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.

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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

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I had tested a small gadget called GPS logger from Columbus Visiontac. Complete product name-description is:

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Despite numerous EC-mapping case studies conducted in many countries, only a few studies have demonstrated a complex approach to electrical geophysical site survey. In most studies only one technique of EC-mapping, either EM, GPR or four-electrode method was employed. This is understandable since most commercially available EC/ER measuring equipment operate in limited range of resistivities and depths (1-2 manufacturer-set depths are typical).

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Establishments of orchards and vineyards are long-term and money-intensive, but highly pay-off projects. This study allowed developing procedure for incorporating geophysical survey data into recommendations of usage skeletal soils under orchards. Geophysical methods of electrical resistivity, such as VES and four-electrode profiling provided the information about spatial distributions of stones in skeletal soils.  The resistivity of rocks or stones is much higher (about 10⁴-10¹² ohm m) than the resistivity of soil horizons with any texture. Therefore, high resistivity will indicate the presence of stones in soil profiles.

Study was conducted on skeletal soils (Paleoxerolls and Lithic Xerorthents) formed on carbonate-cemented marine deposit, limestone, or pebbles of alluvial origin in western part of Crimea Peninsula, Ukraine. The stone content varied from 2 to 90% of fragments coarse than 2 mm by volume and stony layers occurred in soil profiles at the depth as shallow as 12 cm.

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Task on hand: estimate salinity level on fields planned for rice next year. Six fields with total area of 322 acres were selected by farmer.

Equipment on hand: two LandMappers with different size probes attached (measuring electrical conductivity (EC) down to ~ 8” and 18”), Columbus GPS data-logger, all-road vehicle or “Mule”. Three people: farmer driving a '”mule” and recording data on paper, one person measuring with Landmapper at 18” depth, other person measuring EC with LandMapper to 8” depth and recording POI or way points with GPS. Results: 30 points recorded in less than 1.5 hour (including about 45 min break to wait out the rain). EC in the field varied from 5 mS/m to 106 mS/m on surface; and from 19 mS/m to 400 mS/m in deeper layer.

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