Decagon's ECH2O probes have been used to measure soil moisture worldwide for 5 years. They use new technology and durable materials to enable you to perform accurate long-term moisture content monitoring. Because of this, you can measure at different depths over a wide geographic area, and at a relatively low cost. The ECH2O probes measure the dielectric constant of the soil in order to find its volumetric water content. They do this by finding the rate of change of voltage applied to the sensor once it is buried in the soil. There are other probes that measure water content this way, but the ECH2O probe is the only one of its kind to have a comparatively low sensitivity to saline and temperature effects in the soil. Furthermore, it has a very low power requirement, which makes long-term monitoring more cost-effective. And its extremely high resolution makes it possible to accurately monitor water use daily or even hourly. Also, the new ECH2O TE probe allows you to measure temperature and electrical conductivity (EC) together with the water content, giving you more useful information about the conditions of your soil. Following is a table of the ECH2O probe types and their general specifications. They all share the following specifications:
Cable Length: 5m
Operating Environment: -40 to 50 °C, 0 - 100% RH
Measurement Time: 10ms
Resolution: 0.002m3/m3 typical with Em50 and Em5b loggers; other loggers may vary.
Specifications
Probe Type
Sensor Length
Measurement
Accuracy
Range
Electrical Interface
Supply Voltage
Frequency
Output
EC-5
5cm
Volumetric Water Content
± 3% typical, 1-2% with soil-specific calibration
0 - 100% VWC
3.5 mm plug or tinned 3-wire lead
2.5-5V DC @ 10mA
70 MHz
Voltage, correlated linearly (soil) or polynomially (growing media) with VWC
EA-10
10cm
Volumetric Water Content
±4% typical on low EC and medium-textured mineral soils, 1-2% with soil-specific calibration
0-40% VWC
2-wire analog, 4-20mA
line-powered 7-32 VDC, overvoltage and reverse-polarity protected
N/A
4-20mA Current, correlated linearly w/soil VWC
ECHO TM
5cm
Volumetric Water Content, Temperature
MINERAL SOIL : ±4% VWC,1-2% VWC with soil-specific calibration. ROCKWOOL ±3% VWC POTTING SOIL ±3% VWC
0-100% VWC
3.5 mm plug or tinned 3-wire lead
3-15VDC, 0.3 mA quiescent, 10 mA for 9 ms measurement
70 MHz
Voltage, correlated linearly w/soil VWC
5TE
14.5cm
Volumetric Water Content, Temperature, Conductivity
±1 Dielectric
1-50 Dielectric Permittivity
3.5 mm plug or tinned 3-wire lead
3-16 VDC
Digital 12-bit
10HS
14.5cm
Volumetric Water Content
MINERAL SOIL : ±2% VWC soil specific calibration ROCKWOOL ±3% VWC POTTING SOIL ±3% VWC
0-100% VWC
3.5 mm plug or tinned 3-wire lead
3 to 15 VDC 12 mA @3V, 15 mA @ 15V
Voltage, correlated linearly with VWC,independant of excitation voltage
