Tensiometers - SWT4, SWT4R and SWT5

• Excellent accuracy in wet and irrigated soils
• Easy refill model available

A range of loggable, water-filled, pressure transducer tensiometers to measure soil water potential in many different soil environments.

These precision, water-filled, ceramic cup tensiometers have good accuracy (±0.2kPa) over the range +100 to -160 kPa. The SWT range of tensiometers require refilling and degassing after dry periods and the SWT5 model must be protected from frost.

Tensiometer, refillable, types SWT4 and SWT4R

The SWT4 contains water in the cup only, which gives improved frost resistance. The R version can be filled and emptied without being removed from the ground. Shaft lengths from 40 to 2110 mm are available. The measurement range is +100 to -85 kPa

Tensiometer, miniature, type SWT5

The SWT5 is very compact and creates minimal soil disturbance – it can be used in confined spaces such as plant pots. It has a water filled shaft and cup and is therefore not frost resistant. Shaft lengths from 20 to 200 mm are available; the ceramic cup is only 5mm diameter and 5mm length. The measurement range is +100 to -85 kPa for the standard SWT5 model and +100 to -160kPa for the extended range SWT5x model.

Applications

Applications include monitoring crop water stress, irrigation scheduling and tracking gradients of hydraulic potential when analysing directions and rates of water flow. Their ability to respond to positive hydraulic heads allows them to monitor water table height when submerged (and the overburden, if present).

The SWT range of tensiometers requires a stabilised 10.6V DC, 1.3mA power source. A DL2e Data Logger, with a TVB1 Voltage Regulator can power and log up to 30 tensiometers (or 60 with special cable arrangements). Alternatively, a GP1 Data Logger, fitted with a GP1-PBA-X50 adapter board can log 1 or 2 tensiometers.