FDR(Frequency Domain Reflectometry)———频域反射仪是一种用于测量土壤水分的仪器,这是一种利用电磁脉冲方法,根据电磁波在介质中传播速度来测试介质的介电常数从而测定土壤水分的仪器。通过介绍FDR系统在高山草甸土上的校正结果,研究表明,野外校正比较符合实际情况,可以作为青藏高原地区高山草甸土进行FDR校正的参考。由于具有快速、准确等优点,能自动、连续地监测土壤含水量,FDR是一种值得推广的土壤水分测定仪器。

FDR(Frequency Domain Reflectometry) is a type of equipment for measurement of soil water content.The travelv elocity of electromagnetic wave is determined by the dielectric constant,and the dielectric constant of soil is determined by the soil water content.FDR can measure the soil water content by measure the travel velocity of electromagnetic wave.A set of FDR system and its measurement of in alpine meadow soil are introduced.Calibration for FDR measurement was done in the field.The result shows that the calibration has to be done and the field calibration is practicable,and the prediction equation can be used in alpine meadow soil other area of the Tibetan Plateau.Because FDR can measure soil water content automatically and continuously,this method is recommendable.