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Tensiometers |
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Model SR Tensiometer
Model TEN Tensiometer
Typical tensiometer station
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The Model SR tensiometer is designed to be the most economical tensiometer commercially available. It is manufactured in France, and is used extensively throughout France and Europe. Its simple construction and Bourdon-tube gauge make it an inexpensive yet accurate and reliable instrument.
The Model Ten tensiometers offer versatility as well as reliability. The dial gauge and ceramic cup are replaceable. The recalibrateable gauge allows the water-column offset and any gauge offset to be zeroed out, providing more accurate soil-tension measurements. Threaded ports allow easy attachment of electronic transducers or vacuum switches.
Features •
direct measurement of moisture conditions • large inner-diameter body tube and water reservoir
Model SR • sealed, weatherproof dial gauge • water trap keeps Bourdon tube filled with water, reducing temperature effects on gauge readings
Model TEN • replaceable ceramic cup • recalibrateable gauge • angled gauge placement for easier reading • two ¼-NPT threaded ports for connection of accessories
Installation and operation Tensiometers are simple to install and operate. A hole is augered to the desired depth of measurement and the tensiometer is inserted, ensuring that the porous ceramic cup is in good contact with the soil.
Two or three tensiometers are often installed in one location, to monitor within and at the bottom of the active root zone. Periodically, a visit is made to the site, and the dial gauge on the tensiometers are read manually.
The data can be recorded and graphed to evaluate moisture conditions and changes in the moisture content. Measurements help determine when an irrigation is necessary in order to maintain optimal moisture conditions.
Datalogging readings with electronic transducers Tensiometer measurements can be automated by attaching an electronic transducer to the tensiometer, and wiring the transducer to a datalogger. An accurate time series of moisture data is collected, for use in monitoring moisture and water use, or for calibrating electronic moisture sensors.
Interpreting readings Tension readings are often used to determine when an irrigation is needed. The grower establishes a critical level of moisture depletion which will be allowed, beyond which vegetative growth or fruit quality are affected. As the soil dries, tensiometer readings increase in response to roots having to pull harder to extract water from the soil. When the readings approach the critical moisture level, the irrigation point, an irrigation is needed.
It is also important to monitor the moisture conditions at the wet end. Over-irrigations can result in standing water and saturated soils, lack of oxygen, poor root and plant respiration, and plant damage. Tensiometer readings can provide information about the infiltration and drainage properties of the soil, and detect periods of saturated conditions.
Experience with moisture measurements, the information they provide, and how this information is used at the field level can lead to improvements and greater efficiency in irrigation system management, more timely and appropriate water and chemical applications, more consistent growing conditions, and improvements in plant health and fruit quality.
Having accurate and timely information about the below-ground moisture conditions allows the grower to fine-tune his irrigation system and maintain optimal conditions for optimal production.
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Earth Systems Solutions Santa Barbara, CA 93111 USA Phone:1+805-967-2726 |
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