World's First Fully Integrated TRUE TDR Digital Soil Moisture Sensor. Updated.



A joint venture between Acclima and the USDA, Acclima's patented TDR-315H® Soil Moisture Sensor is the culmination of years of research, testing and product development.

The first fully integrated digitized Time Domain Reflectometer (TDR), providing highly accurate absolute readings of soil moisture under all conditions of temperature and soil chemistry under which crops will grow.

No other soil moisture sensor on the market matches its accuracy and stability. Bar none.

  • No external signal generation/processing electronics equipment needed

  • Costs a fraction of the price of traditional TDRs

  • TDR accuracy

  • Convenient SDI-12 Digital output



  1. Volumetric Water Content (0 to 100% with 0.1% resolution)

  2. Permittivity (1 to 80 with 0.1 unit resolution)

  3. Bulk EC (0 to 5000 μS/cm - resolution depends on reading range)

  4. Pore Water EC (0 to 55000 μS/cm)

  5. Temperature (- 40 to +60 degrees C with 0.1 degree resolution)



Widely recognised as the pinnacle of moisture sensing technology, TRUE TDR sensors have always been limited by a number of factors: low portability, bandwidth limiting coaxial lead cable, and high cost (many thousands of dollars). 

The founder of Acclima Inc, Scott Anderson has changed all that. Leading years of research refining and miniaturising TDR technology, this year releasing this sensor with all required electronics, algorithms and signal processing contained within the sensor's rugged epoxy resin casing with an industry standard SDI-12 interface. 

Highly suited to "insertion style" soil readings making the sensor very user-friendly in the field.

Huge 150ml sample volume - significantly larger than Capacitance probes.


Acclima Reliability

Rugged 316 stainless-steel waveguide. Expected in-service life in excess of 20 years.



Latest TDR-315 News

TDR-315 Research Paper by Dr Robert Schwartz, USDA



  • Large 150 ml soil sample volume

  • SDI-12 Version 1.3 Interface

  • Compatible with SDI-12 Data Loggers including Acclima's DataSnap

  • Derives VWC from ±1% of true permittivity in soils out to 4 dS/m Bulk EC

  • Soil temperature resolution ±0.2 degree C.

  • No calibration. Works in ALL soils

  • No maintenance, simple penetration-style insertion

  • Linear range of 0-100% volume water content

  • Moisture readings remain stable as soil salinity, fertiliser content & temperature change

  • Moisture sense time of <1 second

  • Very low power, battery operable

Data Sheet