MSc and SIE projects

Context:

Soil organic carbon (SOC) is the largest terrestrial carbon reservoir, closely linked to atmospheric CO₂ through gas exchanges, making it crucial for climate mitigation. In (sub)alpine environments, where trees are absent and degradation rates are slow, SOC stores the majority of ecosystem carbon. However, much of this SOC exists in a labile form as particulate organic carbon (POC), which is vulnerable to rapid mineralization under favorable conditions. Understanding the turnover dynamics of SOC is key to predicting the effects of climate change on these vital carbon reservoirs. This MSc project aims to assess the SOC distribution among different soil fractions along a hydrological gradient in Swiss Alpine soils. 

Objectives:

1. Perform density fractionation of soil samples to quantify the different fractions and analyze the total carbon content in each fraction.
2. Characterize soil properties, including texture, total element composition, total nitrogen, and specific surface area.
3. Conduct statistical analysis to evaluate the relationship between the distribution of carbon in soil fractions, soil properties, and environmental conditions.

Knowledge and skills required:

• Broad interest in soil biogeochemistry.
• Good organization skills.
• Meticulous in laboratory practices.
• Reasonable proficiency with written English.
• Willingness to participate in the scientific publication process is a plus.

Working place: ALPOLE (Sion), some punctual analysis might take place in Geopolis (UNIL)

Contact: For further information, check out our project on Mechanisms of soil organic carbon stabilization in mountain soils and contact Bence Dienes for details.

Context: 

Mountain soils above the treeline hold a significant portion of ecosystem carbon, largely due to slow degradation rates in the harsh alpine environment. Additionally, carbon may be protected from microbial breakdown by binding with soil minerals, but the extent of this process remains unclear. This MSc thesis offers a unique opportunity to explore how soil minerals contribute to organic carbon stabilization across a hydrological gradient in selected field sites in the Swiss Alps.

Objectives:

1. Assess mineral-associated organic carbon (MAOC) through sequential selective dissolution of iron and aluminum oxides.
2. Characterize soil properties, including texture, total element composition, total nitrogen, and specific surface area.
3. Perform statistical analysis to determine the relationship between MAOC, soil properties, and environmental conditions.

Knowledge and skills required:

• Broad interest in soil biogeochemistry.
• Good organization skills.
• Meticulous in laboratory practices.
• Reasonable proficiency with written English.
• Willingness to participate in the scientific publication process is a plus.

Working place: ALPOLE (Sion), some punctual analysis might take place in Geopolis (UNIL)

Contact:.

For further information, check out our project on Mechanisms of soil organic carbon stabilization in mountain soils and contact Bence Dienes for details.

Context:

Preserving soil organic carbon (SOC) stocks is essential for mitigating climate change. SOC decomposition is primarily driven by microbial activity, where microbes utilize oxygen as the preferred electron acceptor during decomposition processes. Agricultural practices, particularly tillage, directly influence soil aeration by altering oxygen availability, thus potentially impacting SOC decomposition and stabilization. Despite the apparent significance of this relationship, the connections between soil aeration metrics -such as oxygen levels, pore structure, and redox potential- and SOC decomposition under various tillage practices have not been systematically evaluated in field conditions.

Goals:

This study aims to assess the impact of different tillage practices, specifically conventional and no-till, on greenhouse gas emissions (carbon dioxide, nitrous oxide, and methane) using a long-term tillage experiment at Agroscope-Changins. The project will involve the use of water retention curve techniques to evaluate pore size distribution across different tillage treatments and soil textures. Additionally, training in X-ray µCT will support the 3D reconstruction of soil pore networks, allowing for analysis of pore metrics such as connectivity and tortuosity. The results will link soil aeration metrics with greenhouse gas emissions and SOC stabilization, offering insights into how tillage practices influence SOC dynamics under field conditions.

Knowledge and skills required:

• Interest in soil biogeochemistry.
• Good organisation skills.
• Enthusiasm for field work and soil lab analyses.
• Reasonable proficiency with written English.
• Willingness to participate in the scientific publication process.

Collaboration: This project will be co-supervised by Orly Mendoza ([email protected]), Stephanie Grand ([email protected]) and Meret Aeppli ([email protected])

Working place: Géopolis (UNIL Lausanne)

Context:

Tillage intensity has been widely implicated in promoting the mineralization of soil organic carbon, consequently leading to an increase in atmospheric carbon dioxide concentrations. However, conflicting findings from a limited number of studies exist. Most of the existing research has primarily focused on aggregate turnover, with a lack of a systematic approach to assessing soil organic carbon stabilization in relation to mineralogical properties across various soil types and depths, particularly under different tillage practices.

Goals:

We propose to use existing samples and collect samples from topsoils and subsoils, which exhibit variations in soil mineralogy and are subjected to different tillage practices -namely, conventional, reduced, and non-tillage- in long-term tillage trials conducted in Switzerland, Italy, and Japan. Through the utilization of soil fractionation techniques, routine mineralogical analyses, and nanoscale methodologies, the student will investigate the impact of tillage intensity on soil mineralogy and in turn on soil organic carbon stabilization. Ultimately, we aim to establish a systematic link between soil mineral composition and properties with the stabilization of soil organic carbon.

Knowledge and skills required:

• Broad interest in soil biogeochemistry.
• Good organisation skills.
• Enthusiasm for soil sampling and soil lab analyses.
• Strong base training in mineralogy.
• Reasonable proficiency with written English.
• Willingness to participate in the scientific publication process.

Collaboration: This project will be co-supervised by Orly Mendoza ([email protected]), Stephanie Grand ([email protected]) and Meret Aeppli ([email protected])

Working place: Géopolis (UNIL Lausanne) and ALPOLE (Sion)

Context:

Agricultural systems are under pressure to produce increasing amounts of food for a growing human population while preserving, and ideally enhancing, the capacity of soils to sequester carbon and provide a habitat for biodiversity. To address these challenges, Nestlé in collaboration with SOIL is supporting regenerative agricultural practices. One such practice is the application of non-harmful, cheap organic fertilizers in combination with additives. These combinations of fertilizers and additives have shown promise in laboratory studies, but it remains unknown if these positive effects manifest themselves when fertilizers plus additives are applied under real-world conditions on agricultural farms. This MSc thesis aims to evaluate the effects of organic fertilizers combined with additives on two different farms in Switzerland. The study will involve both fieldwork and laboratory analyses.

Goals:

The objectives of this thesis are to:

1. Conduct greenhouse gas (GHG) measurements from soils on two Swiss farms.
2. Collect and analyze soil samples from both farms, characterizing key properties such as texture, elemental composition, pH, and X-ray fluorescence (XRF).
3. Assess the impact of organic fertilizers and additives on GHG emissions and soil properties, comparing the results with existing data from previous studies.

Working place: ALPOLE (Sion)

For more information, explore our project on Impact of chemical additives on soil health and greenhouse gas fluxes, and feel free to contact Camila Morales for further details.