TDR-300 soil moisture meter

Portable TDR Moisture Meter

  • Portable, easy to use, soil moisture meter
  • Measure volumetric water content or relative water content
  • In-built data logger, Bluetooth downloads to mobile maps, and email data from the field
  • Optional GPS capabilities
When precision irrigation decisions count, the TDR-300 Soil Moisture Meter Series offers growers a tool to eliminate the guesswork. Based on proven time-domain measurement technology, these portable units accurately measure soil moisture across the full range of soil moisture conditions. Select from the 3.8, 7.5, 12 or 20-cm probe rods to suit your desired depth measurement. Install PVC access tubes and take readings deeper in the soil profile for permanent crops like apple, grapes, and nut crops.
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application notes


Time Domain Reflectometry

The TDR 300 has two volumetric water content modes; one for standard soils and one for higher clay soils. In volumetric water content (VWC) mode, the meter converts a measured electrical signal into percent soil moisture content using an equation valid over a wide range of mineral soils. In irrigation mode, the meter displays a relative water content (RWC) on a scale of 0 to 100 corresponding to a user-defined upper and lower soil moisture reference level. Water deficit, the amount of water needed to bring the soil moisture content up to the upper reference level, is also calculated and displayed. The reference levels are easily programmed into the meter with the accompanying software. Create up to 2 management sites based on your soil types and crop needs. Use the raw reading mode (measurement period in microseconds) to do soil-specific calibrations.

  • FieldScout Soil Moisture MeterInstantaneous readings of root zone soil moisture
  • Introducing the new FieldScout Bluetooth Device, connects to the FieldScout Mobile App, instantly see your data on your smart phone or tablet (more information below)
  • Connects to any GPS receiver with serial output**
  • Equipped with internal data logger and RS-232 port
  • Records 3,250 measurements (1,350 with added GPS/DGPS option)
  • Configure and download meter with FieldScout software (included)*
  • Compatible with SpecMaps online web-mapping application
  • TDR 300 meter includes soft-sided carrying case (Item 6430CASE)
  • Rods sold separately
  • Firmware chip not required for new purchases – only if your TDR is pre-January 2012.  Firmware version 6.5 or higher required for FieldScout Bluetooth Device connection


feature specification
Measurement Principle Time Domain Reflectometry (TDR)
Measurement Units Volumetric water content (% VWC) | relative water content (% RWC) | raw values (microseconds)
Resolution 0.1% volumetric water content
Accuracy ±3.0% VWC with manufacturer's calibration | ±0.0% VWC with custom calibration
Range 0% to 100% with custom calibration
Power Supply 4 x AAA alkaline batteries; approximately 12-month battery life
Data Logger Memory 3,250 measurements without GPS | 1,350 with GPS



Bluetooth enabled

Soil Moisture MeterNew – FieldScout Bluetooth Device connects to the FieldScout Mobile App, instantly see your data on your smart phone or tablet.  App works on iOS and Android devices with Bluetooth Smart connection.

Your existing TDR 300 can now be equipped with our FieldScout Bluetooth Device.  The device plugs into the data port in the bottom of the TDR’s console, making installation simple. Included velcro strips allow you to mount it in a  location on the TDR bracket.

Firmware version 6.5 or higher required for FieldScout Bluetooth Device connection (order Item #CHIP-TDR3 above for newest firmware version)


FieldScout mobile app

Soil Moisture MeterUse the FieldScout Mobile app to instantly collect and display data on your smart phone or tablet, from your Bluetooth enabled FieldScout TDR 300 Soil Moisture Meter or FieldScout TruFirm Firmness Meter. The app allows you to see and email information on a grid of zones (3 wide by 3 deep). FieldScout Bluetooth Device connects to the FieldScout Mobile App.

  • Collects data from FieldScout TDR 300 Soil Moisture Meter (Bluetooth device required) and FieldScout TruFirm Turf Firmness Meter using Bluetooth Smart connection
  • Uses your smart phone for time-stamping and geo-referencing the data
  • On-the-go means of collecting data from FieldScout meters
  • Color coded to represent a scale of turf firmness or moisture
  • Eliminates the need for a computer, cable, and GPS accessory
  • Visualize readings in real time
  • E-mail relevant information
  • FieldScout TDR 300 requires new FieldScout Bluetooth Device (Item 6453BT above)
  • Compatible with iOS and Android smart phones and tablets, device requires Bluetooth Smart Ready
  • Free download from App Store or Google Play (see links below), Pro version requires a SpecConnect subscription



TDR-300 Soil Moisture Meter Manual


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