Modelling agricultural carbon removal & mitigation strategies Spatial and temporal dynamics of soil, crops, and biomass utilization
Doctoral thesis, 2026
Agriculture is essential for food, feed, fibre and a wide range of materials, while being a major source of greenhouse gas (GHG) emissions, accounting for about 22 % of global emissions and 15 % of Sweden's territorial emissions. Most of these emissions are biogenic, arising from nitrogen turnover, microbial activity and livestock which makes them difficult to eliminate completely. Agriculture is therefore considered a hard-to-abate sector, where residual emissions must be balanced by carbon dioxide removal (CDR). At the same time, agricultural land holds substantial CDR potential through increased soil organic carbon (SOC) storage and the use of biochar as a soil amendment. Furthermore, the use of bio-based fuels, materials and chemicals can help reduce fossil carbon emissions while storing carbon outside the atmosphere. While there are several mitigation measures, their potential outcomes and effects depend on how and where they can be implemented, and particularly how they can be sustained in practice. This requires robust monitoring and verification of their effects, careful allocation of limited land and biomass between competing uses, and solutions that fit the operational realities of farmers.
This thesis aims to develop and apply a spatially explicit analytical framework that integrates spatial and temporal datasets to evaluate carbon removal and selected mitigation pathways in Swedish agricultural systems. The thesis consists of four papers that progress from field to national scale. Paper A establishes a scalable monitoring, reporting and verification (MRV) foundation by reconstructing field-level land use data and linking these to repeated national soil sampling campaigns. Paper B integrates farmer interest in changing farming activities with existing crop rotations to assess management measures at landscape level. Papers B and C quantify trade-offs and synergies between alternative biomass uses, including ley cultivation, biochar and green biorefinery side streams. Paper D assesses the spatial deployment of biomass-based mitigation across Sweden.
The findings of this thesis show that agricultural climate mitigation depends not only on theoretical potential, but also on where measures are implemented, how resources are allocated, and practical conditions. Taken together, the papers show that measurement, modelling and spatial analysis are interdependent parts of a credible mitigation assessment. Monitoring shows what has happened, modelling explores what could happen under different choices, and spatial analysis shows where this can be realized. Modelling and spatiotemporal analysis can therefore support decisions on where and how to implement measures, and monitoring of the implemented measures in turn shows whether they achieve their intended outcomes. By connecting these functions in one framework, this thesis provides a foundation for matching agricultural climate change mitigation to local soils, farming systems, biomass resources, infrastructure and stakeholder priorities.
This thesis aims to develop and apply a spatially explicit analytical framework that integrates spatial and temporal datasets to evaluate carbon removal and selected mitigation pathways in Swedish agricultural systems. The thesis consists of four papers that progress from field to national scale. Paper A establishes a scalable monitoring, reporting and verification (MRV) foundation by reconstructing field-level land use data and linking these to repeated national soil sampling campaigns. Paper B integrates farmer interest in changing farming activities with existing crop rotations to assess management measures at landscape level. Papers B and C quantify trade-offs and synergies between alternative biomass uses, including ley cultivation, biochar and green biorefinery side streams. Paper D assesses the spatial deployment of biomass-based mitigation across Sweden.
The findings of this thesis show that agricultural climate mitigation depends not only on theoretical potential, but also on where measures are implemented, how resources are allocated, and practical conditions. Taken together, the papers show that measurement, modelling and spatial analysis are interdependent parts of a credible mitigation assessment. Monitoring shows what has happened, modelling explores what could happen under different choices, and spatial analysis shows where this can be realized. Modelling and spatiotemporal analysis can therefore support decisions on where and how to implement measures, and monitoring of the implemented measures in turn shows whether they achieve their intended outcomes. By connecting these functions in one framework, this thesis provides a foundation for matching agricultural climate change mitigation to local soils, farming systems, biomass resources, infrastructure and stakeholder priorities.
