Submitted to: Institute of Electrical and Electronics Engineers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2000
Publication Date: 3/1/2000
Citation: NELSON, S.O., KRASZEWSKI, A.W., TRABELSI, S., LAWRENCE, K.C. USING CEREAL GRAIN PERMITTIVITY FOR SENSING MOISTURE CONTENT. INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS. 2000. Interpretive Summary: Moisture content of cereal grains is the most important characteristic determining proper time for harvest, safe storage potential, transportability, trading price, and quality and suitability for further processing. Moisture content is currently determined rapidly and nondestructively by electronic moisture meters that utilize the correlation nbetween electrical properties of grains, known as dielectric properties or permittivity, and the amount of moisture in the grain. These moisture meters work well for batch samples of grain taken from trucks, barges, elevator storage, shipping lots, etc., but attempts to use the same principles for sensing grain moisture content in flowing or moving grain to provide continuous moisture monitoring have not been as successful as desired in providing accurate moisture contents. Recent research has shown promise for eliminating the errors associated with moving grain measurements attributable to changes in the packing density of the granula materials as they flow. Several of the newly discovered techniques found useful for improving the accuracy of moisture sensing in moving grain are explained. These new methods should provide the basis for the development of reliable on-line monitoring instruments that can provide continuous moisture content information that will be helpful in maintaining high quality in grains and grain products and provide reliable moisture information needed for accurate yield determinations on combines employing precision agriculture technology.
Technical Abstract: A brief history of cereal grain moisture measurement by sensing the electrical properties of grain is presented. The basic principles are also described for using radio-frequency (RF) and microwave dielectric properties, or permittivity, of grain for sensing moisture through their correlation with moisture content. The development of density-independent functions of the permittivity is explained. The findings of recent research are summarized, which indicate that reliable density-independent moisture content determinations can be realized by measurements on grain at RF and microwave frequencies. Development of these techniques will provide useful instruments for on-line monitoring of moisture content in flowing grain to manage moisture in grain, prevent spoilage in storage and transport, improve processing, and provide information important for yield determinations in precision agriculture applications.