Performance Comparison of Rf Impedance and Dc Conductance Measurements for Single-Kernel Moisture Determination in Corn

Two electrical measurement techniques for rapidly detemiining the moisture content of individual kernels of com, Zea mays L., were compared directly with an oven drying reference method. One was a dc conductance measurement on kernels as they passed between cmshing-roller electrodes. The other involved a radio-frequency (RF) complex impedance measurement on a parallel-plate capacitor with the kemel between the plates. Twenty-kernel samples from bands around the corn ear, near the butt, midsection, and tip, were measured from ears of several moisture levels ranging between 12 and 40%, wet basis, for four yellow-dent field com hybrids that dried naturally in the fields in Illinois and Nebraska. Both techniques provided reliable kemel moisture contents, independent of kemel size, with standard errors of performance of 0.6 and 0.7% moisture content for the cmshing-roller conductance and parallel-plate impedance methods, respectively, and can therefore be recommended for practical application. KEYWORDS. Com, Moisture content.