carbon dioxide removal
agricultural biomass
soil organic carbon (SOC)
monitoring
reporting and verification (MRV)
agricultural systems
spatial analysis
Author
Andreas Rehn
Chalmers, Space, Earth and Environment, Physical Resource Theory
Agriculture sustains human societies by providing food, feed and a wide range of materials. It is also a major source of greenhouse gas emissions that contribute to climate change. Many of these emissions come from complex biological processes, such as nitrogen turnover in soils and feed digestion in livestock, which makes them difficult to eliminate completely. Agriculture can, however, also be part of the solution. This thesis explores how Swedish agriculture can contribute to climate change mitigation by reducing fossil carbon emissions and removing carbon dioxide from the atmosphere.
Many measures have been suggested for mitigating climate change in agriculture. The potentials of selected measures in the Swedish context are analyzed based on spatial computer modelling relying on comprehensive databases and insights from interaction with farmers. In terms of biomass resources, the focus is on perennial crops, cereal harvest residues and side streams from biomass conversion processes, which can be used in various ways that have different implications for long-term soil carbon storage, fossil fuel substitution, and nutrient recycling.
Turning cereal straw into biochar, which is then used as a soil amendment, can store carbon in the soil for centuries and improve soil fertility and resilience to drought. Growing perennial crops can achieve similar benefits, although the stability of soil carbon storage is lower. But dedicating land to perennials or removing residues from the fields can lower grain production or change how much carbon returns to the soil, so management choices are rarely straightforward.
By linking decades of farm administrative records with national soil monitoring data, and mapping biomass availability, transport infrastructure and farming systems across Sweden, the thesis builds a robust foundation for tracking how soil organic carbon changes over time and analyzing trade-offs and synergies between carbon dioxide removal through soil carbon management versus the use of biomass as an alternative to fossil fuels and other carbon-intensive resources. The thesis shows how the outcome of mitigation strategies depends on regional geography, the types of biobased products produced, and farmers' willingness to adopt certain measures. Ultimately, this work shows that effective climate action in agriculture requires looking at the whole system. It means aligning scientific models with regional conditions and the practical decisions of those who manage the land.
Many measures have been suggested for mitigating climate change in agriculture. The potentials of selected measures in the Swedish context are analyzed based on spatial computer modelling relying on comprehensive databases and insights from interaction with farmers. In terms of biomass resources, the focus is on perennial crops, cereal harvest residues and side streams from biomass conversion processes, which can be used in various ways that have different implications for long-term soil carbon storage, fossil fuel substitution, and nutrient recycling.
Turning cereal straw into biochar, which is then used as a soil amendment, can store carbon in the soil for centuries and improve soil fertility and resilience to drought. Growing perennial crops can achieve similar benefits, although the stability of soil carbon storage is lower. But dedicating land to perennials or removing residues from the fields can lower grain production or change how much carbon returns to the soil, so management choices are rarely straightforward.
By linking decades of farm administrative records with national soil monitoring data, and mapping biomass availability, transport infrastructure and farming systems across Sweden, the thesis builds a robust foundation for tracking how soil organic carbon changes over time and analyzing trade-offs and synergies between carbon dioxide removal through soil carbon management versus the use of biomass as an alternative to fossil fuels and other carbon-intensive resources. The thesis shows how the outcome of mitigation strategies depends on regional geography, the types of biobased products produced, and farmers' willingness to adopt certain measures. Ultimately, this work shows that effective climate action in agriculture requires looking at the whole system. It means aligning scientific models with regional conditions and the practical decisions of those who manage the land.
Driving Forces
Sustainable development
Areas of Advance
Energy
Subject Categories (SSIF 2025)
Environmental Sciences
Climate Science
DOI
10.63959/chalmers.dt/5954
ISBN
978-91-8103-497-4
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5954
Publisher
Chalmers
ED
Opponent: Thomas Prade, SLU