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We have been helping growers and researchers measure soil moisture
since 1951, and offer two proven, effective, and well researched
methods for measuring soil moisture.
The original "IRROMETER" instrument was the first commercially viable tensiometer available, and is still the standard by which other methods are tested. Our IRROMETER instruments provide a direct measurement of soil water tension, which is the tension all root systems must overcome to extract water from the surrounding soil. Simple, reliable, and accurate, the IRROMETER is still the choice of many successful growers and consultants. Our next option for soil moisture measurement is the WATERMARK sensor. This Granular Matrix Sensor (GMS) offers low cost, accurate readings, and easy integration with electronic reading equipment. First introduced in 1979, the WATERMARK sensor has grown in popularity and gained acceptance worldwide for reliability and accuracy in measuring soil moisture. For over two decades, the WATERMARK sensor has been utilized in numerous research studies around the world. Select a link below for more information or scroll down the page: IRROMETER Tensiometers WATERMARK Soil Moisture Sensors Resources: IRROMETER Reference Manual Agriculture Design Guide IRROMETER Catalog Irrigation Monitoring Using Soil Water Tension (OSU) IRROMETER Soil Moisture Basics For more IRROMETER and WATERMARK sensor document downloads, click here |
Read about IRROMETER technology at work helping Afghan farmers |
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The IRROMETER tensiometer is the standard in accurate soil moisture measurement,
offering growers an inexpensive and reliable means of measuring soil
moisture for irrigation scheduling. An IRROMETER will measure
the actual soil water tension, which indicates the effort required by
root systems to extract water from the soil. Because the
IRROMETER is a true measurement of soil water potential, the instrument
is not affected by salinity and does not require site calibration.
The IRROMETER is available in several models, with standard lengths of 6", 12", 18", 24", 36", or 48" dependent on the rooting depth of the specific crop. Longer lengths are available by request. The Model "R" is the standard one-piece IRROMETER for general use with row, tree, and field crops. Includes reservoir, air free gauge chamber, and hermetically sealed IRROMETER vacuum gauge with dual scale of Centibars and kilopascals (0- 100 CB range). ModelR Brochure (.pdf) The Model "SR" has a threaded replaceable tip as well as all the features of the Model R above. Model SR Brochure (.pdf) The Model "RA"is the Model R with direct switching capabilities. Adjustable Moisture level selector switch may be set at any desired moisture level. The switch will be closed past the setting to actuate the solenoid, time clock, or warning light. Switch available for AC or DC power, please specify when ordering. Model RA Brochure (.pdf) The Model "LT" or Low Tension IRROMETER incorporates a replaceable Quick-Flo tip, and a sealed vacuum gauge which has a full scale of 0-40 cbar. Designed for situations where tensions above 30 cbar are rarely expected. Ideal for very coarse solids, or container-media (non-soil), which can be relatively dry at 10-15 cbar or where rapidly changing soil water content needs to be observed. Model LT Brochure (.pdf) The Model "MLT", or Miniature LT, is considerably smaller in size than a regular IRROMETER. It is specifically designed for the smaller containers used in the greenhouse market. Model MLT Brochure (.pdf) The Model TG is for turf areas where underground installation requiring horizontal placement is desirable. Automation/Output Options: Click here for information about automated or electronic output options for IRROMETER tensiometers. |
Field installation of two Model R IRROMETERs 
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In use since 1978, the patented WATERMARK sensor is a solid state electrical resistance sensing
device that is used to measure soil water tension. As the tension changes with
water content the resistance changes as well. That resistance can be measured using
the WATERMARK Sensor. The sensor consists of a pair of highly corrosion resistant electrodes that are imbedded within a granular matrix. A current is applied to the WATERMARK to obtain a resistance value. The WATERMARK Meter or WATERMARK Monitor correlates the resistance to centibars (kilopascals) of soil water tension. The WATERMARK is designed to be a permanent sensor, placed in the soil to be monitored and “read” as often as necessary with a portable or stationary device. Internally installed gypsum provides some buffering for the effect of salinity levels normally found in irrigated agricultural crops and landscapes. WATERMARK Features 200SS-V Voltage Output Version The WATERMARK sensor is also available in a voltage output version (200SS-V) for easy integration with electronic systems. In addition to all of the standard sensor features, this version includes: Datasheets 200SS Datasheet 200SS-V Datasheet |
WATERMARK Sensor, Handheld Meter, and graph of collected data (WATERMARK Monitor) |