EJP - C-arouNd
Improving soil conservation and generative practices to enhance carbon sequestration and reduce greenhouse gas emissions.
Funding: BMBF
Collaborators: Johanna Maria Zenner, Prof. Dr. Hermann Jungkunst, Dr. Klaus Schützenmeister, Dr. Jeroen Zethof, Dr. Tatiana Rittl
Website: https://ejp-c-around.my.canva.site/
Interested in a Bachelor's/Master's thesis?
Two theses are currently being offered:
1) Effect of digested and undigested manure on the susceptibility of organic carbon to decomposition
Carbon stored in soils is the largest carbon stock on earth. Common agricultural practices often lead to increased decomposition of this carbon, resulting in the release of CO₂ and CH₄ into the atmosphere. To reduce such emissions, different types of land management are being investigated to find the best practice.
As part of the C-arouNd project, we are investigating the carbon and nitrogen cycles on an organic farm in Tingvoll (Norway). Grass-clover pastures are used to grow fodder for the farm animals, with the collected manure being returned to the fields either as is or digested (after biogas production). This soil, with and without the manure collected from the farm, is placed in columns and incubated for 3 months. As part of the final work, gas samples are taken regularly during the incubation to determine the C and N losses from the columns. At the end of the experiment, the columns will be collected and the organic carbon and nitrogen content will be determined to close the carbon and nitrogen budget.
The main question we want to answer with your BSc/MSc thesis is whether digested manure releases less organic C from the soil than undigested manure.
Supervisors: Dr. Jeroen Zethof, Johanna Zenner, Dr. Klaus Schützenmeister, Prof. Dr. Hermann Jungkunst
Contact: jeroen.zethof(at)rptu.de
2) Freeze-thaw effect on the mineralization of organic matter
Subarctic soils undergo regular freeze-thaw cycles throughout the year, which have an important influence on microbial activity in soils. It is known that thawing can release relatively large amounts of CO₂ and CH₄ through increased microbial activity, which is both an important contributor to climate change and a loss of local soil fertility. It is therefore important to better understand the underlying processes and how management practices can be adapted to reduce these losses.
As part of the C-arouNd project, we are investigating the carbon and nitrogen cycles on an organic farm in Tingvoll (Norway). Grass-clover pastures are used to grow fodder for the farm animals, with the collected manure being returned to the fields either as is or digested (after biogas production). In this work, columns are created from the collected material from the farm. Part of these columns will undergo a freeze-thaw cycle and we will regularly take gas and water samples from both the freeze-thaw columns and the control columns.
The main question we want to answer in your work is whether the use of digested and/or undigested manure affects the release of C and N from the soil during freeze-thaw conditions.
Supervisors: Dr. Jeroen Zethof, Johanna Zenner, Dr. Klaus Schützenmeister, Prof. Dr. Hermann Jungkunst
Contact: jeroen.zethof(at)rptu.de
Personal
See ResearchGate:
Zethof, J.H.T., Kalbitz, K., Jungkunst, H. F. (2026).
Soil Health-What Is It Good For?
Journal of Plant Nutrition and Soil Science https://doi.org/10.1002/jpln.70046
Zethof, J.H.T., Ebbesvik, M., Løes, A.K., Pommeresche, R., Zimmermann, J.M., Rittl, T.F.
Evaluating trends in yield and soil quality over 30 years of organically managed grass-clover ley in Norway.
Organic Agriculture, 16(1), 8, 2026. https://doi.org/10.1007/s13165-025-00538-0
Müller, A., Zethof, J.H.T., Pirani, C., Vogel, C., Maccario, L., Sørensen, S.J., Smalla, K., Kalbitz, K., Babin, D.
Inoculation of wild type or EPS mutant Bacillus subtilis does not alter rhizocompetence, soil EPS, and tomato growth in the absence of stress.
