Influence of temperature on soil water content measured by ECH2O-TE sensors
The aim of this study was to investigate the influence of temperature on water content value measured by ECH2O-TE sensors. The influence of temperature on measured soil water content values was clearly demonstrated. Soil water content values measured during the day apparently oscillated with oscillating soil temperatures. Average daily temperature and soil water content were calculated for selected periods. Regression relationships between deviations of soil temperature and soil water content from their daily average values were evaluated. Correlation between the soil water content and temperature deviations increase with the soil depth due to the lower influence of rainfall and evaporation at the soil surface on measured soil water content values in deeper soil layers eg soil water content oscillation was controlled mostly by oscillating temperature. The guideline values of linear regression equations (R2>0.8) were very similar, close to value 0.002 and the intercept values were equal to zero. The equation for recalculation of measured soil water content values at given temperature to reference soil water content for reference soil temperature, was propozed on the basis of this analysis.
Campbell C. S., 2002. Response of ECH2O soil moisture sensor to temperature variation, Decagon Application Note, http.//www.degacon.com http://www.degacon.com
Chandler D. G., Seyfried M., Murdock M., and McNamara J. P., 2004. Field calibration of water content reflectometers. Soil Sci. Soc. Am. J., 68, 1501-1507.
Chen Y. and Or D., 2006. Geometrical factors and interfacial processes affecting complex dielectric permittivity of partially saturated porous media. Water Resour. Res., 42, W06423 9 PP., doi:10.1029/2005WR004744.
Czarnomski N. M., Moore G. W., Pypker T. G., Licata J., and Bond B. J., 2005. Precision and accuracy of three alternative instruments for measuring soil water content in two forest soils of the Pacific Northwest. Can. J. For. Res., 35, 1867-1876.
Dane H. and Topp G. C., 2002. Methods of Soil Analysis. Part 4. Physical Methods. SSSA Press, Madison, WI, USA.
Evett S. R., Tolk J. A., and Howell T. A., 2006. Soil profile water content determination: Sensors accuracy, axial response, calibration, temperature dependence, and precision. Vadose Zone, 5(3), 894-907.
Friedman S. P., 2005. Soil properties influencing apparent electrical conductivity: a review. Computers Electronics Agric., 46(1-3), 45-70.
Guber A. K., Pachepsky Y. A., Rowland R., and Gish T. J., 2010. Field correction of the multisensor capacitance probe calibration. Int. Agrophys., 24, 43-49.
Kizito F., Campbell C. S., Campbell G. S., Cobos D. R., Teare B. L., Carter B., and Hopmans J. W., 2008. Frequency, electrical conductivity and temperature analysis of a low-cost capacitance soil moisture sensor. J. Hydrol., 352, 367-378.
Kodešová R., Kočárek M., Kodeš V., Drábek O., Kozák J., and Hejtmánková K., 2011a. Pesticide adsorption in relation to soil properties and soil type distribution in regional scale. J. Hazard. Materials, 186, 540-550.
Kodešová R., Kodeš V., and Mráz A., 2011b. Comparison of two sensors ECH2O EC-5 and SM200 for measuring soil water content. Soil Water Res., 6(2), 102-110.
Mead R. M., Soppe R. W. O., and Ayars J. E., 1996. Capacitance probe observations of daily soil moisture fluctuations., Proc. Int. Conf. Evapotranspiration and Irrigation (Eds C. J. Camp, E. J. Sadler, R. E. Yoder). November 3-6, San Antonio, TX, USA.
Noborio K., 2001. Measurement of soil water content and electrical conductivity by time domain reflectometry: a review. Computers Electronics Agric., 31(3), 213-237.
Or D. and Wraith J. M., 1999. Temperature effect on soil bulk dielectric permittivity measured by time domain reflectometry: Aphysical model. Water Res. Res., 35(2), 371-383.
Ruth B. and Munch J. C., 2005. Field measurements of the water content in the top soil using a new capacitance sensor with a flat sensitive volume. J. Plant Nutr. Soil Sci., 168, 169-175.
Seyfried M. S. and Murdock M. D., 2001. Response of a new soil water sensors to variable soil, water content, and temperature. Soil Sci. Soc. Am. J., 65, 28-34.
Seyfried M. S. and Murdock M. D., 2004. Measurement of soil water content with a 50 MHz soil dielectric sensor. Soil Sci. Soc. Am. J., 68, 394-403.
Skierucha W., 2009. Temperature dependence of time domain reflectometry-measured soil dielectric permitivity. J. Plant Nutr. Soil Sci., 172, 186-193.
Topp G. C., Davis J. L., and Annan A. P., 1980. Electromagnetic determination of soil water content: measurements in coaxial transmission lines. Water Resour. Res., 16, 574-582.
Verhoef A., Fernández-Gálvez J., Diaz-Espejo A., Main B. E., and El-Bishti M., 2006. The diurnal course of soil moisture as measured by various dielectrid sensors: Effect of soil temperature and the implication for evapotranspiration estimates. J. Hydrol., 321, 147-162.
Wraith J. A., Robinson D. A., Jones S. B., and Long D. S., 2005. Spatially characterizing apparent electrical conductivity and water content of surface soils with time domain reflectometry. Computers Electronics Agric., 46(1-3), 239-261.
Wraith J. M. and Or D., 1999. Temperature effects on soil bulk dielectric permittivity measured by time domain reflectometry: Experimental evidence and hypothesis development. Water Res. Res., 35(2), 361-369.