7.6 Organic residues engineering to enhance soil organic matter and related ecosystem services

The slow decline of organic matter in many European soils is one of the biggest environmental threats. Organic matter in soils is essential as it affects water quality and water holding capacity, soil fertility and therefore food production, and furthermore the climate through CO2 sequestration and carbon storage. As such it plays a vital role in the provisioning of many ecosystem services. Soil organic matter affects the biological, chemical and physical properties of the soil and therefore it is a key component in maintain soil functionality and productivity. Treatments of organic (residual) streams such as sewage sludge, animal manures and agricultural plant residues, through e.g. composting, anaerobic digestion and fermentation, prior to land application is widely applied in agriculture to improve soil structure and fertility. However, the biochemical composition of the organic matter resulting from these treatments and its short and long term effects on soil structure and on its biochemical composition is still not well understood. This project aims on the optimal treatment of organic residues that can improve soil organic matter. Composting, fermentation and digestion, will be used to compare the influence of these treatments and their products on the soil characteristics like redox condition, the ratio of stable/unstable organic compounds and microbial ecosystem.

Research challenge
The goal of this research project is to test and design residue (pre)treatments to apply in agriculture in order to achieve most optimal effects with respect to soil organic matter. This project will test the long and short term effects of organic waste streams treatment application on soil chemical properties combining water treatment technologies with soil chemistry and microbiology.

Key questions are:
· What are the resulting chemical and microbiological properties of residues after treatment and how do they relate to the technology applied and the receiving soil?
· What is the effect of treatment of organic waste streams (e.g. composting, anaerobic digestion, Bokashi treatment) on organic matter content in soils and its biochemical composition?
· What are the key chemical and biological parameters influencing soil processes and related ecosystem service in relation to organic matter?
· How can organic (residual) streams be technologically manipulated to fit the ecosystem services that soil provides?

We are looking for a highly motivated environmental (bio)technologist with a strong interest for (soil)microbiology and organic chemistry.
The ideal candidates should be a team player with excellent communication skills.
Knowledge of complex analytical tools for organic matter and/or microbial characterization and of the basics of composting/digestion/fermentation is considered an advantage.

For this project Wetsus has started a top level consortium of soil and water scientists and six companies. The project will therefore benefit from the interdisciplinary interaction between expertise on water waste engineering and soil biochemistry.
The research project is part of the Wetsus research theme Soil.
The following companies are part of the theme:
· Agriton (
· Mulder Agro (
· Vereniging Afvalbedrijven (Dutch Waste Management Association) (
· Wetterskip Fryslan (
· Oosterhof Holman (
· Waterschap Zuiderzeeland (

Promotor: Cees Buisman (Wageningen University, Environmental Technology).
Co-promotors: Miriam van Eekert (Wageningen University, Environmental Technology)
Dr. Paul Bodelier (NIOO-KNAW)
Wetsus supervisors: Dr. Valentina Sechi

For more information contact dr. Valentina Sechi (

Please do NOT send your CV directly to this email address. Only complete applications sent via the website will be evaluated (How to Apply).

Wetsus, Leeuwarden, the Netherlands

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