Using of unseparated digestate as a phosphorus source for garden plants

The advent of the modern trend of renewable resources was inevitable culmination of the development of civilization. Mankind learns more about use inexhaustible resources compared to depletion of reserves of non-renewable resources. Providers of renewable energy sources also include a biogas plant, which main function is the production of biogas. Biogas is produced in reactors by process of anaerobic fermentation without oxygen. As input for an agricultural biogas plants organic waste, cattle manure or for example energy grasses are used. The process of biogas production has the leftover of the fermentation at its end, so called digestate. Its composition depends especially on the inputs. Digestate is a compound with high pH which is very rich not only for phosphorus but also for other nutrients. There are many studies dealing with the theory and practice of using digestate on the field for improving its properties and of other digestate usage. This diploma thesis has aim to explore combinations of unseparated digestate with peat and dolomite limestone with an effort to create a suitable substrate for different types of plants in terms of accessible phosphorus content. During the experiment following plants were used between the years 2011 and 2015: Gazania rigens, Ocimum basilicum and Mentha piperita. For a control substrates following variants were used: Different types of commonly used growing substrates as the controls; peat combined with unseparated digestate in proportions of 5, 10, 15, 20, 25 % volume. In selected years dolomite limestone was also added in doses of 3, 6, 10, 15 g/l to stabilize pH. The results of the work show a positive effect of the digestate on the substrate properties as for example pH value (with possible addition of limestone for stabilization) or dry matter. Digestate appears to be a suitable source of phosphorus for plants. In terms of the above-ground biomass yield of plants reached its maximum value at the control substrate Gramoflor. From the tested substrates it was in the most cases the substrate with 10 % digestate (in two years with doses of 6 a 15 g/l). Highest percentage of dry matter reached usually the control substrates