Evaluation of moisture meters suited for developing countries

Cost-effective measurement methods are needed for monitoring stored grain quality that is feasible for smallholder farmers and villages in developing countries. The objectives of this study were to 1) evaluate several commercially available grain moisture meters for accuracy and precision and 2) indicate advantages and limitations of each meter (KSU-GT200, John Deere SW08120, Agratronix MT-16, DICKEY-john M3G, Hygrometer, Drycard) and 3) to assess the suitability of each meter for use in developing countries. Samples of corn, wheat, and paddy rice were prepared at various moisture content (MC) levels, and measurements were carried out complying with manufactures instructions. At each MC and for each grain, readings were taken three times using three replicate grain samples. Procedures ensured uniform mixing prior to the use of each method. As a reference, actual moisture content was determined using a standard oven method. For the Dry Card (cards coated with a sensitive chemical that reacts to humidity) and hygrometer methods, repeatability was indicated using additional grain samples that are near the “go, no go” relative humidity specified by the manufacturer. At 14.5 % moisture content, John Deere SW08120 measured moisture content with the highest repeatability. Minimum and maximum difference (% moisture content) from oven results were 0.1 (KSU-GT200) and 3.7 (DICKEY-john), respectively. Measurements for paddy rice at higher MC levels (above 15% w.b.) were accurate (± 0.1% w.b.).