Rhizosphere, 34, 101076, 2025 https://doi.org/10.1016/j.rhisph.2025.101076
Zethof, J.H.T., Julich, S., Feger, K.-H., Julich, D.
Legacy effect of 25 years reduced atmospheric sulphur deposition on spruce tree nutrition.
Journal of Plant Nutrition and Soil Science, 187(6), 834-843, 2024 https://doi.org/10.1002/jpln.202400097
Julich, D., Julich, S., Feger, K. H., Klauder, T., Zethof, J.H.T.
Effects of Past Sulfur Deposition on the Soil Microbial Biomass at Spruce Forest Sites.
Soil Systems, 8(2), 2024. https://doi.org/10.3390/soilsystems8020037
Bettermann A., Zethof J.H.T., Babin D., Cammeraat L.H., Solé-Benet A., Lázaro R., Luna L., Nesme J., Sørensen S.J., Kalbitz K., Smalla K., Vogel C.
Importance of microbial communities at the root-soil interface for extracellular polymeric substances and soil aggregation in semiarid grasslands.
Soil Biology and Biochemistry, 108301, 2021.https://doi.org/10.1016/j.soilbio.2021.108301
Baumert V.L., Forstner, S., Zethof, J.H.T., Vogel, C., Heitkötter, J., Schulz, S., Kögel-Knabner, I., Mueller, C.W.
Root-induced fungal growth triggers macroaggregation in forest subsoils.
Soil Biology and Biochemistry, 108244, 2021.https://doi.org/10.1016/j.soilbio.2021.108244
Zethof J.H.T., Bettermann A., Vogel C., Babin D., Cammeraat L.H., Solé-Benet A., Lázaro R., Luna L., Nesme J., Woche S.K., Sørensen S.J., Smalla K., Kalbitz K.
Prokaryotic community composition and extracellular polymeric substances affect soil microaggregation in carbonate containing semiarid grasslands.
Frontiers in Environmental Science, 8:51, 2020. https://doi.org/10.3389/fenvs.2020.00051
Zethof, J.H.T., Leue, M., Vogel, C., Stoner, S.W., Kalbitz, K.
Identifying and quantifying geogenic organic carbon in soils - the case of graphite.
SOIL, 5, 383-398, 2019. https://doi.org/10.5194/soil-5-383-2019
Zethof, J.H.T., Cammeraat, L.H., Nadal-Romero, E.
The enhancing effect of afforestation over secondary succession on soil quality under semiarid climate conditions.
Science of the Total Environment, 652, 1090-1101, 2019. https://doi.org/10.1016/j.scitotenv.2018.10.235
- 09/2010 - 06/2013 BSc Earth Science (physical geography) at University of Amsterdam
Thesis: "Soil Aggregation: On abandoned fields under the vegetation in a semi-arid Mediterranean environment" - 09/2013 - 08/2016 MSc Earth Science (track Geo-ecological dynamics) at University of Amsterdam
Thesis: "Long-term effects of land-use change on soil quality: Afforestation and land abandonment in semi-arid Spain" - 09/2013 - 12/2016 MSc Hydrology at Vrije Universiteit (VU) Amsterdam
Thesis: "Long-term effect of afforestation and land abandonment on the soil in semi-arid Spain: Changing Hydrological characteristics of the soil surface" - 01/2017 - 06/2021 PhD student at Institute of soil science and site ecology, Dresden University of Technology (TUD)
Doctoral dissertation topic: "The role of extracellular polymeric substances from microbes in soil aggregate stabilization in semi-arid grasslands" - 10/2021 - 09/2023 Research and teaching associate at Institute of soil science and site ecology, Dresden University of Technology (TUD), in the DFG funded project "Transition of sulphur nutrition from excessive supply to potential deficiency in spruce forest ecosystems in Central Europe"
- 11/2023 - present Postdoctoral researcher at Institute of Environmental Sciences, University of Kaiserslautern-Landau (RPTU) - campus Landau, in the BMBF funded project "EJP - C-arouNd"