Exploring the potential of grass feedstock from marginal land in Ireland: Does marginal mean lower yield?

Abstract

The production of biomass feedstock from marginal land has attracted much attention as a means of avoiding conflict between the production of food and fuel. Yield potentials from marginal lands have generally not been quantified although it is generally assumed that lower biomass yields can be expected from marginal lands. A three year study was conducted in Ireland in order to determine if grass yields of perennial rhizomatous grasses (cocksfoot, tall fescue, reed canary grass, festulolium) for anaerobic digestion from three marginal land sites (very wet site, very dry site, site prone to flooding) could match yields from better soils. Randomised complete block designs were established on each site in 2012 with two varieties of each grass species as treatments. Three grass harvests were taken from each site in 2013 and in 2014. There was no significant difference between yields from the control site and those from the very dry site and the site prone to flooding. Biomass yields from the very wet site were 85% of those from the control site. Highest yields were obtained from festulolium which were significantly higher than yields from perennial ryegrass. An energy analysis showed that maximising the production of grass from low lying mineral marginal grassland in Ireland could provide enough energy to meet the energy requirements of both the private car fleet and the heavy goods vehicle fleet while avoiding conflict with food production which could be concentrated on conventional land.