Highlights Measurements of complex permittivity were taken at microwave frequencies from 9 to 12 GHz. Dielectric properties were used in density-independent calibration for fresh poultry bedding moisture content determination in pine shavings and rice hulls. Standard error of calibration (SEC) was = 0.82% moisture content (wet basis) for moisture range 11%–27%. SEC was 0.43% moisture content (wet basis) for moisture range 11%–20%. ABSTRACT. Poultry houses use various materials including peanut shells, pine shavings, and rice hulls as bedding for the birds. Flocks introduce manure and excreta to the bedding, and the material is broken down as the birds walk over it. This causes its properties to change, and it is commonly referred to as poultry litter after this point. As more flocks are introduced to the litter, it breaks down such that it is hard to determine the original bedding material. One important physical property of poultry litter is moisture content, as it greatly affects the health of the birds. However, the low density of the fresh bedding and the changing density of the “used” litter make moisture content detection difficult with capacitance and NIR sensors. There currently isn’t a moisture sensor for repeatable, accurate measurements of fresh or used litter. Therefore, a network analyzer was used to take complex-permittivity measurements on pine shavings and rice hulls at microwave frequencies. The free-space transmission method was used to measure bulk samples varying in moisture content with a volume of 4800 cm 3 . Measurements were taken at 22°C between 9 and 12 GHz. Dielectric properties were determined and correlated with bedding moisture content by using a density-independent calibration function. The standard error of calibration (SEC) determined for wide moisture range, 11% to 27%, was = 0.82% moisture content wet basis (wb) for all bedding materials. The SEC improved to = 0.43% moisture content for a moisture range 11% to 20%. Results show promise in the application of microwave sensing to the accurate determination of moisture content in fresh poultry bedding. Keywords: Density-independent, Dielectric properties, Free-space transmission measurements, Microwave measurement, Moisture content, Poultry bedding.
Lewis et al. (Thu,) studied this question.