The thesis examines the potential for sequestration of Soil Organic Carbon (SOC) in Sweden based on small-scale agriculture and horticulture. The essay is written from a perspective where climate change has reached a level where it is no longer enough to limit emissions, the earth must in addition serve as a sink for carbon dioxide and thus long-term storage of carbon (IPCC 2014). The initiative of 4 per mille (4 ‰ initiative, 4p1000.org) was initiated during the COP21 climate summit in Paris, which was seen as a step to move to concrete action in the context of agriculture in collaboration with civil society. The initiative is based on the knowledge that terrestrial systems hold far more carbon than the atmosphere, and that plants potential to facilitate carbon sequestration in soil is an underutilized potential in mitigating climate change. An additional and long term carbon storage of 0,04% annually of the already existing SOC would not only drastically mitigate climate change, but also contribute to increased food security and adaptation to climate change as an increase in SOC means an increase of Soil Organic Matter (SOM), soil health, fertility and resilience.
Literature studies support an analysis of carbon sequestration as a concept, and serves as a base from which questions related to carbon sequestration in Swedish farmland are formulated. The potential for carbon sequestration in Sweden is examined from the perspective of the 4 ‰ initiative, with a review of methods advocated within the initiative; eg. cover crops, mulch, no-till/low-till, polyculture, intercropping, crop rotation and succession, agroforestry systems and perennial crops, buffer zones, organic residue amendments and optimized grazing. Relevant methods and concepts such as biochar, conservation agriculture, regenerative agriculture and holistic management are also described. This is complemented with descriptions of four practical examples of horticulture and farming in Sweden in order to anchor the theory into practice. All practitioners have been selected on the basis that they have a conscious desire to promote carbon sequestration in soil. Rather than describing these practitioners solely from the perspective of carbon sequestration, a broader view is presented mirroring the need to address carbon farming from an angle of holistic context and agroecology.
With the support of scientific references and qualitative interviews, the study highlights the importance of; multifunctional approaches; established root biomass and ground coverage; increased net primary production (NPP) through plant available nitrogen; the potential of biochar as well as mycorrhiza for long term carbon sequestration. The study also highlights the great need for research in Swedish contexts in bringing clarity to questions around soil saturation of SOC in cases when rare methods such as agroforestry are used. Finally, the need for a more radical change within agricultural practices is highlighted as well as the need of support to practitioners who want to explore new regenerative ways of managing soils which promote carbon sequestration, food sovereignty and climate resilience.