Investigation of the Effect Soil particles size on the Currency Time Domain Reflectometry for water content measurement

Subject Areas : Irrigation and Drainage

عیسی معروف پور ¹ , مینا بهزادی نسب ²

1 - دانشگاه کردستان، گروه مهندسی آب، کردستان، ایران.
2 - شرکت آب منطقه‌ای کردستان،کردستان، ایران.

Received: 2012-03-26 Accepted : 2012-06-17 Published : 2012-06-20

Keywords: Calibration, بافت خاک, TDR, Soil texture, کالیبراسیون,

Abstract :

This study carried out on the provided textures at laboratory. The provided textures were infusedinside the PVC cylinder with 30cm height and 25cm diameter. The studied textures were loamysand, sandy loam, sandy clay-loam, clay loam and clay. After 24 hours of saturation, the soil watercontent of the samples was measured by oven-dry gravimetric and TDR methods. For each texturesat any stage of measurement the determination of moisture and di-electric constant were done atthree capture windows and with three repetitions. In each day the moisture measurement of eachtexture was carried out by these two methods until a moisture range was determined. The results ofthis research show that: 1- For all soil textures the measured moisture at the capture windows of 20ns has more accuracy compared to the other capture windows. and TDR device can not measure thesoil water content at capture window of 40 ns. 2- For loamy-sand and sandy-loam textures when themoisture was less than 20% and also for other textures for total range of measurement, the TDRdevice measured the moisture values less than the gravimetric method. This difference is increasedwhen the soil ranged from light to heavy textures. 3- From the statistical view at probably level of1% there is not difference between the measured value of moisture by TDR device and gravimetricmethod. 4- For the all textures the fitted regression lines have high regression coefficient.

References:

Birang, N. E. and Maule, C. (2003). Calibration of a Instrument for Simultaneous Measurements of Soil Water and Soil Electrical Conductivity.Written for Presentation at the 2003 CSAE/ASAE Annual Intersectional Meetting Sponsored by Red River Section of ASAE Quality Inn and Suites 301 3rd Avenue North Fargo ,North Dakota,USA.

Chandler, D.G., Sayfried, M., Murdock, M. and Mcnamara, J.P. (2004). Field Calibration of Water Content Reflectometers. Soil Sci. Soc. Am. J., 68: pp.1501-1507.

Dalton, F.N. (1992). Development of time-domain reflectometry for measuring soil water content and bulk soil electrical conductivity. Advances in Measurement of Soil Physical Properties: Bringing Theory into Practice. pp143-168.

Dasberg, S. and Hopmans, J.W. (1992). Time domain reflectometry calibration for uniformly and nonuniformly wetted sandy and clayey loam soils. Soil Sci. Soc. Am. J., 56:pp. 1341-1345 .

Dehghanisanij, H., Yamahato, T. and Inoue, M. (2004). Practical Aspects of TDR for Simultaneous Measurements of Water and Solute in a Dune Sand Field. J. Jpn. Soil Phys., 98:pp. 21-30.

Dirksen, C. and Dasberg, S. (1992). Improved calibration of time-domain reflectometry soil water content measurements. Sci. Soc. Am. J., 57:pp. 660-667.

George, B. H.(2000). Comparison of techniques for measuring the Water content of soil and other porous media. Theses (M.SC). Sydney University, Department of Agricultural Chemistry and Soil Science, Sydney, Australia.

Jacobsen, O .H. and Schjonning, P. (1993b). Field evaluation of time-domain reflectometry for soil water measurements. Journal of Hydrology, 151:pp. 159-172.

Liaghat, A. and Broughton, R.S.( 1993). Effect of clay type and clay content on moisture content and bulk soil electrical conductivity as measured using time domain reflectometry. THESES (M.SC) Mcgill university , Dept. of agricultural engineering, Montreal, Quebec, Canada.

Nadler, A., Dasberg, S. and Lapid, I.(1991). Time domain reflectometry measurements of water content and electrical conductivity of layered soil columns. Soil Sci. Soc. Am. J., 55:pp.938–943.

Persson, M. and Berndtsson, R. (1998). Texture and electrical conductivity effects on temperature dependency in time domain reflectometry. Soil Sci. Soc. Am. J., 62:pp 887-893.

Ponizovsky, A. A., Chumdinova, S.M. and Pachepsky,Y.A.( 1999). Performance of TDR calibration models as affected by soil texture. Journal of Hydrology, 218:pp. 35-43

Quanghee, Y., Drnevich, V. P., Siddiqui, S. I. and Lovell, J.( 2001). Effects of Testing Large Particle-Sized Materials. Second International Symposium and Workshop on Time Domain Reflectometry for Innovative Geotechnical Applications. pp470 – 482.

Roth, K., Schulin, R., Fluhler, H. and Attinger, W. (1990). Calibration of time-domain reflectometry for water content measurement using a composite dielectric approach. Water Resources Research, 26:pp. 2267-2273.

Siddiqui, S. I., Drnevich, V.P. and Deschamps, R.J. (2000). Time Domain Reflectometry Development for Use in Geotechnical Engineering. Geotechnical Testing Journal, 23(1): 9-20.

Souza, C.F., Matsura, E.E. and Testezlaf, R. (2001). Aplication of time domain reflectometry technique in tropical soil. Second International Symposium and Workshop on Time Domain Reflectometry for Innovative Geotechnical Applications. pp.273-280 .

Topp, G.C., Davis, J.L. and Annan, A.P. (1980). Electromagnetic determination of soil water content: Measurement in coaxial transmission lines. Water Resources Research, 16: pp.574–582.

Topp, G.C. and Davis, J.L. (1985). Time domain reflectometry (TDR) and its application to irrigation. In "Advances in Irrigation". Academic Press, NewYork, PP.107-127

Walker, J.P., Willgoose, G.R. and Kalma, J.D. (2004). Insitu measurement of soil moisture: a comparison of techniques. Journal of Hydrology, 293:pp. 85-99