation were from 3 to 13%.

The technique and procedure described here can be performed with LandMapper ERM-01 or ERM-02 (set in resistivity mode). The electrode spacings provided in this example are identical to Landviser's supplied "big manual VES" cable set made to measure 16 layers of topsoil down to approximately 9 m. The worksheet for pre-set electrode spacings in such cable re-calculating measured resistivities to 1D VES profile can be downloaded as Manual 1D VES workbook (MS Excel format).

Other electrode spacings are possible for custom-made cable arrays to reach deeper profiles. For example, we developed and tested with LandMapper a 60m-long cable, measuring down to ~ 20 m for one custom hydrology project. 

This manual VES technique is most convenient to use with three people. Follow step-by-step instructions below. If you need further help, do not hesitate to contact Landviser, LLC @ +1-609-412-0555 or info@landviser.com. Register on our site and download 7 related publications and software!

Locations

Water and salt content distributions within the soil profile are the main properties causing considerable variations in electrical resistivity. In arid areas, the water content and salt distributions are determined mainly  by the saline groundwater, rather then by precipitation. 

The soil profile is divided into a top unsaturated layer with high resistivity and a bottom layer saturated by saline groundwater with low resistivity. Considering large differences in electrical resistivity between the unsaturated and saturated zones, the VES method was applied to detect the saline groundwater level. 

Location

Water and salt content distributions within the soil profile are the main properties causing considerable variations in electrical resistivity or conductivity.  Since the evaporation in the arid areas (Astrakhan, Russia) is about five times higher than the precipitation, the water content and salt distributions are determined mainly by the saline groundwater.

The differentiation of salinity in the unsaturated zone of the soil profiles was revealed by small fluctuations of electrical resistivity in upper part of the VES profiles. We thoroughly interpreted the VES results to estimate the layers with different electrical conductivities (EC) for 12 soil profiles. The total salt content was measured in soil samples collected from the layers of the profiles as shown in Table (columns 1 and 2) for one example profile.