How to troubleshoot Soil tensiometers?

a) Constant zero readings or reading fluctuating in low suction range.

1. Refill with water and use a hand pump or syringe to remove air and watch for steady
2. Stream of large bubbles (Champagne bubbles) are normal when servicing.
3. If large bubbles rise an continue a leak is indicated and the source should be determined.
4. If the bubbles rise from the bottom remove tensiometer and replace the
5. If bubbles enter from the side, then tube’s body may have cracked and should be fixed.
6. If the bubbles rise from the gauge the leak way be in gauge or the thread connections. A leaky gauge requires replacements but thread connection can be resealed.
7. If no large bubbles rise, yet reading remains zero the reservoir cup may be cracked or the seal may be detective inspect the O-ring.

b) Vacuum gauge damage or stick in one position or may not respond smoothly with changes in soil water.

1. Check a suspected gauge against known to be in good working condition
2. When the cap removed the tensiometer vertical a gauge should always read zero.
3. A service hand pump version with a gauge of its own, this is used to pull a vacuum and compare the two gauges to fully check calibration. Create suction 2 to 3 times as you correlated the reading of both gauges. if the tensiometer gauge does read the same reading as the vacuum pump. The tensiometer gauge is fault and should be replaced..

c) Unexpected readings. .

1. If tensiometer is serviced, no leaks the gauge check okay. The reading is like okay/ correct.
2. The actual condition are perhaps different than expected, or its possible that site is not representative due to combination of irrigation issues, hardpan, installation problem and other soil variables consider re-installing the tensiometer in a nearby similar location.

d) Reading offset.

1. When cap is installed longer tensiometer will never zero even when saturated as the weight of water column creates some tension.
2. And about 1Cbar for 10cm e.g. tensiometers of 60cm, 90cm and 120cm will read 3cbar, 6cbar and 9cbar respectively.