Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 9/4/2001
Publication Date: N/A
Citation: Interpretive Summary: Modern agriculture has need for on-line moisture sensing in grain, seed, and other agricultural products. For grain and seed, knowledge of their moisture content is crucial for safe storage and prevention of spoilage, with, in some instances, production of toxins detrimental to human and animal health as a result of mold growth. Reliable on-line monitoring of grain and seed moisture is also important for reliable yield mapping in precision agriculture applications. Research has shown that certain mathematical functions of the microwave dielectric properties of grain (the electrical characteristics that affect the interaction of microwaves with the grain) are useful for moisture sensing. Two of these functions, which can be used for moisture content sensing, were studied to determine how their performance varied with the frequency of the microwaves used and with changes in temperature of the grain. New information was obtained concerning frequency selection for moisture sensing by microwave measurements and the dependence of the moisture calibration functions on temperature. These are two important factors to take into consideration in designing microwave grain moisture sensing equipment. The effects of temperature on moisture sensing need to be taken into account in calibrating such instruments. The development of moisture sensing instruments based on these and other research findings will provide new tools to better maintain grain and seed quality, to improve fairness in the grain trade, and to permit more efficient processing and improved products.
Technical Abstract: The frequency and temperature behavior of two density-independent permittivity-based calibration functions are discussed for a microwave moisture sensor operating on the principle of free-space permittivity measurement. Frequency selection and the need for temperature compensation for optimum use of the instrument capabilities are demonstrated through permittivity measurements on wheat and soybeans over wide ranges of frequency, temperature, bulk density and moisture content.