INRA, UMR 1114 Environnement Méditerranéen et Modélisation des Agro-Hydrosystemes, Site Agroparc, 84914 Avignon Cédex 9, France.
Sensors (Basel). 2012;12(7):9773-90. doi: 10.3390/s120709773. Epub 2012 Jul 18.
The influence of temperature on the dielectric permittivity of soil is the result of counteracting effect that depends on the soil's composition and mineralogy. In this paper, laboratory experiments showed that for a given water content, the soil dielectric permittivity was linearly related to the temperature, with a slope (α) that varied between samples taken in the same soil. These variations are difficult to predict and therefore, a simple and straightforward algorithm was designed to estimate α based on the diurnal patterns of both the measured dielectric permittivity and the soil temperature. The underlying idea is to assume that soil water content variations can be known with a reasonable accuracy over an appropriate time window within a day. This allows determining the contribution of the soil water content to the dielectric permittivity variations and then, the difference with the observed measurements is attributed to the soil temperature. Implementation of the correction methods in a large number of experiments significantly improved the physical meaning of the temporal evolution of the soil water content as the daily cycles for probes located near the surface or the long-term variations for more deeply installed probes.
温度对土壤介电常数的影响是一种相互抵消的效应，取决于土壤的组成和矿物学。本文的实验室实验表明，对于给定的含水量，土壤介电常数与温度呈线性关系，斜率（α）在同一土壤中采集的样本之间有所不同。这些变化很难预测，因此，设计了一种简单直接的算法，根据测量的介电常数和土壤温度的日变化模式来估计α。其基本思想是假设在一天内的适当时间窗口内，可以以合理的精度了解土壤水分含量的变化。这可以确定土壤水分含量对介电常数变化的贡献，然后，将观察到的测量值与土壤温度的差异归因于土壤温度。在大量实验中实施的校正方法显著提高了土壤水分含量的时间演变的物理意义，因为位于表面附近的探头的日循环或更深入安装的探头的长期变化。
