UK Biochar Research Centre
Charchive Standard Biochars

MSc / BSc Module: Novel Strategies for Soil Carbon Storage

Key Staff:
Dr. Saran P. Sohi, Prof. Ondřej Mašek, Prof. David Manning


Novel Strategies for Carbon Storage in Soil (Course Codes: PGGE11212 and PGGE11214)

This is a learning module available to University of Edinburgh MSc students (and final year undergraduates). It connects our multi-disciplinary research on biochar and comparable soil carbon storage technologies to teaching programmes in the University. The module can be taken as a half (10 credit) or full (20 credit) option.

We focus on opportunities to manage soil carbon at a scale relevant to mitigation of global climate change, where the economic and policy drivers extend beyond carbon storage. The 2015 Paris Agreeement and asscoaited "four per mil" initiative on soil carbon provide a strong context.

Course content

Biochar production and use may be of special importance, with the potential to address multiple issues associated with the water–energy–food "nexus". Carbonation could provide a means to link urban ecology and carbon balance of land development. Peatland expansion has value to biodiversity and other ecosystem services delivery.

We consider these disruptive and/or transformative approaches in the way they affect soils and achieve soil carbon storage, considering other (and future) demands on land and natural resources. These technologies are at the interface of conventional soil management options and those classified by some as engineering for greenhouse gas removal (GGR).

The opportunity and challenges around the development and use of such technologies extends far beyond soil science. In our course, we consider each technology as part of a wider system, bringing in aspects of engineering as well addressing the policy and legislative / regulatory context. 

Those approaching the course from an engineering or social science angle will learn about agriculture as a system of natural but heavily manipulated processes - and how these are managed.

Soil carbon and land use background

Soils have a central role in the global carbon cycle. The exchange of carbon between the coupled plant-soil system and the atmosphere is greater than between the ocean and the atmosphere. The same amount of CO2 passes through the plant–soil system every 5–7 years as exists in the entire atmosphere. To mitigate the effects of fossil fuel combustion by removing atmospheric CO2 – the greenhouse gas removal (GGR) signalled in the Paris Agreement – working with the plant–soil system may be our best chance. Can we intervene with meaningful impact? This course explores some current options for doing so.

The amount of organic (plant-derived) carbon stored in the World’s soils is twice as large as that in the atmospheric CO2 pool. Organic carbon in only in slow transit back to the air via slow decomposition: deposited by plants and used by micro-organisms. Half of the carbon fixed in photosynthesis is returned via the soil rather than from immediate respiration by plants. This cycling of carbon is still six times greater than that arising from burning fossil fuel.

Soil is not only central to these stocks and transfers, but ubiquitous. Up to 5000 Mha of land is also under some form of agricultural management and 150 Mha in plantation forestry. One third of plant primary productivity is thought to be under some form of control through human use of land. The potential to manipulate soil for the storage of organic carbon from air is clear.

Soils also contain a vast amount of inorganic carbon. This is mainly in the form of carbonate minerals inherited from parent rock, with extremely long residence times. But carbonates can also form in soil through mineral weathering reactions. This natural process (carbonation) can be augmented by adding minerals such as olivine and plagioclase. Calcium and magnesium released in weathering react with CO2 that is elevated in soil by root and other biological activity.

Urban landscapes now account for 2% of the Earth’s surface and since 2014, more than half of people live in cities. Urban land is highly managed and manipulated – it is of especially high value. Initial measurements suggest that 1 Mt CO2 could be removed each year by optimising just 12,000 ha of urban land for carbonation. 

The extent of human management of soil, the size of the global soil carbon pool and the range of ecosystem services provided by soil - make soil an important focus for mitigation activities.


Relevant Research Areas: