Topic background – Increasing soil carbon sequestration while lowering GHG-emissions and maintaining crop yields is one of the biggest societal and scientific challenges. Manure is commonly used as organic fertilizer and source for organic matter and nutrients in agriculture. However, current manure application often leads to increased GHG emissions as well as eutrophication of surface waters. Moreover, the effect of treated manure on the composition and functioning of soil microbiome and the subsequent implications for carbon sequestration and stabilization in soil, are not well understood. Optimization of manure processing may enable a better use of the nutrients, e.g. by adapting composition to enhance higher nutrient uptake rates. Focusing on the bioprocesses occurring during manure treatments and on the interaction between manure-associated microorganisms and soil properties bears the potential to reduce GHG emissions from the agricultural sector while contributing to the circular economy by sequestering more carbon.

Research challenges- Manure digestion and other (post- or pre-) treatments can improve the sustainability of agriculture practices by allowing increased reintroduction of carbon and nutrients in the food chain. However, the impact of such treatments on C and nutrient fluxes needs to be elucidated, especially in relation to the effect of the processed manure on C-uptake and GHG emissions in soils. Key factors to achieve more effective use of manure in agriculture are to elucidate the effect of organic inputs (and the microorganisms associated) on microbial community in relation to soil C dynamics. Insight obtained from this research will enable the development of manure treatments strategies to maximize soil functionality and fertility.

Objectives and methodology – The goal of this research project is to test and design manure treatments for agriculture use in order to achieve most optimal effects with respect to organic matter stabilization and reduction of nutrient loss and GHG emissions. The approach of this research consists in coupling bioprocesses technology and soil science. A first step will be to select and characterize manure treatments and identify suitable processes and related parameters as potential engineering targets for optimized manure treatments. Second step will be to optimize the processes via organic source addition with the aim to optimize nutrient stoichiometry. The third step will be to assess the effect of treated manure on soil properties with regards to C-uptake and GHG emission and identify the best manure treatments for the development of manure-based bio-fertilizer.

Students’ requirements: We are looking for a highly motivated biotechnologist (MSc degree) with affinity for soil microbiology. The ideal candidates should be a team player with excellent communication skills. Knowledge of complex analytical tools for microbial and/or organic matter characterization and of the basics of composting/digestion/fermentation is considered an advantage.

Keywords: Organic matter, N-emission, C-uptake, microbial processes, soil microbiota

• Academic Supervisors: Dr.Miriam van Eekert (Environmental Technology (ETE), Wageningen University) and Dr. Paul Bodelier (Microbial Ecology department Netherlands Institute of Ecology – NIOO-KNAW)

• Wetsus Supervisor: Dr.Valentina Sechi (Theme Coordinator Soil)

• University promotor: Prof. dr. ir Cees J.N. Buisman (Environmental Technology (ETE), Wageningen University)

Only applications that are complete, in English, and submitted via the application webpage before the deadline will be considered eligible.

Guidelines for applicants:  https://phdpositionswetsus.eu/guide-for-applicants/