Understanding processes determining soil carbon balances under perennial bioenergy crops CARBO-BIOCROP

Lead Research Organisation: Aberystwyth University
Department Name: IBERS


In contrast to annual food crops, evidence suggests that biofuels from perennial bioenergy crops have a positive greenhouse gas (GHG) mitigation potential. However, the magnitude of this benefit has been recently questioned, since long-term and indirect effects may considerably reduce any GHG savings generated by the cropping system. Indeed, impacts on soil C have been identified as the weak link in life-cycle analysis of net carbon-equivalent benefit presented by bioenergy. Changes in rates of nitrous oxide (N2O) and methane (CH4) emission are relevant too since they have a large GHG warming potential, but these changes are mostly unquantified for perennial bioenergy cropping systems. Although several soil carbon and trace-gas models have been developed for agricultural and conventional forest systems, these have not been parameterized and validated for transition of land-use to perennial bioenergy crops. To predict the changes in SOC that will occur one to three decades after establishing biomass crops, we need to establish: (a) differences in turnover dynamics and fluxes of carbon under key biomass crops in terms of amount, quality and placement of carbon into the soil from the plant; and (b) mechanisms to overcome short-term loss of pre-existing soil carbon during transition; (c) quantitative, process-based modeling approaches that are predictive, to explore future scenarios for optimum soil carbon management. The overarching aim of this project is to provide improved understanding of fundamental soil processes resulting in changes of soil carbon stocks and pools as a result of land conversion from arable/grassland to land-based renewables. The project focuses on impacts of land use change specifically to perennial bioenergy crops (fast growing SRC trees and grasses) where there is currently a significant knowledge gap. This project will generate new evidence to improve current understanding of how soil carbon processes, sequestration and emission, are affected by the introduction of perennial energy crops. The soil carbon balance is key to informing the debate on whether using these crops for bioenergy and biofuels will result in significant carbon savings compared to land use for food crops and the use of fossil fuels for heat, power and liquid fuels. In the long-term (beyond the life of this project), this will enable dynamic, spatially explicit modeling of GHG (C equivalents, abbreviated here as C) mitigation potential of land-based bioenergy systems across different climates and soil types of the UK. We wish to develop 'Carbon Opportunity Maps' for the UK. The work of the project will be undertaken in three workpackages dealing with data synthesis (WP1), experimental data collection (WP2) and modeling (WP3). Throughout the project we will use leverage of other resources including two flagship sites at Brattleby and Aberystwyth, where commercial-scale plantations are established and where several long-term measuring and monitoring activities are underway funded from elsewhere. Similarly, the modeling resources from within the project are extensive and funded from other sources that will be levered against the work here. They include DNDC, JULES, ROTH C and on-going modeling approaches for miscanthus and SRC. Outputs will include a new database of synthesized data for soil carbon under bioenergy crops. We will have tested and calibrated process-based models that are capable of simulating the dynamics of soil organic carbon, carbon sequestration and greenhouse gas emissions for perennial bioenergy crops in the UK. We will provide increased fundamental understanding of soil processes occurring under bioenergy cropping systems, including the role of mycorrhizal associations and the effectiveness of biochar as a potential to optimize soil carbon and plant growth. We will develop capacity for future 'carbon opportunity' mapping.


10 25 50
Description Conversion of large areas of agricultural grassland is inevitable if European and UK domestic production of biomass is to play a significant role in meeting demand. Understanding the impact of these land-use changes on soil carbon cycling and stocks depends on accurate predictions from well-parameterized models. Key considerations are cultivation disturbance and the effect of autotrophic root input stimulation on soil carbon decomposition under novel biomass crops. Our study provides partitioned parameters from the conversion of semi-improved grassland to Miscanthus bioenergy production and compares the contribution of autotrophic and heterotrophic respiration to overall ecosystem respiration of CO2 in the first and second years of establishment. Repeated measures of respiration from within and without root exclusion collars were used to produce time-series model integrations separating live root inputs from decomposition of grass residues ploughed in with cultivation of the new crop. Key findings include a greater understanding of the transition period during land use change from pasture to energy crop. At the 6 ha site we used in Aberystwyth, the carbon debt that occurred during the transition was in effect paid of between 2-3 following the transition. Moreover after this the site became a carbon sink and the results have implications for the benefits of planting energy crops in addition to fossil fuel substitution. However there will be site specific factors such as age of the grassland and existing carbon stocks which also need to be taken into account.
Exploitation Route Industry are interested in understanding the environmental impacts of land use change as it helps to de-risk investment decisions.
Sectors Agriculture, Food and Drink,Energy,Environment

Description Knowledge of the environmental impact of land use change involving transitions to energy crops is important to policymakers to ensure that there are net CO2 benefits arising from the planting of energy crops arising from both carbon mitigation from biomass, also taking into account any carbon lost and when that carbon debt is repaid. As a result of this project we have obtained a sparking impact award and used it to provide information to industry on the transition to energy crops to help them have the technical information when discussing with policymakers.
Sector Agriculture, Food and Drink,Energy,Environment
Impact Types Societal,Economic

Description Energy Land Use Modelling (ELUM)
Amount £191,135 (GBP)
Funding ID ELUM 
Organisation Energy Technologies Institute (ETI) 
Sector Public
Country United Kingdom
Start 05/2011 
End 05/2014
Description MAGLUE Measurement and Analysis of bioenergy greenhouse gases: integrating GHGs into LCAs and the UK Biomass Value Chain Modelling Environment.
Amount £993,785 (GBP)
Funding ID EP/M013200/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2015 
End 02/2018
Description Plants and Architecture
Amount £750,000 (GBP)
Organisation Government of Wales 
Sector Public
Country United Kingdom
Start 11/2014 
End 12/2018
Description Real time control of gasifiers to increase tolerance to biomass variety and reduce emissions
Amount £999,756 (GBP)
Funding ID EP/M01343X/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2015 
End 03/2018
Description BBC Wales Science Cafe: The Welsh Science Wishlist 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact An interview for BBC Radio Wales Science Cafe. The programme was ahead of the Welsh Government Elections in May 2016 and was to articulate The Welsh Science Wishlist for the incoming government. Iain Donnison gave the interview on wishes for the future environmental policy.

Science votes
The Welsh Government believes that science in Wales is world class. And on this programme we frequently trumpet the pioneering research at our universities. But is enough being done to build a strong and successful scientific community? Many in Wales are concerned that we are failing on science education and in preparing for the digital future. In this special edition of Science Café scientists reveal, for the policy makers, their wish lists. And ahead of next month's elections, the political parties outline their scientific priorities.
Year(s) Of Engagement Activity 2016
URL http://www.bbc.co.uk/programmes/b0776lxj
Description Cereals event 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Engagement with farmers and growers on the potential use of Miscanthus on farms in the UK and the delivery pipeline for seed based varieties, including on the potential environmental benefits on marginal low carbon soils. This including raising awareness of the availability of seed based Miscanthus hybrids and their significant advantage over rhizome based M. x gianteus in terms of cost of establishment, scaleability and disease susceptability.

More farmers aware of Miscanthus as an option and the improvements that are in the pipeline
Year(s) Of Engagement Activity 2012,2013,2014,2015
Description Royal Welsh Show 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Annual displays and activities based on agriculature and environmental green issues, including on the planting of energy crops, non-food use of plants, use of grass to make ethanol and plastics. Activities sparked discussion with farmers, and public of all ages

Visit to activities at Royal Welsh Show leads to subsequent requests for information and visits to IBERS in Aberystwyth.
Year(s) Of Engagement Activity 2007,2008,2009,2010,2011,2012,2013,2014