SMT100 Soil Temperature and Humidity SensorThe SMT100 soil temperature and humidity sensor is a low-cost, high-quality sensor produced by TRUEBNERS in Germany. Its principle is to use a ring oscillator to convert the transmission time of the signal into a measurement frequency, and the generated frequency>100MHz is sufficient for normal operation in cohesive soil. SMT100 combines the advantages of low-cost FDR sensors with the accuracy of TDR sensors. Like TDR, it measures the propagation time of signals to determine the dielectric constant of soil, and like FDR, it converts the dielectric constant into an easily measurable frequency. We offer multiple output modes including SDI-12, RS485, 0-10V, and Modbus to meet the needs of our customers.

Application scope of soil temperature and humidity sensor:
Meteorology, agriculture, soil, greenhouse, measurement of straw moisture, soil erosion, measurement of compost moisture, measurement of snow moisture and temperature, civil engineering and greening, diversified irrigation and other fields

Technical indicators of soil temperature and humidity sensor:
Moisture range: 0-60% VWC (Max: 100% VWC)
Resolution: 0.1% VWC or higher
Accuracy: ± 3% VWC factory calibration @ between 0-50% VWC mineral soil salinity~8ds/m
± 1% VWC @ Soil Specific Calibration

Temperature range: -40~+80 ℃
Resolution: 0.01 ℃
Accuracy: Typical ± 0.2 ℃ @ -20~+50 ℃; Other ± 0.4 ℃

Dielectric constant: 1 (air)~80 (water)
Resolution: 0.01
Response time: 50us
Power supply: 4-24V DC
Current: 40mA
Signal output: Digital: RS485, Modbus, SDI-12
Simulation: 0-10 V
Cable length: 10m
Size: 18.2 cm x 3 cm x 1.2 cm

Soil temperature and humidity sensor


Characteristics of the three types of soil moisture sensors used in the SOMOMOUNT network. All values in the table are provided by the manufacturers (Delta-T Devices, 2008; IMKO, 2015; Truebner, 2016).


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