How to make more of Britain’s grasslands with better bioenergy production
An update from the Supergen Bioenergy Hub project – Bioenergy value chain – Whole system analysis and optimisation.
More than half of the UK’s agricultural land is grassland, around 12 million hectares (Mha), and yet this huge potential resource – for food, feed and fuel – is largely untapped in the most efficient, economical and sustainable ways.
The £1.95 million project, “Bioenergy value chain – whole systems analysis and optimisation”, brings together expertise in analysing large datasets, agritech and productivity, modelling and geographical information systems. Our four-year project has developed a framework that models different scenarios for making the most of this national asset. We look at how best to manage bioenergy and arable production while valuing the contributions of the natural environment through its ecosystem services[1].
It is led by Imperial College London, with Rothamsted Research and the University of Southampton, and forms part of the Supergen Bioenergy Challenge of the Engineering and Physical Sciences Research Council.
We used experimental evidence from across Britain to model different types of grassland, defined by the 2010 Agricultural Census for Great Britain, and assessed the benchmark production levels of these varieties, from improved (temporary or permanent) to semi-natural (rough grazing) grassland. We found that improved grasslands (5.5Mha) could provide around 52 million tonnes (Mt) of biomass if managed optimally for high productivity, but with costs in terms of nitrogen and water demands; semi-natural grassland (4.4Mha) provides only 12Mt of biomass, but provides 40% more groundwater recharge[2].
Current statistics suggest that farming has reduced nitrogen inputs since 1990 by around 60%; the downside is a yield gap of 40%. We explored scenarios that investigated the impact of a return to intensification, with productivity prioritised over environment at the national scale. We also evaluated grassland production scenarios for Britain to 2050 at the scale of 1-kilometre quadrants, using metamodels that included changes in climate. Based on the 2010 census, we found that production of biomass would rise from 64 to 72Mt on all grasslands, with productivity gains exclusively from improved grassland[3].
Our analysis highlights two conclusions. First, closing the productivity gap of 20Mt of biomass from improved grassland could provide enough biogas to meet 10% of the UK’s annual gas demand. Second, intensification of grassland in the lowlands could outweigh reversion of improved to semi-natural grassland in upland areas. Eventually, our project’s analysis framework will use these resource scenarios for grassland systems to balance the demands on food, energy and environmental ecosystem services.
If you would like more information please contact: Dr. Goetz M. Richter, Agro-ecological Modelling and System Analysis goetz.richter@rothamsted.ac.uk
