results indicate the lack of toxic effect of the tested fertilization doses on the germination of the test plants, with the exception of cress. There was, however a strong inhibition of seedling growth during 72 h in samples containing 10% of the tested fertilizers, especially when they showed significant salinity and high pH. The most sensitive species used for doses of fertilizer was cress, and the least sensitive was cucumber, for which there was a strong stimulation of root growth already at 5% share of tested fertilizer in the substrate. EI shows particular individual character of tested species using fertilizer based on SCG. The inhibition of wheat roots elongation was observed even in 2.5% fertilizers fare.Keywords Spent coffee grounds · SCG · Acute toxicity · Organic fertilizer · Sustainable agriculture
IntroductionSeparate collection of biodegradable waste fractions, carried out at its source, enables not only to channel it to the process of composting or biogas production, but also to obtain high-quality fertilizer. This also applies to the waste solvent extractable materials generated after the preparation of beverages from coffee beans. These wastes are formed in large quantities due to the increasing consumption of this beverage [1]. The annual coffee consumption in Poland has been increasing and currently stands at 3 kg per capita, however this is a number several times lower than in the Scandinavian countries. In large part these wastes are directed to biodegradable fraction containers. In practice, however, the containers contain significant amounts of non-compostable waste and, even if a compost is produced, its quality will be low.Abstract Sustainable agriculture places new demands on agricultural practice and, in particular, plant protection treatments and fertilization. Therefore, an increase in demand for organic fertilizers of good quality is expected. In particular, the organic matter contained in the waste of the food industry or generated in households, in the absence of contamination, can be used for the production of "fertilizer", which could be used in organic crop production. The paper presents basic characteristics of tested mixtures and the results of testing for acute toxicity of the mixture made from spent coffee grounds (SCG) modified with ash arising from the low-temperature combustion of biomass or magnesium sulphate and blood meal. The plant tests were conducted on: mustard (Synapis alba L.), wheat (Triticum sp. L.), cucumber (Cucumis sativus L.) and garden cress (Lepidium sativum L.).Toxicity tests were carried out using a standard 72 h procedure using the Phytotoxkit microbiotest platelet involving fertilizer 2. 5, 5 and 10% (v/v This causes not only the loss of organic matter, but also the time and effort necessary to carry out the composting process. Spent coffee grounds (SCG) material includes a wide range of valuable organic compounds which contain, among others, tannic acid, cellulose, hemicellulose, lipids, organic acids and polyphenols and therefore it is used for th...