IRROMETER Tensiometer:

The Tensiometer is the only direct measurement system available, which means that it actually reads the physical forces at work in the soil. Tensiometers act like a dummy root, allowing the soil moisture to interact with the instrument through the ceramic tip. Soil water tension outside of the instrument tries to remove the water from it, which creates a measurable tension inside the column. This tension is read with either a mechanical gauge or a transducer attached to the instrument. While this is the most accurate and proven method available, there is some maintenance required periodically to keep them full of water, and they must be removed from the field during the winter months to avoid freezing.