The Model LT IRROMETER was designed to effectively measure the very wet end of the soil.
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.
*** One Service Unit is required to make the Irrometers work correctly. *** (One Service Unit is sufficient for multiple Irrometers.) The MLT use the SU1007 and the LT Models use the SU1001. Click here.
How Measuring Soil Moisture Works
Measuring soil moisture for growing purposes is typically done in one of two ways:
- Volumetric measurement, the percentage of water in a given amount of soil.
- Tensiometric measurement, the physical force actually holding water in the soil, measured in Centibars (or kPa) of soil water tension.
IRROMETER soil moisture measurement is based on the tensiometric method, because of the fact that the amount of water is not as important as how difficult it is for the plant to extract it from the soil.
Soil water tension (or matric potential) has to be overcome for the plant to move water in to its root system. Different soil types will have different tensions even at the same volumetric measurement, making volumetric information relative to local conditions and often requiring site calibration for reading equipment. Because we use soil water tension, there is no site calibration required when using our sensors.
Due to the fact that tensiometers have been used in research since the 1920's and have been commercially available (from the IRROMETER Company) since 1951, years of published research by numerous universities and extension agencies have produced a wide field of reference for recommended tension levels to use with common crops and landscapes. Soil moisture information provided by IRROMETER equipment is inexpensive, accurate, and relevant.
Irrometer's Soil Moisture Meters Brochure
https://www.irrometer.com/pdf/101.pdf
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