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 chemical characteristics and the results of plant assays using Chinese white cabbage (Brassica napusvar. Chinensis). Spectral manipulations (taking 1st to 3rd derivative after baseline correction), cross-validation and a modified partial-least squares regression method were used to develop equations over the whole spectrum. Generally, NIRS predicted the chemical characteristics of growing media and the yields of fresh weight of Chinese white cabbage and rating better for fresh than for dried and ground samples. The pH and contents of total carbon and nitrogen, salt, P, K, mineral nitrogen, NO 3–, NH4+ and the NH4+ :NO 3 –ratio were predicted

---

• View source