Dielectric determination of moisture of cereals grain using time domain reflectometry

The usefulness of time domain reflectometry, TDR, for moisture of cereal grain was examined. TDR was applied to determine the moisture dependent relative dielectric constant, e, of the samples. A relationship between gravimetric moisture on wet basis, 6, and relative dielectric constant was investigated for wheat, rape, vetch, barley, Triticale and maize. Obtained results showed a linear 0(Ve) relationship, with intercept and slope varying from one species to another. Fitting a regression line to the 0(Ve) data set for each particular species resulted in a coefficient of regression R = 0.9959 and standard deviation SD = 0.0097 at best, and R = 0.9795 and SD = 0.0211 at worst case. Fitting the regression line to the aggregated 0(Vf) data set, comprising all species together, resulted in R = 0.9595 and SD = 0.0289. Thus, it was concluded that TDR could be a convenient technique to estimate the gravimetric moisture of grain with no specific calibration needed if readings of moderate accuracy were sufficient.