A prototype infrared reflectance moisture meter

Abstract Novel solid state devices which emit radiation at wavelengths of 1·30 μm and 1·45 μm have been used as radiation sources in a prototype instrument to estimate moisture content from the ratio of the diffuse reflectances at these two wavelengths. A Motorola 6802 microprocessor controls the measurement cycle and calculates the average ratio of reflectance from the two sources. The instrument completes 700 measurement cycles per second and can give a virtually instantaneous estimate of moisture content. Measurements with chopped Sabrina ryegrass are described which demonstrate the relationship between the diffuse reflectance ratio and moisture content over the range of 20–80% (wet basis).