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Tensiometers – General Information

The growing demand for food supply, on one hand, and depletion of usable water sources, on the other hand, emphasize the importance of efficient and water saving technologies in agriculture. The Tensiometer is the best tool for advanced, reliable monitoring in the field. The Mechanical tensiometer is a simple, yet, cost-effective among our products.

What is a Tensiometer? 

A Tensiometer is a simple, but efficient, device for monitoring soil moisture. 

The Tensiometer reads soil water tension in the soil, which reflects the adhesion power of water to soil particles. The drier the soil, the higher is the measured tension and the plant needs more energy to uptake water.

 The obtained data helps the farmer to decide when and how much to irrigate.

 

The Device's Structure: 

Ami Tens' Tensiometer consists of a plastic tube with a transparent part at the top, to which a porous ceramic tip is attached to the bottom and a vacuum gauge or an electronic transducer is attached at the top. The gauge or the transmitter are used for data display and/or storage.

Operation Principles: 

The ceramic tip is inserted into the active roots zone and should be in a complete touch with the surrounding soil. The tube is filled with water and the water infiltrates through the porous cap to create a link with the soil water. 

The tube is hermetically closed to prevent air penetration.

As the plant evaporates water to the atmosphere it creates a suction power in the roots zone, which increases the adhesion power of water to soil particles, a power we call Water Tension. The water tension is read by a vacuum sensor as negative pressure.

When the soil is wet the tension is low and when it dries the tension is rising.

The higher the tension, the bigger is the energy needed for water uptake.

 Current monitoring helps the user in optimizing the water use. 

It is commonly used to decide when us the irrigation start time by a pre-defined set point. If a second, deeper, device, is used it can help the user tune-up the optimal water quantity. 

Allocation of tensiometers: 

There are no absolute instructions for Tensiometers' allocation but some basic principles are important to remember: 

The location of the tensiometer installation should best represent most of the monitored field. In most cases we will prefer a few testing points in a field, according to professional considerations, and also we prefer to test 2-3 depths in a point, to follow up water changes in different layers and adjust water quantities accordingly.

Data Interpretation:

water tension in each soil type behaves different. One should follow up and learn the behavior of water in his field and find the right set-point for irrigation. Consult your agronomist about this subject.

Gauge Categories:

We define the tensiometers in 2 basic categories: Mechanical Tensiometers, and Analog (electronic) Tensiometers, See specifications in the relevant pages.

Ceramic Tips options:

Our standard ceramic tips are 6 cm. long and they are inserted in a plastic thread and can be easily replaced if it is broken or damaged, We can offer tensiometers with a built-in Ceramic tip, without a thread, for special requests.

Pipe's configurations:

A. Standard strait pipe with a thread on top for a gauge installed on top. For water refill the user should unscrew the gauge.

B. T shape pipe. The gauge is installed to the side outlet and a plastic cap is installed on the top and can be unscrewed for water refill.

C. Angle Type (the pipe is bent to 90Degrees). This model is inserted from the side, It is suitable for crop beds or pot plants or very shallow soil etc.

 

Pipe Lengths:

Our standard lengths are 20/30/40/60/90 cm. for measuring soil moisture in different soil layers. Other lengths can be supplied by special requests.