Thyme belongs to herbal plants, the yield and quality of which depend on biological factors, agrotechnical procedures and the way of processing and storage. Basic factor differentiating the biological value of plants is fertilization, including manure, as well as plant growth and development, which is significantly influenced by the pH ofthesubstrate, in which the plants are grown. The aim of the study was to determine the effect of manure dose (12.5 and 25 g·dm–3) and calcium carbonate (5 and 15 g·dm–3) on the yield and biological value of thyme. The fresh thyme mass yield was changed under the influence of the factors used. The highest yield of raw material was recorded after using a high dose of manure and calcium carbonate. Significantly higher concentration of essential oil in thyme was found after feeding the plants with higher dose of manure. The inverse relationship was demonstrated for the amount of L-ascorbic acid that decreased with the increase in manure dose. Calcium fertilizers not only serve to regulate the acidity, but are also a source of calcium for plants. After applying a higher dose of CaCO3, significant increase in the yield of fresh thyme mass was observed and higher dry matter content was recorded.