The Effect of Fertilization with Spent Mushroom Substrate and Traditional Methods of Fertilization of Common Thyme (Thymus vulgaris L.) on Yield Quality and Antioxidant Properties of Herbal Material

This experiment was designed to determine the effect of spent mushroom substrate, farmyard manure, and mineral fertilization with nitrogen, phosphorus, and potassium on the yield and quality of raw material obtained from two cultivars (“Sloneczko” and “De Dolj”) of common thyme. Unfertilized plots with thyme crops were included as the control treatment. Different row spacings (30 cm and 40 cm) represented the second experimental factor. The highest total yield of thyme raw material was found in the treatment with mineral NPK fertilization, but also in the treatments where spent mushroom substrate (SMS) and mineral NPK fertilization were applied at a ratio of 50:50%. Fertilization with SMS alone (100%) yielded smaller production effects, but they were higher than in the case of fertilization with manure. The high suitability of spent mushroom substrate applied alone or supplemented with mineral fertilization at different rates in spring was confirmed by the best quality parameters and antioxidant properties of the raw material. The use of a wider row spacing (40 cm) resulted in a higher yield of thyme raw material than in the case of a narrower one (30 cm). The narrower row spacing significantly positively affected some of the analyzed quality parameters of the harvested raw material, such as: essential oil content, polyphenol content, and antioxidant activity. The thyme cultivar “Sloneczko” proved to be absolutely more beneficial in terms of yield quantity and quality than the foreign cultivar “De Dolj”.