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Evaluation of Changes in the Chemical Composition of Grasses as a Result of the Methane Fermentation Process and Biogas Production Efficiency
Methane fermentation, which is one of the key processes in biogas production, plays an important role in the conversion of biomass to energy. During this process, changes occur in the chemical composition of organic feedstocks, including the chemical composition of grasses. The assessment of these changes is crucial for the efficiency and productivity of biogas production. The material for this study comprised fully mature grass blades with leaves and inflorescences and was collected from extensively used meadows and pastures, as well as cultivated and set-aside areas in the Wielkopolskie Voivodeship, the communes of Białośliwie and Trzcianka, Poland. The aim of this study was to compare methane fermentation efficiency in nine grass species and identify the biomass component involved in biogas production. The results indicate that the fermentation process, as expected, changed the cellulose content. The lignin content of the grasses before fermentation varied more than the cellulose content. The content of holocellulose (sum of carbohydrate components) in the grasses ranged from 59.77 to 72.93% before fermentation. Methane fermentation significantly reduced the carbohydrate content in the grasses, with a low degree of polymerization. Grassland biomass-based biogas production is a viable alternative to conventional fossil fuels.
Natural and habitat conditions of medow communities in the Northern Polder in the "Ujście Warty" National Park
Research on natural and functional values of grassy and reed phytocenoses in the “Ujście Warty” National Park in the Northern Polder, was carried out in 2013–2019. They showed that the formation of grass communities, their richness and floristic diversity, as well as natural and agricultural values, is mainly influenced by moisture, which results from the mosaic of habitats and the intensity of use. The aim of the study was to assess the floristic diversity, natural values and utility of grass communities in leasehold complexes in the “Ujście Warty” National Park in the Northern Polder in the Natura 2000 area. One of the methods of protection and renaturation of naturally valuable meadow communities is the introduction of extensive forms of mowing and pasture use. The aim of such activities is, among others, to improve floristic diversity and prevent unfavorable transformations of protocoenoses, especially in relation to areas covered by the Natura 2000 area. Single, annual mowing during the growing season, through the implementation of agri-environmental programs, does not cause significant changes in the botanical composition of the sward, but it is conducive to restoring the most valuable natural habitats as a potential habitat for bird species endangered on a national and European scale. The distinguished communities have a diversified economic and use value of Lwu ranging from 1.1 to 7.4, and some are wastelands. The calculated floristic diversity (H’) is varied and ranges from 1.3 to 3.9, and the obtained yields are sm. range from 2.8 to 14.8 t∙ha−1 .
The Impact of the Renovation of Grassland on the Development of Segetal Weeds in Organic Farming
The intensive use or discontinuation of the use of swards can compromise biodiversity, yields, and feed quality; thus, leading to the degradation of permanent grasslands. Various methods of renovation are employed to restore the usability of degraded swards. In the years 2013–2016, a monofactorial field experiment was carried out on the Experimental Farm in Grabów (province of Mazowieckie, Poland). The experiment involved swards being reseeded after ploughing (P) and after disking with a compact harrow (H), with a non-renovated sward as the control treatment. The plots under renovation were reseeded with a lucerne–grass mixture. Both seedbed preparation methods for the renewed sward, ploughing (P) or shallow disking to a depth of 5 cm (H), were found to be effective for increasing sward yields, restricting weed growth, and reducing the number of weeds in the sward. The ploughing-based renovation method (P) had a strongly restrictive effect on biodiversity, as expressed by the H’ function value vis-à-vis the harrow method (H) and the non-renewed control (NR). Dicotyledonous species accounted for 92.3% of the weed population in the studied treatments. Of these, Taraxacum officinale, Achillea milefolium, Capsella bursa-pastoris, and Plantago maior occurred in the highest numbers.
Biogas Plant Operation: Digestate as the Valuable Product
Fertilization is an essential element in plant cultivation. Supplying the right amounts of nutrients allows plants to grow and develop. Due to the rising price of mineral fertilizers, other fertilizers and soil conditioners are growing in importance. One of these is the digestate produced in agricultural biogas plants. Due to its properties, the digestate can be used directly as a fertilizer. In this case, the effects of application can both change the soil environment and directly affect plant growth. Physical, biological, and thermal transformations can also produce products based on the digestate or its fractions, which can be successfully used for fertilizer purposes. Among other things, this paper discusses the production and use of composts, biocarbon, and/or fertilizer granules from the solid fraction of the digestate. Numerous scientific studies, including the authors’ own research in this article, indicate that digestate can be successfully used as fertilizer, both without processing and with selected methods of treatment. However, further research is needed—especially on the diversity of raw materials used for biogas production and their effects on the composition and performance of the digestate. In addition, research should continue on the processing of digestate into specific products, depending on the needs of soils and plants.