Project properties

Title Enhanced wollastonite weathering: a CO2 negative liming practice? – A pot experiment
Group Soil Chemistry and Chemical Soil Quality
Project type thesis
Credits 36
Supervisor(s) Emily te Pas, dr. Mathilde Hagens
Examiner(s) prof. dr. Rob Comans
Contact info
Begin date 2021/08/30
End date
Description Liming with carbonate minerals is an often used practice in agriculture to increase soil pH, thereby improving nutrient availability and soil structure, and consequently plant production. However, carbonate weathering can be an important source of CO2 to the atmosphere. Instead, the application of crushed silicate minerals, i.e. enhanced silicate weathering, results in a chemical weathering reaction in which soil pH is increased and CO2 is consumed. The effects on Soil Organic Carbon (SOC), and especially on the labile and stable carbon pools, are however contradictory. Increasing soil pH may enhance microbial decomposition, resulting in CO2 emissions. However, improved soil structure may enhance the stability and formation of soil aggregates and organo-mineral associations, which are important for stable SOC storage. Furthermore, increased plant productivity may result in higher belowground carbon inputs by plants.

This MSc thesis project consists of a pot experiment in the greenhouse, in which soils amended with wollastonite, a silicate mineral (CaSiO3), and lime (CaCO3) will be studied. Furthermore, some pots will receive a wollastonite amendment in combination with biochar. Biochar, i.e. pyrolyzed biomass, is a soil amendment that may have important effects on SOC stabilisation mechanisms. Both clayey and sandy soils will be studied, as the effects on SOC stabilisation likely differ between soil types. You will conduct measurements on soil pH, plant production, CO2 uptake and emissions, and soil carbon stabilisation. Depending on your interests, the focus of your MSc thesis can be more on CO2 emissions and uptake, soil carbon pools and stabilisation mechanisms, plant productivity, or a combination of these aspects.

Start date of the MSc thesis is flexible, but preferably as soon as possible.

Further reading:

Amann, T., & Hartmann, J. (2019). Ideas and perspectives: Synergies from co-deployment of negative emission technologies. Biogeosciences, 16(15), 2949-2960.

Haque, F., Santos, R. M., & Chiang, Y. W. (2020). Optimizing inorganic carbon sequestration and crop yield with wollastonite soil amendment in a microplot study. Frontiers in plant science, 11, 1012.

Haque, F., Santos, R. M., Dutta, A., Thimmanagari, M., & Chiang, Y. W. (2019). Co-benefits of wollastonite weathering in agriculture: CO2 sequestration and promoted plant growth. ACS omega, 4(1), 1425-1433.

Paradelo, R., Virto, I., & Chenu, C. (2015). Net effect of liming on soil organic carbon stocks: a review. Agriculture, Ecosystems & Environment, 202, 98-107.
Used skills Literature review, proposal writing, pot experiment in the greenhouse, chemical analysis in the laboratory, statistical analysis, presentation skills, thesis writing.
Requirements Required courses for MSc thesis Soil Chemistry and Chemical Soil Quality.