Performance of three types of soil moisture sensors:SWR,TDR and FD

Soil moisture sensors based on principles of Time Domain Reflectometry(TDR),Frequency Domain(FD) and a new type of soil moisture sensor based on Standing Wave Ratio(SWR) developed by China Agricultural University were evaluated with typical sandy loam,loess,peaty sand and leady loam from northern Germany.An analysis of variance of the experimental data suggested that the SWR soil moisture sensor has the highest precision,the greatest dependability and is influenced only slightly by soil quality. SWR-based sensors' performance is compared favorably to TDR and FD soil moisture sensors.