One of the most important fractions of soil organic matter which has significant environmental and agricultural importance is humus. The effectiveness of the natural formation of active humic substances during composting processes depends on the chemical composition the chicken manure of organic residues and on the environmental conditions influencing the development and activity of native microorganisms. The organic compounds contained in the compost or formed as decomposition products of other compounds are subject to the resynthesis process thanks to the thermophilic microorganisms, creating humus, which is the main component of the soil. In the fertilizer obtained after 7 days of composting with the use of KOMPRE, the total content of active humic substances is up to 45%, of which 16 to19% are fulvic acids and 21 to 26% humic acids. It is an easily digestible, complex organic fertilizer of brown and black colour, pH 7.5-8.0 and NPK 5: 3: 4.

Biological tests with the use of cress (Lepidium sativum L.) were conducted, aimed at determining the effect of water extracts from differently matured composts on the germination of cress seeds. The plant germination and growth tests were carried out on the basis of the applicable standard (PN – EN ISO 11269–1: 2013–06). Aqueous extracts prepared in the proportion of compost and distilled water were used to assess the germination power and development of cress seedlings. In phytotoxicity tests, different doses of the fertilizer from 1g/L to 10g/L were tried to determine whether the obtained product after composting did not contain any substances that inhibit germination and the initial growth and development of Lepidium sativum L. plants. It is clear that no toxic effects were recorded.