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Decagon 5TM VWC + Temp

The 5TM delivers temperature, measured by an onboard thermistor, along with accurate volumetric water content.

The 5TM determines volumetric water content (VWC) by measuring the dielectric constant of the soil (or other media) using capacitance/frequency domain technology.

Signal filtering minimises salinity and textural effects, making the 5TM accurate in most soils and soilless media. Factory calibrations are included for mineral soils, potting soils, rockwool, and perlite.

5TM Soil Moisture Sensor Features
Easy Installation

The 5TM’s small size makes it easy to install–perfect for in field installations. This robust probe can be pushed directly into undisturbed soil to ensure good accuracy. Its compact design makes it useful not only in the field, but also in labs or greenhouses.

Plug and Read

Get straight to the data with an Em50-series data logger. Just install the 5TM, plug it into the Em50, set the clock and measurement intervals, and start logging data. No programming required.

Applications:

  • Greenhouse Management
  • Microbial Ecology
  • Watershed Characterisation
  • Plant Ecology
  • Soil Respiration

Best if you have high temperature variability in your soils.
Best if you are monitoring shallow or desert soils where data must be corrected for temperature effects.
Best if you need to monitor soil temperature for biological activities

 

Volumetric Water Content

The 5TM sensor uses an electromagnetic eld to measure the dielectric permittivity of the surrounding medium. The sensor supplies a 70 MHz oscillating wave to the sensor prongs that charges according to the dielectric of the material. The stored charge is proportional to soil dielectric and soil volumetric water content. The 5TM microprocessor measures the charge and outputs a value of dielectric permittivity from the sensor.
Temperature.
The 5TM uses a surface-mounted thermistor to take temperature readings. The thermistor is underneath the sensor overmold, next to one of the prongs, and it reads the temperature of the prong surface. The 5TM outputs temperature in C unless otherwise stated in DataTrac 3 or ECH2O Utility preferences fi le.
It is important to note that if the black polyurethane overmold of the sensor is in direct sunshine, the temperature measurement may read high. We do not recommend that the sensor be installed with the overmold in the sun.

5TM SOIL SENSOR
ACCURACY Apparent Dielectric Permittivity (Ka): ± 1 Ka from 1 – 40 (soil range); ± 15% from 40 – 80 Soil.
Volumetric Water Content (VWC) Using Topp equation: ± 0.03 m3/m3 (± 3% VWC) typical in mineral soils that have solution electrical conductivity less than 10 dS/m. Using medium specific calibration, ± 0.02 m3/m3 (± 2% VWC) in any porous medium.
TEMPERATURE ± 1°C
VWC 0.0008 m3/m3 (0.08% VWC) from 0 to 50% VWC Temperature: 0.1°C
RANGE VWC: 0 – 100% Temperature: -40 – 50°C
DIMENSIONS 10 cm x 3.2 cm x 0.7cm
CABLE LENGTH 5 m standard, custom cable lengths available upon request
MEASUREMENT TIME 150 ms (milliseconds)
POWER 3.6 – 15 VDC, 0.3 mA quiescent, 10 mA during 150 ms measurement
CONNECTOR TYPES 3.5mm “stereo” plug, or stripped and tinned lead wires (3)
OUTPUT RS232 or SDI-12
DATALOGGER COMPATABILTY Em50 Series

SENSOR COMPARISON TABLE

ANALOGUE SENSORS DIGITAL SENSORS
SENSOR EC-5 10HS 5TM 5TE GS3 MPS-2
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,
temperature
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.

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Related Analysis:

Related Research
Related Case Studies
 

Documents:

5TM Manual
5TM Integrators Guide
Soil Water Content Measurement Methods
5TM Brochure