Parallel-plate moisture sensor for yellow-dent field corn

A Shielded parallel-plate moisture sensor was designed, calibrated, and val idated to sense the moisture content of yellow-dent field corn (Zea mays L. ). The sensor uses complex reflection coefficient measurements at about I, 40, and 140 MHz and sample weight to predict the moisture content of static corn samples at room temperature (similar to 22 degrees C) with a sample v olume of 850 cm(3). The sensor was calibrated with 29 corn samples of diffe ring hybrids, grown throughout the U.S. in 1997, with moisture contents ran ging from about 10% to 26% wet basis, The standard error of calibration was 0.24% moisture with a coefficient of determination of 0.997. The sensor wa s validated with 77 independent samples. The validation bias was 0.04% mois ture content and the standard error of prediction was 0.28% moisture conten t. The sensor performed slightly better than commercial moisture meters.