#7 Nelly: Phosphorous fertilisation, plant-availability and use-efficiency

Nelly is a postdoctoral researcher at the University of Copenhagen. She conducts research on organic and mineral forms of phosphorus fertiliser. She explores its plant-availability and models its fate in the soil to optimise its application.

Institute: Department of Geoscience and Natural Ressource Management – Geography

Nelly did her PhD at the University of Copenhagen, then went to Australia to do a first postdoc and now returned to Denmark to do a second postdoc.

Let’s start with her PhD research

Dissertation title: (link)

Potential for increasing phosphorus bioavailability of thermally treated sewage sludge using phosphate solubilising fungi


  • In vitro lab-experiments with different combinations of ashes derived from wastewater sludge with phosphate solubilising fungi and nutrients (carbon and nitrogen) to optimise the P-solubilisation activity from the inoculated fungi
  • Transfer of the most promising combination ash/fungus to a soil plant system under controlled and field conditions

Nellys findings:

  • Under soil-less lab-conditions P availability from wastewater ashes could be increased
  • In pot and field trials no beneficial effects from adding microbes to the soil could be detected
  • Theses results were against what was commonly found in scientific literature and her experiments could show that results can differ greatly between the lab and the ‘real world’

Papers in connection to PhD

Enhancing the phosphorus bioavailability of thermally converted sewage sludge by phosphate-solubilising fungi

Fertilising effect of sewage sludge ash inoculated with the phosphate-solubilising fungus Penicillium bilaiae under semi-field conditions

Survival and phosphate solubilisation activity of desiccated formulations of Penicillium bilaiae and Aspergillus niger influenced by water activity

Raymond NS, Müller Stöver D, Richardson AE, Nielsen HH, Stoumann Jensen L. 2019b. Biotic strategies to increase plant availability of sewage sludge ash phosphorus.  182(2): 175-186.

Use of Penicillium bilaiae to improve phosphorus bioavailability of thermally treated sewage sludge – A potential novel type biofertiliser

Review paper we talked about: Phosphate-solubilising microorganisms for improved crop productivity: a critical assessment

PhD Funding: Innovation Fund Denmark and Novozymes

Nelly’s postdoc in Australia

Title: Understanding P dynamics and bioavailability in alkaline clay soils

During her postdoctoral studies at the University of Queensland in Australia, she worked with a cropping model (APSIM) that should help make P fertilisation more efficient.

For that she used an existing agricultural systems computer model and laboratory incubations. To calibrate the model a lot of data is needed to represent P behaviour under different conditions such as weather, crop and soil typ.

Funding: GRDC (Grains Research and Development Corporation)

Papers in connection with Nelly’s work in Australia

Does the APSIM model capture soil phosphorus dynamics? A case study with Vertisols

Methods for assessing laterally-resolved distribution, speciation and bioavailability of phosphorus in soils

Nelly’s postdoc in Copenhagen

Title: Resilient crop production using innovative P sources supported by Microbial P Mobilisation (Mic-P-Mob)

Now back at the University of Copenhagen, Nelly co-teaches the course: Lab Methods in the Geosciences (NIGB21024U) and Kultur – og naturgeografi (NIGB14031U) and again conducts research on P.

In the course, students learn to classify soils into different groups, to understand their characteristics and from that to understand how they could be used in an agricultural context. She also teaches the students basic soil analysis done in the lab.

In her research she studies the relations between carbon, nitrogen and phosphorus in the soil and how these relations impact P availability to crops.

Funding: NovoNordisk (Plant Science, Agriculture and Food Biotechnology – Postdoctoral Fellowships 2021)

Some terms:

Agro-ecology: aims to align agricultural practices more with ecological processes to make agricultural more sustainable and resilient

Cation-exchange capacity: YouTube Video

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