We are always looking for MSc students to join our group for their theses! Please get in touch if you are interested in joining us. The following projects give you an insight into what we are working on. They are designed as full MSc projects but can be adapted to SIE semester projects. It is possible that we have other topics not listed here- feel free to reach out!
Soils store large amounts of carbon in the form of soil organic matter. The sequestration of carbon in soil mitigates climate change. Carbon sequestration is dependent on the transformation of plant inputs into soil organic matter by the soil microbial community. A technology that leverages this transformation are soil amendments containing microbial consortia that are specifically designed to enhance soil organic matter formation. This MSc thesis aims to design and test different microbial consortia in artificial soils and their influence on the formation of soil organic matter from simple carbon compounds.
The objectives of this thesis are:
- Compose artificial soil and culture bacterial strains.
- Incubate artificial soils with different combinations of bacterial strains.
- Determine changes in the properties of organic carbon using advanced analytical techniques.
For further information, check out our project on Quantifying soil organic matter formation under microbial consortia amendments and contact Emma DeFrang for details.
Mountain soils above the treeline store a majority of ecosystem carbon. Carbon accumulates in these systems mostly due to slow degradation rates in this harsh environment. Changes in temperature and precipitation patterns may shift this equilibrium, resulting either in organic matter accumulation or loss. Since both the formation and degradation of organic matter is governed by the soil microbiome, a detailed understanding of soil microbial processes is needed to project changes in soil carbon cycling in mountain soils. Soil moisture is the primary variable controlling microbial respiration pathways. The goal of this MSc thesis is to assess variations in the composition of the soil microbial community across a gradient of soil moisture conditions on selected field sites in the Swiss Alps.
The objectives of this thesis are:
- Characterizing basic soil properties such as texture, elemental composition, pH, and cation exchange capacity across a gradient of soil moisture conditions.
- Extracting DNA from soil samples and conducting qPCR to determine the abundance of bacterial and fungal genes.
- Utilizing statistical methods to analyze the correlation between variations in microbial and fungal genes, landscape positions, and soil moisture.
For further information, check out our project on Mechanisms of soil organic carbon stabilization in mountain soils and contact Kristina Bright for details.
Mountain soils above the treeline store a majority of ecosystem carbon. Carbon accumulates in these systems mostly due to slow degradation rates in this harsh environment. In addition, carbon may be protected from microbial degradation through association with soil minerals. The extent to which this mechanism drives soil carbon stabilization in this system remains unknown. This MSc thesis aims to determine the contribution of soil minerals to organic carbon stabilization on selected field sites in the Swiss Alps.
The objectives of this thesis are:
- Determine mineralogy using XRD across soils collected at various landscape positions
- Perform sequential extractions to assess the reactivity of different mineral phases
- Quantify mineral-associated organic carbon in different soil fractions
For further information, check out our project on Mechanisms of soil organic carbon stabilization in mountain soils and contact Bence Dienes for details.
Preserving soil organic carbon stocks is crucial for mitigating climate change. Soil organic carbon decomposition is primarily driven by microbes, which preferentially utilize oxygen as an electron acceptor during decomposition. Conversely, agricultural practices, such as tillage intensity, can regulate oxygen availability and the presence of anaerobic microsites, potentially impacting soil organic carbon decomposition. Surprisingly, despite its apparent significance, oxygen and anoxic microsites have received limited attention and have not been systematically linked to the stabilization of soil organic carbon stocks in soils managed under different tillage practices.
This study aims to bridge this knowledge gap by utilizing soil samples obtained from long-term tillage trials conducted in Switzerland, Italy, and Cameroon. The student will receive training in a novel approach that combines laboratory techniques for oxygen mapping and the assessment of electron donating and accepting capacity. Additionally, metrics derived from X-Ray µCT, including oxygen diffusion and pore connectivity, will be employed alongside a microbial analysis to untangle the role of oxygen and anoxic microsites in soil organic carbon mineralization. Ultimately, the insights gained from this research will be linked to carbon dioxide emissions across various tillage treatments and soil types.
Knowledge and skills required:
- Interest soil biogeochemistry and soil physics.
- Good organisation skills, ability to engage with a complex dataset.
- Enthusiasm for soil sampling and soil lab analyses.
- Reasonable proficiency with written English.
- Willingness to participate in the scientific publication process.
The student will be be co-supervised by Orly Mendoza, Meret Aeppli, and Stéphanie Grand (Université de Lausanne). They will work both at Alpole in Sion and in Géopolis at the Université de Lausanne. For further information, check out our project on Effects of tillage practices on soil carbon sequestration mechanisms.
The decomposition of organic carbon in soils has a significant impact on climate change, soil fertility, and food security. This decomposition can be influenced by physical, chemical, and biochemical mechanisms. One extensively studied phenomenon is the “priming effect” of soil organic carbon decomposition, which refers to the acceleration or deceleration of the decomposition of native soil organic carbon following the addition of fresh organic carbon inputs to the soil. Yet, there is limited information available regarding such priming effects in soils subjected to various tillage practices, especially across soils with different mineralogical compositions and climates.
This study will assess the impact of various tillage practices (conventional, reduced, non-tillage) on both added (e.g. crop residues) and native organic carbon decomposition in topsoil and subsoil with different mineralogical characteristics. The student will use soil samples from Cambisols in Switzerland, Luvisols in Italy, and Oxisols in Cameroon managed under different tillage practices. The student will employ 13C-labeled tracing techniques to distinguish between the decomposition of freshly added carbon and native soil organic carbon. Additionally, we will examine microbial factors and soil pore network structure to understand comprehensively these processes in relation to priming effects.
Knowledge and skills required:
- Interest in soil biogeochemistry.
- Good organizational skills.
- Enthusiasm for soil sampling and soil lab analyses.
- Reasonable proficiency with written English.
- Willingness to participate in the scientific publication process.
The student will be be co-supervised by Orly Mendoza, Meret Aeppli, and Stéphanie Grand (Université de Lausanne). They will work both at Alpole in Sion and in Géopolis at the Université de Lausanne. For further information, check out our project on Effects of tillage practices on soil carbon sequestration mechanisms.