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Enabling better global research outcomes in soil, plant & environmental monitoring.

Decagon EC-5 Moisture

A low cost sensor for measuring volumetric water content of soil

The EC-5 is used to measure volumetric moisture content of soils and other material for scientific research and agricultural applications. The EC-5 measures volumetric water content via the dielectric constant of the soil using capacitance technology. The sensor uses a 70 MHz frequency, which minimises salinity and textural effects, making it an ideal sensor in agricultural and standard scientific projects.

The EC-5 has a small area of influence. The sensor is 5cm in length and can measure a small volume of soil, ideal in situations such as glasshouse pots or localised areas of soil moisture (for example, soil for small herbs).

  • High resolution allows daily or hourly tracking of water use
  • Voltage output proportional to water content
  • Low-cost dielectric water content sensor
  • Very low power requirement


Measurements taken Volumetric water content
Range 0-60% VWC
Accuracy VWC: Using Standard calibration: ±5% typical on mineral soils, ±1-2% with soil site specific calibration
Time 10 ms (milliseconds)


Power Requirements 2.5-5V DC @ 10mA
Stable excitation voltage required

Operating Conditions

Operating Temperature 0°C to +50°C


Frequency 70MHz
Output Range 375 mV (dry soil) to 1000 mV (saturated)


Connector Types 3.5 mm “stereo” plug or stripped and tinned lead wires
Cable Length 5m standard
Dimensions Dimensions 8.9 x 1.8 x 0.7 cm


MEASURES volumetric water content, dielectric permittivity volumetric water content, dielectric permittivity volumetric water content, dielectric permittivity, temperature volumetric water content, dielectric permittivity, temperature, electrical conductivity volumetric water content, dielectric permittivity, temperature, electrical conductivity water potential,
VOLUME OF INFLUENCE 0.3 L 1 L 0.3 L 0.3 L 0.3 L N/A
DATA LOGGER COMPATIBILITY Em5b, Em50, Em50R, Em50G, ProCheck, ECH2O Check, Campbell Scientific* Em5b, Em50, Em50R, Em50G, ProCheck, ECH2O Check, Campbell Scientific*

Em50, Em50R, Em50G, ProCheck, Campbell Scientific*, SDI-12 capable

Em50, Em50R, Em50G, ProCheck, SDI-12 capable

Em50, Em50R, Em50G, ProCheck, SDI-12 capable

Em50, Em50R, Em50G, ProCheck, SDI-12 capable

MEASUREMENT RANGE 0 to 100% VWC 0 to 57% VWC

0 to 100% VWC

-40 to 50°C

0 to 100% VWC

-40 to 50°C

0 to 23 dS/m

0 to 100% VWC

-40 to 80°C

0 to 23 dS/m

-10 to -500 kPa (pF 2 – pF 3.71)

-40 to 50°C

BEST IF VWC is all that you need.You’re establishing a large sensor network. You want a large volume of influence.

You have high temperature variability in your soils.

You are monitoring shallow or desert soils where data must be corrected for temperature effects.

You need to monitor soil temperature for biological activities.

You want to use SDI-12.

You are managing salts in your system.You want to use SDI-12.

You are measuring water content of soilless substrates.

You need high accuracy EC.

You need to measure at high temperatures

You want to compare soil moisture at different research sites.

You want to determine water available for plant growth.

You are monitoring deficit irrigation.

You want to measure water potential.

BUT NOT IF You cannot apply a regulated voltage (only applies to non-Decagon data loggers). You are measuring in nursery pots.You are installing in rocky soil. N/A You want to monitor soiless substrates or potting soils. You are doing downhole installations. You want to monitor soils at or near saturation.

Lowest Cost Individual Sensors for Large Sensor Networks

Looking for a basic, no-frills soil moisture sensor? Look no further than the EC-5, a sensor that accurately measures water content in any soil or soilless media with minimal salinity and textural effects.

The EC-5 delivers research-grade accuracy at a price that makes large sensor networks economically practical. You can adequately characterise your site with sensors at multiple depths and locations, even if you’re on a tight budget.

Engineered for Accuracy

The EC-5 determines volumetric water content (VWC) by measuring the dielectric constant of the media using capacitance/frequency domain technology. Its 70 MHz frequency minimises salinity and textural effects, making this sensor accurate in almost any soil or soilless media. Factory calibrations are included for mineral soils, potting soils, rockwool, and perlite.

