Moisture Sensor

A TDR (Time Domain Reflectometry) Soil Moisture Sensor is an advanced instrument used to measure the volumetric water content (VWC) of soils by sending a short electromagnetic pulse along waveguides (rods) embedded in the soil, and measuring the travel time or reflection of that pulse. The dielectric permittivity of soil changes significantly with water content, so this method enables accurate, non‑destructive measurement of soil moisture under a wide range of conditions.

These sensors are ideal for agriculture, irrigation management, environmental monitoring, and research applications where precise soil water data is required. They offer high accuracy, fast response, and stability across different soil types and salinity levels.

The TDR-310H is one of Acclima’s H-series sensors, which are very low power and suited perfectly for power-conscious applications. Being part of the Soil Smart Series means that it’s advanced waveform analysis works with all mineral soil types. It is a complete integrated time domain reflectometer that combines ultra-fast waveform generating and digitizing functions with a precision 5 pico-second resolution time base and highly sophisticated waveform digitizing and analyzing firmware that provides true time domain analysis of soil-propagated waveforms.

Its form factor is designed for easy vertical installation in an augered hole using a 34 mm flat-bottomed auger. It mates with a 1” schedule 40 PVC pipe that acts as a handle in its installation to any desired depth. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier.

Key Features

• Ultra-low power consumption and fast response time
• Housing designed for easy bore hole installation at any depth
• Soil Smart analysis works with all mineral soil types
• Incident Wave Amplitude: 400mV
• 20% to 80% Incident Wave Rise Time: 150 ps
• Waveform Digitizing Resolution: 5 ps
• SDI-12 Interface
• 3-element 10cm stainless steel waveguide
• 5m or 10m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 80
• Medium Bulk Electrical Conductivity: 0 to 2000 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

A fully integrated digital TDR soil water content sensor (a.k.a., soil moisture sensor, probe, or meter) that has demonstrated superb accuracy consistently with excellent repeatability.

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The TDR-310N is a replacement to the former Acclima TDR-310L. It has a high voltage waveform output, which makes it effective in taking measurements when the soil electrical conductivity is high. It also consumes more power than the TDR-310H. It is a complete integrated time domain reflectometer that combines ultra-fast waveform generating and digitizing functions with a precision 5 pico-second resolution time base and highly sophisticated waveform digitizing and analyzing firmware that provides true time domain analysis of soil-propagated waveforms. 

Its form factor is designed for easy vertical installation in an augured hole using a 34 mm flat-bottomed auger. It mates with a 1” schedule 40 PVC pipe that acts as a handle in its installation to any desired depth. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier. 

Key Features

• SDI-12 Interface
• 3-element 10 cm stainless steel waveguide
• 5 m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing
• 20% to 80% Incident Wave Rise Time: 300 ps
• Waveform Digitizing Resolution: 5 ps
• Incident Wave Amplitude: 2.3 V

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 100
• Medium Bulk Electrical Conductivity: 0 to 3000 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

A TDR (Time Domain Reflectometry) Soil Moisture Sensor is an advanced instrument used to measure the volumetric water content (VWC) of soils by sending a short electromagnetic pulse along waveguides (rods) embedded in the soil, and measuring the travel time or reflection of that pulse. The dielectric permittivity of soil changes significantly with water content, so this method enables accurate, non‑destructive measurement of soil moisture under a wide range of conditions.

These sensors are ideal for agriculture, irrigation management, environmental monitoring, and research applications where precise soil water data is required. They offer high accuracy, fast response, and stability across different soil types and salinity levels.

A fully integrated digital TDR soil water content sensor, the 315H consumes a fraction of the energy than that of its soil moisture sensor siblings in the N series, but still maintains a 150 pico-second rise time for superb accuracy. Not intended for soils with high clay content or bulk EC above 1800 µS/cm.

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The TDR315H is a true Time Domain Reflectometer soil moisture sensor designed to provide highly accurate Volumetric Water Content Measurements in soils and other porous media. It incorporates the same basic TDR components found in console-based TDR instruments costing 20 times more – housed inside the small enclosure that also supports the 15 cm waveguide. 

The patented TDR function is coupled directly to the waveguide, thus eliminating the coax cable associated with conventional TDR devices. The absence of the coax cable provides the TDR315H with higher bandwidth waveform data thus improving its resolution and sensitivity over expensive conventional TDRs.

The TDR-315H is the replacement to the former Acclima TDR-315 and TDR-315L soil moisture sensors. It is fully compatible with those sensors but incorporates several improvements. It is a complete integrated time domain reflectometer that combines ultra-fast waveform generating and digitizing functions with a precision 5 pico-second resolution time base and highly sophisticated waveform digitizing and analyzing firmware that provides true time domain analysis of soil-propagated waveforms. Its form factor is designed for shallower horizontal installations where it is forced into the sidewall of a trench that has been dug to the desired measurement depth. 

