The water inside a tensiometer has to be part of the soil water body to be able to measure soil water suction. This is provided by the porous ceramic tip at the bottom of the tensiometer. The water containing neck of the tensiometer can be of variable length. The length of the neck is depending of the depth in which we like toe measure water suction.

If the soil water suction is higher than -100 mBar (-10 cBar) this suction is expressing on the tensiometer and it can be measured by a manometer or by an electronic pressure sensor at the top of the tensiometer. Tensiometers can not give results if the soil water contend is higher than field capacitance.

The maximum soil water suction which can be measured by a tensiometer is limited by its pressure sensor or manometer and by the ceramic tip. The electronic pressure sensor provided by Pessl Instruments can measure suction up to -800 mBar. The ceramic tip of our sensors will brake trough at approximately -2000 mBar. The break trough means that the tensiometer will lose all its water because some of the pores of the ceramic tip are wider than the pores holding water at -2000 mBar suction and this wider pores are becoming air filled and the air will enter the tensiometer neck and the water will run out of the tensiometer.



Created by system. Last Modification: Tuesday 28 of April, 2009 12:42:58 GMT by tanja.