Easy Installation

Just 5 cm long with a 0.3 L measurement volume, this handy little sensor is easy to install in the field and can also be used in nursery pots. The EC-5´s robust design makes it easy to push directly into undisturbed soil to ensure good accuracy.

Integrate with CSI Data Loggers

The EC-5´s analogue signal means no-hassle integration with systems manufactured by other companies, such as Campbell Scientific.

Reasons to pick the EC-5:

  • If volumetric water content is the only measurement you need.
  • If you are on a tight budget.
  • If you want a basic, all-purpose sensor with excellent accuracy.
  • If you are interested in a small volume of influence (eg. field spatial variability, lab column studies, or greenhouse research).
ECH2O Soil Moisture Sensor References
Bogena, H.R., Huisman, J.A., Oberdörster, C. and Vereecken, H. 2007, ‘Evaluation of a Low Cost Soil Water Content Sensor for Wireless Network Applications’, Journal of Hydrology, vol. 344, pp. 32-42.

Borhan, M.S., Parsons, L.R. and Bandaranayake, W. 2004, Evaluation of a Low Cost Capacitance ECH2O Soil Moisture Sensor for Citrus in a Sandy Soil, 25th International Irrigation Show, Tampa, Florida. 14-16 November 2004 pp. 447-458.

Campbell, C.S., Application Note: Response of ECH2O Soil Moisture Sensor to Temperature Variation, Decagon Devices: 1-6.

Campbell, C.S., Application Note: Response of the ECH2O Soil Moisture Probe to Variation in Soil Water Content, Soil Type, and Solution Electrical Conductivity, Decagon Devices: 1-5.

Christensen, N.B. 2005, Irrigation Management using Soil Moisture Monitors, Western Nutrient Management Conference, Salt Lake City, UT, USA. pp. 46-53.

Czarnomski, N.M., Moore, G.W., Pypker, T.G., Licata, J. and Bond, B.J. 2005, ‘Precision and Accuracy of Three Alternative Instruments for Measuring Soil Water Content in Two Forest Soils of the Pacific Northwest’, Canadian Journal of Forest Research, vol. 35, pp. 1867-1876.

Decagon Inc., Application Note: ECH2O Dielectric Probes vs Time Domain Reflectometers (TDR), Decagon Inc.: 3 pp.

Kizito, F., Campbell, C.G., Cobos, D.R., Teare, B.L., Carter, B. and Hopmans, J.W. 2008, ‘Frequency, Electrical Conductivity and Temperature Analysis of a Low-cost Capacitance Soil Moisture Sensor’, Journal of Hydrology, vol. 352, pp. 367-378.

Laurent, J.P., Olivier, F. and Goure, J.P. 2005, Monitoring Moisture Content in Municipal Solid Waste: Results of a Preliminary Test under Laboratory Conditions, International Workshop on Hydro-Physico-Mechanics of Landfills, Grenoble Univerisity. 21-22 March.

Luedeling, E., Nagieb, M., Wichern, F., Brandt, M., Deurer, M. and Buerkert, A. 2005, ‘Drainage, Salt Leaching and Physico-chemical Properties of Irrigated Man-made Terrace Soils in a Mountain Oasis of Northern Oman’, Geoderma, vol. 125, pp. 273-285.

Mattson, E.D., Baker, K.E., Palmer, C.D., Breckenridge, C.R., Svoboda, J.M. and Smith, R.W. 2006, ‘A Flexible Water Content Probe for Unsaturated Soil Column Experiments’, Vadose Zone Journal, vol. 5, pp. 805-808.

McMichael, B. and Lascano, R.J. 2003, ‘Laboratory Evaluation of a Commercial Dielectric Soil Water Sensor’, Vadose Zone Journal, vol. 3, pp. 650-654.

Sakaki, T., Limsuwat, A., Smits, K.M. and Illangasekare, T.H. 2008, ‘Empirical Two-point α-mixing Model for Calibrating the ECH2O EC-5 Soil Moisture Sensor in Sands’, Water Resources Research, vol. 44, pp.

Smith, P. and Christie, J. 2006, Practical Irrigation Scheduling of Pastures under Centre Pivot Irrigators, Irrigation Australia 2006 Conference, Brisbane.