Its main improvements over the 315L soil moisture probe are its faster rise time, its shaped incident wave, its lower power consumption and its very fast response time. Its rise time is as fast as the TDR-315 but its power consumption is much lower than the TDR-315 and its price is also lower. 

Key Features

• True Waveform Digitizing TDR: 5ps Resolution Measures Water Content up to 1.00 m3/m3 
• Reads Soil Bulk EC: 0 to 2000 µS/cm
• VWC Readings not affected by Bulk EC (under 1.8 dS/m for this low power model) 
• VWC Readings not affected by Compaction 
• Soil Specific Calibration not required 
• Accurate Soil Temp Measurements: <±0.25°C
• Supports Time Domain Waveform Download
• Ultra-Fast Incident Wave Rise Time: 150ps 
• Fast Measurement Response: typ. <0.25 sec
• Supports Long Battery Life: .09 J per Reading 
• Low Sleep Current: < 10 µA 
• SDI-12 Interface

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 85
• Medium Bulk Electrical Conductivity: 0 to 2000 µS/cm (Ɵ, ɛ repeatability degrades above 2000 µS/cm BEC)
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

Applications

• In-Situ Soil Water Monitoring for
  Agriculture
• High Credibility Data for CloudBased Analysis
• Gold Standard VWC Reference
• Replacement for Neutron Probes
• Portable Measurements using
  Acclima Reader
• Laboratory and Field Research
  Instrumentation

The Acclima True TDR Soil Moisture Sensor Kit delivers industry‑leading precision and reliability in measuring volumetric water content (VWC) in soils and porous media — using fully integrated Time Domain Reflectometry (TDR) technology. Designed for both field and research applications, this sensor kit offers ultra‑fast waveform generation and digitization, minimal influence from soil electrical conductivity or compaction, and seamless data integration via SDI‑12 protocol. With rugged housing and a “plug‑and‑read” design, it’s ideal for environmental monitoring, agriculture, precision irrigation, geotechnical investigations and long‑term installations.

A fully integrated digital TDR soil water content sensor (a.k.a., soil moisture sensor, probe, or meter) that has demonstrated superb accuracy consistently with excellent repeatability between six different soils including potter’s clay.  It is the first release of Acclima’s Soil Smart moisture sensors.  Allows for waveform capture.

Explore Options

The TDR-315N is a replacement to the former Acclima TDR-315L. It has a high voltage waveform output, which makes it effective in taking measurements when the soil electrical conductivity is high. It also consumes more power than the TDR-315H. It is a complete integrated time domain reflectometer that combines ultra-fast waveform generating and digitizing functions with a precision 5 pico-second resolution time base and highly sophisticated waveform digitizing and analyzing firmware that provides true time domain analysis of soil-propagated waveforms. Its form factor is designed for shallower horizontal installations where it is forced into the sidewall of a trench that has been dug to the desired measurement depth. 

A probe guide is provided to ensure that the waveguide rods are parallel when pushing them into the soil. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier.

Key Features

• Designed for easy use in shallower horizontal applications
• Highest accuracy Acclima sensor configuration
• Soil Smart analysis works with all mineral soil types
• SDI-12 Interface
• 3-element 15 cm stainless steel waveguide
• 5 m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing
• 20% to 80% Incident Wave Rise Time: 300 ps
• Waveform Digitizing Resolution: 5 ps
• Incident Wave Amplitude: 2.3 V

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 85
• Medium Bulk Electrical Conductivity: 0 to 3000 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

This sensor uses the advanced Time Domain Transmission (TDT) technology to measure volumetric water content (VWC) of soil with high accuracy across different soil types and conditions. The digital version (SDI‑12 compatible) provides robust performance even under varying soil conductivity, temperature, and salinity.
It is suitable for precision irrigation management, soil moisture monitoring in agriculture, hydrology, environmental research and long‑term installations.

The TEROS 10 soil water content sensor is a ruggedized version of our basic, no-frills soil moisture sensor. Its 70-MHz frequency minimizes salinity and textural effects, making it accurate in most soil or soilless media. With a tough, epoxy body, the TEROS 10 is designed to withstand some of the harshest field conditions, which means problem-free measurements over the longevity of your research. We’re so confident about the long life of our TEROS sensor line, we’ve increased our standard warranty from one to three years.

The Watermark 200SS from Watermark/Irrometer Company, Inc. is a robust, permanent soil moisture sensor designed to measure soil water tension (matric potential) by using a resistive granular matrix sensing element. When installed in the field, the sensor exchanges water with surrounding soil until equilibrium is reached; as the soil dries, resistance increases, as it wets, resistance decreases.

It offers stable calibration, minimal maintenance, and durability (including resistance to freezing and soil salinity) — making it ideal for long‑term monitoring of soil moisture status in agriculture, irrigation scheduling, environmental monitoring and more.With an easy-to-read LCD display, durable construction, and simple one-button operation, the Watermark Soil Moisture Meter is suitable for field use under various environmental conditions. The device can record multiple sensor readings, store data for later download, and is compatible with standard Watermark 200SS, 200SS-1, and similar sensors.