The Irrometer operates on the tensiometer principle, which is entirely different from other systems which measure percent of moisture. The Irrometer consists of a sealed water filled tube equipped with a special vacuum gauge and with a porous tip that is installed in the ground at the desired root zone depth. In dry soil, water is drawn out of the instrument, creating a partial vacuum which is registered on the gauge. The drier the soil, the higher the reading. An irrigation reverses this action. The vacuum created by dry soil draws water back into the instrument from the soil, which in turn results in lower gauge reading. Due to this unique principal of operation, no calibrations are necessary under normal operating conditions for different soil types. The Irrometer covers the entire range of soil moisture required for optimum growth. You'll quickly learn the range of Irrometer readings, at which irrigations in your rose garden should stop and start. The Irrometer is easy to use, and scientifically accurate for evaluating your water use, soil moisture content, water penetration, and preventing waste.
Installation is best made by using a 7/8" diameter pointed rod or pipe. For Roses drive the rod to a depth of approximately 12" and remove and insert the Irrometer. This method assures good contact between soil and tip witrh minimum damage to roots and soil structure.