Tensiometer Tube

The SOILSPEC Tensiometer System has two essential parts:

The tensiometer tube - an inexpensive sealed tube filled with water. It has a porous ceramic tip at the bottom and a rubber stopper in the top, (see diagram). This tube is installed into the ground where you want to measure the soil moisture.

The gauge - a very accurate electronic vacuum gauge. This is used to measure the vacuum (or suction) at the top of the tubes. There are two models of gauge available for use with the tensiometer tubes. The Standard gauge (Model SST101G) simply reads the vacuum in the tensiometer tube. You then note down the readings and add this to your plots of soil moisture. The Computer gauge (Model SST102G) will store the readings along with the tube ID, time and date. This is then downloaded to your PC using the simple to use MoisturePlot software supplied with the gauge.

HOW THE SOILSPEC SYSTEM WORKS

As the soil dries out, the surface tension of the moisture in the surrounding soil attempts to draw the water out of the tube through the porous ceramic tip. However, because the tube is sealed with a rubber stopper, the water cannot escape. The suction at the ceramic tip then creates a pressure reduction in the air space at the top of the tube. Dry soil around the tip has a high suction. When irrigation or rainfall occurs, and the soil becomes moist, the tension (or suction) at the ceramic tip reduces, decreasing the vacuum at the top of the tube. If we use a vacuum gauge to read the vacuum level at the top of the tube, a high reading indicates that the soil is dry at and around the ceramic tip, and a low vacuum reading shows that the soil is moist. Simple, but very effective!!

What's more, the SOILSPEC System indicates directly how much water is available to your crop.

In general a complete monitoring system will consist of a number of monitoring sites around the area to be irrigated. Each site would have two or three tubes of different lengths. This not only allows the monitoring of soil moisture at a number of depths at each site, but it also shows, from the graphs, the movement of the moisture through the soil during the irrigation cycle.

The SOILSPEC system requires very little maintenance and will provide years of reliable service. The SOILSPEC electronic gauge requires no periodic calibration or zeroing prior to use.

Tensiometers in the field are read and the results recorded regularly. The figures from each Tensiometer tube are then graphed to provide a picture of soil moisture.