Does Wetland Biomass Provide an Alternative to Maize in Biogas Generation

The substantial amount of the agricultural biogas plants is now facing economical problems due to rising operational costs, which force them to quest for the cheaper alternative to silage maize. The aim of the study was to examine the biogas and methane yield of two wetland species: common reed and reed canary grass, and compare it to the biogas productivity of commonly used mixture of maize, poultry manure, and swine manure. In batch assay the methane yield of poultry manure was the highest and reached about 530 NL CH4 kg−1 VS. The methane yield of maize silage was lower and equaled to 435 NL CH4 kg−1 VS. Much lower values were received from reed canary grass and swine manure (204 and 171 NL CH4 kg−1 VS, respectively) and the lowest from common reed (148 NL CH4 kg−1 VS). Due to notably smaller biogas and specific methane yields grasses from landscaping are unlikely to wholly replace maize silage. However, they can be considered as interesting co-substrate, with methane productivity that is comparable to swine manure. Collecting grasses is relatively cheap, as it does not require fertilization and crop protection expenditure, while mowing of biomass can contribute to protection of biodiversity of wetlands and abandoned meadows.