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Geophysical equipment

Electrical potential differences between plants and topsoil

Many soil properties influencing plant growth and yield can be identified and mapped with electrical geophysical methods, which explains recent advances in electrical conductivity method application in precision agriculture. Moreover, our recent studies have shown that soil electrical potentials influence plant growth directly and electrical geophysical methods can be used to monitor plant health (Fedotov and Pozdnyakov, 2001).

Electrical potential differences between soil horizons

The natural electrical potentials (stationary and fluctuating) in soils were studied by our group for last 40 years and the results were summarized and presented on 17th World Congress of Soil Science (Pozdnyakov and Pozdnyakova, 2002). The largest electrical potential differences were observed between soil horizons drastically different in physical and chemical properties. In most soils topsoil has higher electrical potentials than subsoil.

Special instrumentation for soil SP method is needed

solid state Ag-AgCl electrodesLandMapper ERM-02, in addition to electrical conductivity and resistivity measurements also allows non-invasively measure natural electrical potentials in soils and plants when two special non-polarizing electrodes are connected to MN terminals (Figure 3).

Measuring Electrical Potentials with LandMapper ERM-02

Electrical geophysical methods are classified as methods measuring natural electrical potentials of the ground without introducing additional electrical field and methods utilizing artificial electrical or electromagnetic fields to measure soil electrical parameters. Method of self-potential (SP) measures the naturally existing electrical potentials in soils and “bio-potentials” in plant, which are important in agriculture. Despite growing popularity of electrical resistivity/conductivity methods in agriculture, method of self-potential is rarely used.

Seven-step approach for complete near-surface resistivity survey of farmland with LandMapper

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).


Protvino, MOS
55° 44' 34.0548" N, 37° 36' 55.4436" E
United States
42° 52' 48.8676" N, 104° 45' 56.25" W

Table 2. Technical Specifications of LandMapper ERM-02

Table 2. Technical Specifications of LandMapper ERM-02

Range of measurements   ……………………………………….……..    ER= 0.1-1 106 Ohm m

Table 1. Compare LandMapper ERM-01 and ERM-02

Table 1.  Compare LandMapper ERM-01 and ERM-02


LandMapper ERM-01

LandMapper ERM-02

Electrical Resistivity, Ohm m

LandMapper ERM-02 – three parameter geophysical instrument

The newest model, LandMapper ERM-02, can automatically output EC or ER, accepts four-electrode probes of any configuration, including dipole-dipole and rectangular probes, reaches down to 10 m depth in most soils and stores up to 999 resistivity values in non-volatile memory. Also, ERM-02 model can be used to measure natural electrical potentials in soils, plants and other media with two non-polarizing electrodes (Figs. 2&3).

Introducing LandMapper ERM-01

To address those applications Landviser, LLC has developed and commercialized first model of LandMapper ERM-01 in 2004, which was able to measure electrical resistivity with central-symmetric four-electrode probes of Shlumberger and Wenner configurations to the depth of five meters. Device became popular among agricultural researchers in USA and Europe, and was tested for fast mapping and monitoring of agricultural and horticultural lands (Pozdnyakova et al., 2004; Paillet et al., 2010; Duncan et al., 2008; Carrow and Duncan, 2004).

LandMapper ERM-02: handheld meter for near-surface electrical geophysical surveys

published in December, 2010 issue of FastTIMES, online peer-reviewed journal of EEGS. To cite this publication use:FastTIMES dec 2010 Agriculture: A budding field in Geophysics

Golovko, Larisa, Anatoly Pozdnyakov, and Antonina Pozdnyakova. “LandMapper ERM-02: Handheld Meter for Near-Surface Electrical Geophysical Surveys.” FastTIMES (EEGS) 15, no. 4 - Agriculture: A Budding Field in Geophysics (December 2010): 85–93.


On-the-go sensors, designed to measure soil electrical resistivity (ER) or electrical conductivity (EC) are vital for faster non-destructive soil mapping in precision agriculture, civil and environmental engineering, archaeology and other near-surface applications. Compared with electromagnetic methods and ground penetrating radar, methods of EC/ER measured with direct current and four-electrode probe have fewer limitations and were successfully applied on clayish and saline soils as well as on highly resistive sandy soils, such as Alfisols and Spodosols. However, commercially available contact devices, which utilize a four-electrode principle, are bulky, very expensive, and can be used only on fallow fields. Multi-electrode ER-imaging systems applied in deep geophysical explorations are heavy, cumbersome and their use is usually cost-prohibited in many near-surface applications, such as forestry, archaeology, environmental site assessment and cleanup, and in agricultural surveys on farms growing perennial horticultural crops, vegetables, or turf-grass. In such applications there is a need for accurate, portable, low-cost device to quickly check resistivity of the ground on-a-spot, especially on the sites non-accessible with heavy machinery.

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