SMTE Soil Moisture, Temperature, EC sensor
for RTH

SMTE Soil Moisture, Temperature, EC sensor

Overview

SMTE sensor is a modified version of the ECH2O-TE Probe (Decagon Devices Inc., USA), which was adapted for operation with the RTH Meter, a smart environmental measurement unit, which is a part of PM-11 Phytomonitor and PTM-48A Photosynthesis Monitor.

The SMTE is designed to measure the volumetric water content (VWC), electrical conductivity (EC), and temperature of soil and growing media. Using an oscillator running at 70 MHz, it measures the dielectric permittivity of soil to determine the water content. A thermistor in thermal contact with the probe prongs provides an average prong temperature, while the gold traces on the surface of the sensor form a four-probe electrical array to measure electrical conductivity.

Specifications

Dimensions, mm100 W × 32 H × 7 D
Prong Length52 mm
Prong Length70 MHz
ConnectorIP67 BINDER plug
CompatibilityRTH-11/RTH-48 Meter
Factory calibrationMineral soil, Rockwool, and potting soil
Volumetric water content (VWC)
Measurement range0 to 100% VWC
Resolution
Mineral soil0.1% VWC
Rockwool, Perlite, Potting soil0.25% VWC
Accuracy
Mineral soil (up to 8 dS/m)1±3% VWC
Rockwool (0.2 to 8 dS/m)1±3% VWC
Potting soil (3 to 14 dS/m)1±3% VWC
Temperature
Measurement range−40 ℃ to +50 ℃
Resolution0.1 ℃
Accuracy±1 ℃
Electrical conductivity (Bulk)
Measurement range0 to 15 dS/m
Resolution0.01 dS/m
Accuracy±10% from 0 to 7 dS/m2
Output cable length5  m
  1. Electrical conductivities were measured by saturation extract (solution EC)
  2. Note that the 7 dS/m upper limit for the 10% accuracy represents a “bulk EC” not solution EC. Even a saline soil with very high solution EC (>20 dS/m) may not have a bulk EC higher than 7 dS/m.

See also: