【摘要】 试验通过往土壤中加入电介质溶液 ,以及在不同粘粒含量土壤上用时域反射仪 (TDR)测定土壤含水量 ,研究结果表明 :在较低含水量情况下 (砂土 <0 1 5cm3cm- 3,砂质壤土 <0 .1 8cm3cm- 3) ,电导率的增加不易引起TDR测定值的明显偏差 ;但在较高含水量下 ,当溶液电导率增加到 8dSm- 1 (砂质壤土 )和 1 1dSm- 1 (砂土 )时 ,TDR测得的含水量值明显高于实际值。在较高电导率 ( <1 6dSm- 1 )下 ,K0 .5a 与实际含水量仍呈较好的线性关系 ,但电导率引起的介电损失影响了K0 .5a ～θ线性关系的斜率和截距。本文给出了考虑电导率影响的K0 .5a ～θ线性关系的校正方程。土壤粘粒含量的增加也会引起TDR测定偏差 ,在低含水量时测定值偏低 ,在高含水量时测定值偏高。粘粒含量 <5 0 %时 ,测定偏差 <0 .0 2cm3cm- 3。更多还原

【Abstract】 Time domain reflectometry (TDR) is widely used in determining water content for general agricultural soils. But for soils with high bulk electrical conductivity, such as saline soils or heavy clay soils, the TDR measurement was not ideal because of dielectric losses. Based on experiments, this work intended to explain the phenomenon of TDR measured value deviating from actual water content. The result showed: when the water content was low (sand, <0.15cm 3 cm -3 ; sandy loam, <0.18 cm 3 cm -3 ), increasing electrical conductivity was not linely to induce a higher measured value. While the water content was high and the electrical conductivity up to 8 dS m -1 (sandy loam) and 11 dS m -1 (sand), TDR measured value was apparently higher than the actual water content. In the case of higher electrical conductivity (<16 dS m -1 ), K a was still in linear correlationship with the actual water content, while the slope and intercept were influenced by dielectric loss. In this study, a calibration equation was set up, considering the influence of electrical conductivity was set up. The increase in soil clay particle content also induced TDR measurement deviation. When the soil water content was low, the measured value was lower, and when the soil water content was high, the measured value was higher. If the clay content was <50%, the measured error would be <±0.02cm 3 cm -3 .更多还原