The measurement of soil water content and available water levels by TDR (time domain reflectometry) and the calibration of the tool in various soil texture classes

ABSTRACTMSc THESISTHE MEASUREMENT OF SOIL WATER CONTENT AND AVAILABLEWATER LEVELS BY TDR (TIME DOMAIN REFLECTOMETRY) ANDTHE CALIBRATION OF THE TOOL IN VARIOUS SOIL TEXTURECLASSESYusuf TÜLÜNDEPARTMENT OF SOIL SCIENCEINSTITUTE OF NATURAL AND APPLIED SCIENCEUNIVERSITY OF ÇUKUROVASupervisor: Prof. Dr. Alhan L. SARIYEVYear: 2005, Pages: 78Jury: Prof. Dr. Alhan L. SARIYEVAsist. Prof. Dr. smail ÇEL KAsist. Prof. Dr. Veysel POLATIn this study, the calibration of TDR (Time Domain Reflectometry) tool that isused recently commonly on the determination of soil water content that its determinationis a basic need in the studies of soil hydrology, agricultural and engineering areas wasconducted in different soil textures. For this reason, the samples that are in the categoryof prevalent textures (C, CL, SiC, SCL, L, SL, and S) in Çukurova region were takenand placed into the pots in respect to their bulk density. The calibration study with thegravimetric samples taken by TDR tool with the subsequent ones in various time periodsfrom the pots in question was carried out.As a result of the graphical evaluation of the calibration results, the real watercontents and TDR tool measurements were consistent with each other. Yet, in the case ofthe approach of the soil water content to the saturation levels, the tool did not result inthe correspondence results. Moreover, the increase of clay % and organic matter contentincreased the error in the measurements of the tool TDR.Keywords: TDR (Time Domain Reflectometry), Soil Texture, calibration, soil watercontent, available water