Postdoc on the effect of organic fertilizers in soil phosphorus and carbon dynamics

Are you passionate about understanding how organic fertilization impacts soils, particularly regarding phosphorus dynamics and organic matter transformations? Do you want to contribute to cutting-edge research in soil fertility and nutrient cycling?

We are looking for a motivated and well-organized postdoc to join our team at the University of Copenhagen. The position is for 2 years.

This position is part of the projects PROCESSOR – Phosphorus recycling from complex scarcely soluble societal resources – letting the soil do the work, a collaborative research project. CRUCIAL - Closing the rural-urban nutrient cycle - Long-term field site with urban fertilizers and organic amendments, and Svensk Vatten – Studying the effects of different waste water treatment processes on the phosphorus fertilizer value of Swedish sewage sludge.

Background:

Further information on the Department is linked at https://www.science.ku.dk/english/about-the-faculty/organisation/ . Inquiries about the position can be made to Jakob Magid (jma@plen.ku.dk).

The position is open from 1 November 2025 or as soon as possible thereafter.

The University wishes our staff to reflect on the diversity of society and thus welcomes applications from all qualified candidates regardless of personal background.

Qualifications

Recovering and reusing phosphorus (P) from societal and agricultural waste streams—such as sewage sludge, meat and bone meal, and biogas residues—is key to achieving a circular, green economy. However, the fate of phosphorus in soils receiving these amendments remains insufficiently understood.

A key aspect of this postdoc position will be to study P in various organic materials, with a particular emphasis on sewage sludges and derivatives such as sludge biochar, and to investigate the processes governing the transformation of sludge-derived P into plant-available forms in soil.  Additionally, the project will explore the effect that different sludge treatment strategies (pyrolisis, alkalinization, etc), have on the fertilizer value of these materials. This will be carried out in the context of the Svenks Vatten and PROCESSOR projects.

Beyond phosphorus, societal wastes and organic fertilizers are also major sources of carbon and organic matter (OM). However, the composition, recalcitrance, and speciation of OM in these materials vary, influencing the stability and transformation of soil organic matter (SOM) fractions in the soils receiving the different fertilizers. Organic matter plays a critical role in phosphorus stabilization, mobility, and bioavailability, yet the interactions between phosphorus and size- and density-based SOM fractions—including particulate organic matter (POM), mineral-associated organic matter (MAOM), and free vs. occluded light fractions—remain poorly understood.

Another key aspect of this position is to develop and apply methods for studying SOM fractions (size- and density-based) in local long-term field experiments. These studies will provide insights into how organic fertilizers and societal wastes influence SOM composition and dynamics over time, ultimately improving our understanding of their role in soil fertility and carbon sequestration. This will be carried out within the framework of the CRUCIAL long-term field experiment.

The candidate should possess the following qualifications

• Ph.D. in soil science or a related field (e.g., environmental science, agronomy, or geochemistry)
• Background in environmental chemistry is desirable
• Strong understanding of phosphorus geochemistry and biogeochemistry
• Practical experience in characterizing phosphorus in organic fertilizers and soils using advanced analytical methodologies
• Experience with isotopic techniques (e.g., ³³P labeling) for studying phosphorus dynamics in organic fertilizers and soils
• Hands-on experience with wet chemical analyses for phosphorus in soils and residues
• Field and laboratory experience in soil sampling, handling, and routine soil fertility analyses
• Practical expertise in soil organic matter fractionation, particularly size- and density-based methods
• Strong interpersonal skills and ability to work in a collaborative research environment
• Excellent scientific writing and communication skills in English

Terms of employment

The position is covered by the Memorandum on Job Structure for Academic Staff.

Terms of appointment and payment accord to the agreement between the Ministry of Finance and The Danish Confederation of Professional Associations on Academics in the State.

The application, in English, must be submitted electronically by clicking APPLY NOW below.

Please include

• Curriculum vitae
• Diplomas (Master and PhD degree or equivalent)
• Research plan – description of current and future research plans
• Complete publication list
• Separate reprints particularly relevant papers.

The deadline for applications is 1 June 2025, 23:59 GMT +1.

After the expiry of the deadline for applications, the authorized recruitment manager selects applicants for assessment on the advice of the Interview Committee.

You can read about the recruitment process at https://employment.ku.dk/faculty/recruitment-process/ .

Interviews will be held from mid-August – September 2025.