Continuously measurement of the dry matter content using near-infrared spectroscopy

Abstract

Near-infrared spectroscopy (NIRS) was used in agriculture and food chemistry in the early 1960s. NIR is located at a wavelength range between 800 nm and 2,500 nm. Although NIRS technology is a rapid, repeatable, highly precision and environmentally friendly technology for recording of spectra without destroying the samples, it is a complex method and the spectrometer calibration with a validated primary reference analysis is required. This study aimed at testing the suitability of NIRS for documenting the dry matter (DM) content of the stored silage in plastic bags. Accordingly NIRS sensors were installed in a commercial silo bagging machine after preliminary experiments in small scale were done. Maize and grass silage DM content was detected continuously using NIRS during storage process. The mean reference values for maize silage were significantly 6.6% higher than the NIRS values. With grass silage, NIRS values were only 0.6% below the mean reference value. The results of the NIRS sensor in the grass silage bag were less uniform than those of the maize silage due to no continuous direct contact between the measuring window and the substrate. NIRS sensor proved generally to be a suitable means of determining the DM in the crop flow of the pressing machine. However, continuous contact between the ensiled material and the NIRS sensor must be ensured, to guarantee that measurements are correct.