Monitoraggio del contenuto idrico del suolo mediante riflettometria

Currently the most diffused methods to measure soil water content allow only "punctual" measurements and there are, therefore, problems of data spatialization to estimate the moisture of large volumes of soil. Also instruments for Time Domain Reflectometry (TDR), because of the short probes used (maximum 0.5 m), provide data related to small volumes of soil. In this chapter the aspects which have not allowed, up to now, the use with TDR of longer probes are analysed. Specific solutions are proposed which allow execution of reflectometry using long bifilar line probes (more than three meters), making it possible to obtain indications of average values of soil moisture without having to effectuate TDR measurements in different points and then calculate the average value. Comparison between measurements carried out, in the same soil, with a punctual TDR probe and with a gravimetric method (reference method) shows variances that can arrive at 50 %. The proposed method, in addition to allowing the estimation of moisture of a large volume of soil, associates the simplicity of the probe (bifilar lines with parallel conductors) with ease of use and good accuracy.