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References

Bedmar, A.P., and Araguás, L.A., 2002, Detection and prevention of leaks from dams: Taylor & Francis, Exton, PA.

Carrow, R.N., and Duncan, R.R., 2004, Soil salinity monitoring: present and future: Golf course management, no. November, p. 89-92.

Corwin, R., 1990, The self-potential method for environmental and engineering applications: Geotechnical and Environmental Geophysics, Soc. Expl. Geophysics, Tulsa, OK, p. 127-143.

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.

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

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. http://www.landviser.net/webfm_send/69

Abstract

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.

Instrumentation, Electrical Resistivity (Solid Earth Geophysics Encyclopedia)

Our unique LandMapper device was featured in 2nd edition of Solid Earth Geophysics Encyclopedia as the best small scale portable and accurate electrical resistivity/conductivity meter. To cite this publication use:

Loke, M.H., J.E. Chambers, and O. Kuras. “Instrumentation, electrical resistivity.” In Solid Earth Geophysics Encyclopedia (2nd Edition), Electrical & Electromagnetic, Gupta, Harsh (ed), 599–604. 2nd ed. Berlin: Springer, 2011. http://www.landviser.net/webfm_send/76
 

The PDF of the article is attached to this webpage. Continue reading excert from the Encyclopedia....

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Instrumentation, Electrical Resistivity

  • Electrical survey. Mapping subsurface resistivity by injecting an electrical current into the ground.
  • Resistivity meter. An instrument used to carry out resistiv­ity surveys that usually has a current transmitter and volt­age-measuring circuitry.
  • Electrode. A conductor planted into the ground through which current is passed, or which is used to measure the voltage caused by the current.
  • Apparent resistivity. The apparent resistivity is the resistiv­ity of an equivalent homogeneous earth model that will give the same potential value as the true earth model for the same current and electrodes arrangement.
  • Multi-core cable. A cable with a number of independent wires.

Introduction

The resistivity survey method is more than 100 years old and is one of the most commonly used geophysical explo­ration methods (Reynolds, 1997). It has been used to image targets from the millimeter scale to structures with dimensions of kilometers (Linderholm et al., 2008; Storz et al., 2000). It is widely used in environmental and engi­neering (Dahlin, 2001; Chambers et al., 2006) and mineral exploration (White et al., 2001; Legault et al., 2008) sur­veys. There have been many recent advances in instru­mentation and data interpretation resulting in more efficient surveys and accurate earth models. In its most basic form, the resistivity meter injects a current into the ground through two metal stakes (electrodes), and mea­sures the resulting voltage difference on the ground sur­face between two other points (Figure 1). The current (I) and voltage (V) values are normally combined into a single quantity, the apparent resistivity, which is given by the following relationship:

Locations

Berlin 52° 31' 9.0156" N, 13° 24' 21.9276" E
8° 0' 14.8032" S, 108° 32' 41.7192" E

LandMapper ERM-02 - versatile and affordable

Landmapper - field EC meter with lab accuracy

Don’t break your back collecting soil samples. Reduce amount of samples sent for laboratory analysis and save money. And still make detail soil map of your fields, which will be more accurate than conventional soil surveys. Impossible? Not at all with LandMapper ERM-02.
This device measures three important electrical properties of soil: electrical resistivity (ER), conductivity (EC), and potential (EP). Utilizing the most accurate four-electrode principle LandMapper measures ER or EC and helps delineate areas with contrasting soil properties within the fields quickly, non-destructively and cost-efficiently.

In a typical setting, a four-electrode probe is placed on the soil surface and an electrical resistivity or conductivity value is read from the digital display. Using the device prior to soil sampling you can significantly reduce the amount of samples required and precisely design a sampling plan based on the site spatial variability.
Bulk soil EC was correlated with salinity, texture, stone content, bulk density, total available nutrients, water holding capacity, and filtration rates. Guided by detailed soil EC map obtained with LandMapper, only minimal amount of soil samples is needed to invert EC map into correlated soil properties. Also, LandMapper can be used to measure EC in soil pastes, suspensions and solutions and quickly estimate total dissolved salts (TDS) in solid and liquid samples.

Locations

Beltsville 39° 2' 5.3952" N, 76° 54' 26.9064" W
34° 57' 16.8984" N, 91° 38' 52.6164" W
56° 17' 1.7628" N, 36° 59' 27.4812" E
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