Soil Health in the Shadow of the Energy Transition - A Case Study on Carbon Sequestration in Agricultural Landscapes

Sammanfattning

As pressure on land-use increase due to climate change and a transition to fossil-free energy sources, there is a growing interest in the potential to combine agricultural activities with ground-mounted solar energy parks. While claiming agricultural land for energy production sparks a lot of debate, a potential compromise may lie in utilizing depleted agricultural land for solar farms, purposely managing these areas as grasslands to promote carbon sequestration as a climate mitigation and soil improvement tool during the operational phase of a solar park. This thesis will therefore investigate the potential synergies and trade-offs between such restorative land management practices and solar energy production at the planned 103-ha Kogshult Solar Park in southern Sweden, located on low-productivity agricultural land. Three existing land-use types – cropland, pasture, and fallow – were sampled and analysed to evaluate soil structure and the concentration of organic carbon and nitrogen. Further, a comprehensive analysis of previous long-term experiments on carbon sequestration in similar climate, soil and land-use conditions were compiled to assess sequestration potential. Results indicate that under proposed transitions to forage ley or sheep pasture – supported by improved management practices such as permanent vegetation cover, increased functional species diversity, inclusion of nitrogen-fixing legumes, and rotational grazing – all land-use types may achieve C sequestration during the 40-yearlong operational phase. Although the presence of solar panels will likely limit the full sequestration potential, early vegetation establishment and consistent management could support long-term gains in soil organic carbon. Preliminary estimates suggest plausible sequestration rates ranging from 0.1 to 0.4 ton C ha-1 year-1. However, the extent to which soil fertility will improve remains uncertain. Continuous monitoring and periodical sampling are essential to determine actual sequestration rates under the recommended management regime and to evaluate the compatibility between C sequestration and solar energy production at Kogshult.