Humidity Sensor, digital and analog to measure air and soil moisture



Equitensiometer measures matric soil water potential, defined as the amount of work that must be done per unit quantity of pure water in order to transport reversibly and isothermally an infinitesimal quantity of water; identical in composition to the soil water, from a pool at the elevation and the external gas pressure of the point under consideration, to the soil water (Glossary of Soil Science Terms, Soil Science of America (SSSA), July 1987). If the specified quantity is volume, the potential is referred to as pressure (Pascal). Matric soil water potential is the main component of total soil water potential. In the not salt soil the total water potential is equal to the matric water potential.

There are important differences between water content and water potential. The water contents describe the amount of water in a soil, but not the availability of the water for plants. Plants would grow in a sand soil with 10% vol./vol. very well. But in a clay soil with the same water content the most plants would not survive because of drying. Studies on soil water- plant - relationship need, therefore, the water availability, and this is the water potential.

In comparison with known methods the Equitensiometer has following advantages:

  1. Wide measuring range: 0 to  -1 500 kPa (0 to -15 bar)
  2. Highly accurate: error<5 kPa (5%)
  3. Absolutely maintenance free, without any of familiar tensiometer problems
  4. Independent measurements on soil properties
  5. Easy operation
  6. suitable for outdoor use
  • Technical Specification
  • Variations
  • Measured variable: Matrixpotential
  • Measuring range: 0... -1 500 kPa (0 to -15 bar)
  • Accuracy: From 0... - 100 kPa: ± 5 kPa
    From –100... -1500 kPa: <5% of the measured values
  • Hysteresis: Very low, similar as transducer tensiometers
  • Power consumption: Voltage: 5...15 V DC, Current: max. 23 mA, Duration: 10 Sec per measurement
  • Output: 0-700 mV (can be connected directly to the Combilog 1020 and 1022)
  • Dimensions and Weight: 170 x 40 x 20 mm, Weight 350 g (without cable)
  • Cable length: 5 m (other lengths up on request)
  • note 3505.2000Equitensiometer
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Patent-registered measuring method to define the matrixpotential of the soil