Enhancing soil carbon in solar farms through active land management: a systematic review of the available evidence

Abstract

Ground-mounted solar farms are becoming common features of agricultural landscapes worldwide in the move to meet internationally agreed Net Zero targets. In addition to offering low-carbon energy, solar farms in temperate environments can be purposely managed as grasslands that enhance soil carbon uptake to maximise their climate benefits and improve soil health. However, there is little evidence to date on the ecosystem effects of land use change for solar farms, including their impact on soil carbon storage and sequestration potential through land management practices. We review the latest evidence on the associations between grassland management options commonly adopted by solar farms in temperate regions (plant diversity manipulation, mowing, grazing, and nutrient addition) and soil carbon to identify appropriate land management practices that can enhance soil carbon within solar farms managed as grasslands. Soil carbon response to land management intervention is highly variable and context-dependent, but those most likely to enhance soil carbon accrual include organic nutrient addition (e.g., cattle slurry), low-to-moderate intensity sheep grazing, and the planting of legume and plant indicator species. Plant removal and long-term (years to decades) mineral fertilisation are the most likely to result in soil carbon loss over time. These results can inform policy and industry best practice to increase ecosystem service provision within solar farms and help them deliver net environmental benefits beyond low-carbon energy. Regular monitoring and data collection (preferably using standardised methods) will be needed to ensure soil carbon gains from land management practices, especially given the microclimatic and management conditions found within solar farms.