Soil moisture/Electric Conductivity - FDR (WET Sensor)

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Wetsensor.jpg

Contents

Parameter to be measured:

  • Soil moisture, permittivity
  • Indirect measurement of electric conductivity of pore water
  • Temperature

Method:

Frequency Domain Sensor

Equipment:

  • Delta-T Device: WET Sensor with 3 rods of 600 mm length, HH2 display for manual reading or a data logger

Advantages:

  • easy and fast measurement of punctual soil moisture and electric conductivity of soil pore water
  • manual as well as continuously logged measurements possible

Disadvantages:

  • Each sensor has to be calibrated
  • careful application of probe in stony soils
  • Underestimating of permitivity in media with low permitivity (ε > 40, clay and organic soils)
  • unaccurate values in saturated media

What to watch out for:

  • Good contact between probe and medium has to be proved

Problems/Questions:

Links

Other related web sites:

Delta-T Devices

References

  • Balendonck, J., Bruins, M.A., Wattimena, M.R., Voogt, W., Huys, A. (2005): WET-sensor pore water EC calibration for three horticultural soils, Acta Horticulturae 691, ISSN 0567-7572, 789 - 796.
  • Bouskila, F.,Persson, M., Berndtsson, R., Bahri, A. (2008), Soil water content and salinity determination using different dielectric methods in saline gypsiferous soil, HYDROLOG SCI J 53(1), 253-265.
  • Hamed, Y.,Samy, G., Persson, M. (2006), Evaluation of the WET sensor compared to time domain reflectometry, HYDROLOG SCI J 51(4),671-681.
  • Inoue, M., Ahmed, B.A., Saito, T., Irshad, M., Uzoma, K.C. (2008): Comparison of three dielectric moisture sensors for measurement of water in saline sandy soil, Soil Use and Management 24, 156–162, DOI: 10.1111/j.1475-2743.2008.00154.x.
  • Kargas, G., Kerkides, P*, Seyfried, M, Sgoumbopoulou, A (2011): WET Sensor Performance in Organic and Inorganic Media with Heterogeneous Moisture Distribution, Soil Science Society of America Journal 75(4), 1244-1252, DOI: 10.2136/sssaj2010.0238.
  • Regalado, C.M., Ritter, A., Rodriguez-Gonzalez, R.M. (2007), Performance of the commercial WET capacitance sensor as compared with time domain reflectometry in volcanic soils, VADOSE ZONE J 6(3), 1539-1663.
  • Wu, J., Li, P., Qian, H., Fang, Y. (2014), Assessment of soil salinization based on a low-cost method and its influencing factors in a semi-arid agricultural area, northwest China, Environ Earth Sci., 71, 3465–3475, DOI: 10.1007/s12665-013-2736-x.
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