Open access publications in the SLU publication database

In a field trial on marginal land different ley crop blends were cultivated and harvested as biogas substrate. The objectives of this study were (a) to determine the biomass and methane yield for the different ley crop blends and (b) to analyze the variation of the methane potential determination results in order to investigate possibilities to decrease the analysis costs by an alternative sampling and sample handling strategy. A fertilized commercial ley crop bled yielded with 8.1 t DM/ha the highest biomass yield when harvested twice a year. When only harvested once a year, the fertilized commercial ley crop blend and the original vegetation resulted in the highest biomass yields. Differences in methane potential between ley crop blends were minor at the same harvest dates. However, the specific methane potential (liters methane per kg VS) increased when crops were harvested twice a year. Calculations showed that the number of analyses for methane potential determination can be reduced significantly when collective samples are used for analysis. This way, the variation within the treatment can be decreased which aids the discovery of significant differences between treatments.