Quality Assessment of Growing Media with Near-Infrared Spectroscopy: Chemical Characteristics and Plant Assays

Quality control of growing media mainly consists of chemical analysis and plant assays, which are time-consuming and expensive. Objectives were to test, if near-infrared spectroscopy (NIRS) is capable to predict several chemical characteristics and plant as-say results for a large population of various peat-based growing media having a wide range of humification degrees and characteristics (n=320). Near-infrared measurements (including the visible range, 400– 2,500 nm) were done with fresh and with dried and ground growing media in order to predict their chem-ical characteristics and the results of plant assays using Chinese white cabbage (Brassica napus var. Chinensis). Spectral manipulations (taking 1st to 3rd derivative af-ter baseline correction), cross-validation and a modi