CS650
CS650
OrderableConfigurable30 cm Soil Moisture and Temperature Sensor
Single-point measurements with a larger sampling volume.
Pricing
Configuration
Sign in for option pricing- w/3m (10ft) per Cable -PF w/Ferrules on WiresCS650-3m
- w/5m (17ft) per Cable -PF w/Ferrules on WiresCS650-5m
- w/10m (33ft) per Cable -PF w/Ferrules on WiresCS650-10m
- w/15m (50ft) per Cable -PF w/Ferrules on WiresCS650-15m
Select a configuration to add to your quote
- Model:
- CS650
- Item Number:
- 45369
- Warranty:
- 1 year
- Lead time:
- 14 days
Overview
The CS650 is a multiparameter smart sensor that uses innovative techniques to monitor soil volumetric water content, bulk electrical conductivity, and temperature. It outputs an SDI-12 signal that many of our data loggers can measure.
Note: The cable termination options for this sensor are not suitable for use with an ET107 station. For this type of station, use the CS650-LC sensor instead, which has a suitable cable connector.
Key Advantages
More accurate in soils with high bulk electrical conductivity
Technical Description
The CS650 consists of two 30-cm-long stainless steel rods connected to a printed circuit board. The circuit board is encapsulated in epoxy and a shielded cable is attached to the circuit board for data logger connection.
The CS650 measures propagation time, signal attenuation, and temperature. Dielectric permittivity, volumetric water content, and bulk electrical conductivity are then derived from these raw values.
Measured signal attenuation is used to correct for the loss effect on reflection detection and thus propagation time measurement. This loss-effect correction allows accurate water content measurements in soils with bulk EC ≤3 dS m-1 without performing a soil specific calibration.
Soil bulk electrical conductivity is also calculated from the attenuation measurement. A thermistor in thermal contact with a probe rod near the epoxy surface measures temperature. Horizontal installation of the sensor provides accurate soil temperature measurement at the same depth as the water content. Temperature measurement in other orientations will be that of the region near the rod entrance into the epoxy body.
Benefits
- More accurate water content measurements in soils with bulk EC up to 3 dS m<sup>-1</sup> without performing a soil-specific calibration
- Larger sample volume reduces error
- Measurement corrected for effects of soil texture and electrical conductivity
- Estimates soil-water content for a wide range of mineral soils
- Versatile sensor—measures dielectric permittivity, bulk electrical conductivity (EC), and soil temperature
Specifications
- Measurements Made
- Soil electrical conductivity (EC), relative dielectric permittivity, volumetric water content (VWC), soil temperature
- Required Equipment
- Measurement system
- Soil Suitability
- Long rods with large sensing volume (> 6 L) are suitable for soils with low to moderate electrical conductivity.
- Rods
- Not replaceable
- Sensors
- Not interchangeable
- Sensing Volume
- 7800 cm3
(~7.5 cm radius around each probe rod and 4.5 cm beyond the end of the rods)
- Electromagnetic
- CE compliant
Meets EN61326 requirements for protection against electrostatic discharge and surge. - Operating Temperature Range
- -50° to +70°C
- Sensor Output
- SDI-12; serial RS-232
- Warm-up Time
- 3 s
- Measurement Time
- 3 ms to measure; 600 ms to complete SDI-12 command
- Power Supply Requirements
- 6 to 18 Vdc
(Must be able to supply 45 mA @ 12 Vdc.)
- Maximum Cable Length
- 610 m
(2000 ft) combined length for up to 25 sensors connected to the same data logger control port
- Rod Spacing
- 32 mm
(1.3 in.)
- Ingress Protection Rating
- IP68
- Rod Diameter
- 3.2 mm
(0.13 in.)
- Rod Length
- 300 mm
(11.8 in.)
- Probe Head Dimensions
- 85 x 63 x 18 mm
(3.3 x 2.5 x 0.7 in.)
- Cable Weight
- 35 g per m
(0.38 oz per ft)
- Probe Weight
- 280 g
(9.9 oz) without cable
Current Drain
- Active (3 ms)
- 45 mA typical
(@ 12 Vdc)
- Active (3 ms)
- 80 mA
(@ 6 Vdc)
- Active (3 ms)
- 35 mA
(@ 18 Vdc)
- Quiescent
- 135 µA typical
(@ 12 Vdc)
Electrical Conductivity
- Range for Solution EC
- 0 to 3 dS/m
- Range for Bulk EC
- 0 to 3 dS/m
- Accuracy
- ±(5% of reading + 0.05 dS/m)
- Precision
- 0.5% of BEC
Relative Dielectric Permittivity
- Range
- 1 to 81
- Accuracy
- ±(2% of reading + 0.6)
from 1 to 40 for solution EC ≤ 3 dS/m
- Accuracy
- ±1.4
(from 40 to 81 for solution EC ≤1 dS/m)
- Precision
- < 0.02
Volumetric Water Content
- Range
- 0 to 100%
(with M4 command)
- Water Content Accuracy
- ±1%
(with soil-specific calibration)
- Water Content Accuracy
- ±3%
(typical with factory VWC model) where solution EC < 3 dS/m
- Precision
- < 0.05%
Soil Temperature
- Range
- -50° to +70°C
- Resolution
- 0.001°C
- Accuracy
- ±0.1°C
(for typical soil temperatures [0 to 40°C] when probe body is buried in soil)
- Accuracy
- ±0.5°C
(for full temperature range)
- Precision
- ±0.02°C
Accessories
(6)CS650G
Rod Insertion Guide Tool
OrderableA200
Sensor to PC Interface
Orderable33815
SDI-12 Terminal Bus Kit
Orderable39121
DIN Rail Terminal Kit with 2 Terminals and 5 Wires
Orderable39642
SDI-12 DIN Rail Terminal Bus Kit without Mounting Bracket
OrderableA151
Single Sensor Terminal Case, Vented with Desiccant
Orderable
Related Resources
Case Studies
Documents
- Technical Paper
SDI-12 Sensor Troubleshooting
November 2023
View Document - Manual
SDI-12 Terminal Bus Kit Getting Started Guide (online)
May 2026
View Document - Brochure
CS650 and CS655 Soil Water Content Reflectometer
September 2011
View Document - Manual
SDI-12 Terminal Bus Kit Getting Started Guide
May 2026
View Document - View all documents
Videos and Tutorials

Measuring Water in the Soil: A Webinar
January 21, 2021 (32:06)
Common theories for making measurements of soil water content
Watch
Webinaire sur l’humidité du sol
February 9, 2021 (18:24)
Soil Moisture Content measurement webinar - French version
Watch
Seminario web Humedad de Suelo
February 9, 2021 (20:51)
Soil Moisture Content measurement webinar - Spanish
Watch
SDI-12 Sensors | Watch or Sniffer Mode
November 27, 2013 (3:20)
Watching communication between an SDI-12 sensor and a datalogger
Watch- View all videos and tutorials

