The EQ3 Equitensiometer (EQ3) measures soil matric potential and temperature. Soil matric potential is the negative pressure (or suction) required to extract water from between the matrix of soil particles. It is an important indication of plant water stress. The value of soil matric potential measured depends mainly on the quantity of water present and the make-up of the soil, though it is also affected by temperature and salinity.
The EQ3 consists of a precision soil moisture sensor (the ML3 ThetaProbe) whose measuring rods are embedded in a porous material (the equilibrium body). This material has a known, stable relationship between water content and matric potential. When the probe is inserted into the soil, the matric potential within the equilibrium body equilibrates to that of the surrounding soils. The water content of the matric material is measured directly by the ML3 ThetaProbe, and this can be converted into the matric potential of the surrounding soil using the calibration curve supplied with each Equitensiometer.
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Matric Potential
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Accuracy
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±10kPa over 0 to -100kPa,
±5% of reading over -100 to -1000kPa
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Measurement range
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0 to-1000kPa (-10bar)
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Hysteresis
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Not detectable if the change of matric potential is slower than 0.1kPa/min.
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Soil Types
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Suitable for all non-saline soil types
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Output Signal
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0-1V differential, non-linear. (Calibration data and graph supplied with each sensor)
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Output compatible with
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GP1, GP2, DL6, DL2e, HH2
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Temperature
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EQ3 must be fully buried to accurately measure soil temperature
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Sensor accuracy
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±0.5°C over 0-40°C
not including logger or cabling error
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Output
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Resistance: 5.8kOhm to 28kOhm
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Output compatible with
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GP1, GP2, DL65, DL2e, HH2
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Cabling error contribution (to temperature readings)
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Negligible for GP1, GP2 & DL6 (any cable length)
Negligible for DL2e (with 5m cable)6
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Maximum cable length
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100m (GP1, GP2 & DL6 data loggers)
100m (DL2e: water content measurement)
25m (DL2e: temperature measurement)
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Power requirement
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5-14VDC, 18mA for 0.5 to 1s
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Operating range
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-0 to +40°C (Not damaged by use in frozen soils)
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Environment
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IP68
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Dimensions/weight
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