Soil-water content measurement is critical for irrigation research and management. Time domain reflectometry (TDR) is among the newly developed methods for determination of soil-water content which relies on the relation between the soil dielectric property and water content. In order to obtain a soil water content profile, a large number of wave guides is necessary which raises the cost. On the other hand, calibration curves relating dielectric capacity to soil-water content have been developed mainly for soils of temperate regions. The objectives of this work were the development of a buriable wave guide using available materials and its calibration for tropical soils. Calibration curves developed for Psament and Haplustox soils are distinct and different from those found in the literature. A modification of a physically-based mathematical model fits well to the data of each soil type independently.
instrumentation; water content; irrigation
