Soil Water Potential Sensors
Soil water potential sensors measure soil water potential via two methods: heat dissipation or electrical resistance. The sensors determine the energy status of the water in the soil, which describes the force that holds the water in the soil.
Product Line
229-L Heat Dissipation Matric Potential Sensor
The 229 is a sensor that measures soil water potential from -10 to -2500 kPa. It requires that you connect it to either the CE4 or CE8 current excitation module. A Campbell Scientific data logger controls the current excitation module, measures the sensor, and calculates soil water matric potential.
Features:
- Compatible with most Campbell Scientific data loggers
- Measures a wide range of matric potential
- Measurements not affected by salts in the soil
- Long lasting, with no maintenance required
- Compatible with AM16/32-series multiplexers, allowing measurement of multiple sensors
257-L Soil Matric Potential Block
The 257 - L, is a solid-state, electrical-resistance sensing device with a granular matrix that estimates soil water potential from 0 to -200 kPa (typically wetter or irrigated soils). It connects directly to your data logger.
Features:
- Survives freeze-thaw cycles
- Compatible with most Campbell Scientific data loggers
- Contains blocking capacitors in its cable that minimize galvanic degradation and measurement errors due to ground loops
- Buffers salts in soil
- Rugged, long-lasting sensor
Model GEO-MPS2
This is a dielectric water potential sensor that needs no care or feeding. Instead, it can simply be packed into a hole, plugged into a data logger, and left to log water potential data. Its extended range makes this sensor ideal for measuring the water potential in natural systems or other drier systems where cavitation of tensiometers is a concern. The added temperature measurements can be used to determine approximate soil water potential in partially frozen soils.
Features:
- Accuracy Soil Water Potential: ± 25% of reading from -10 kPa to -100 kPa Soil Temperature: ± 1°C
- Resolution Soil Water Potential: 0.1 kPa Soil Temperature: 0.1°C
- Range Soil Water Potential: -10 to -500 kPa (pF 1.71 to pF 3.71) Soil Temperature: -40°C to 50°C
- Measurement Speed: 150 ms (milliseconds)
- Equilibration time: 10 min to 1 hr depending on soil water potential
- Output: RS232 (TTL) with 3.6 volt levels or SDI-12 communication protocol
- Operating Environment: -40°C to 50°C
- Power: 3.6 - 15 VDC, 0.03 mA quiescent, 10 mA max during 150 ms measurement