Urban agriculture

The C-RAU (Centre de Recherches en Agriculture Urbaine), founded at Gembloux Agro-Bio Tech ULiège in 2011 by Prof. Haïssam Jijakli, develops expertise in urban agriculture and in the reclamation of urban and peri-urban areas.

At the heart of the WASABI platform, these urban agriculture projects, allow the study of:

Rooftop greenhouses

By installing greenhouses on the flat roofs of buildings, it is possible to reduce our CO2 emissions, while at the same time using the heat loss from the buildings to heat these greenhouses.  In Gembloux − with the SERR’URE-project (SERRe URbaine basse Energie) − the roof of the TERRA research centre has been home to this type of innovative production system since the summer of 2021. The cultural, architectural, economic and energy aspects are being considered by professionals with complementary expertise.  Innovative and cross-sectoral, this project (known as "GROOF", a contraction of "Greenhouses to Reduce CO2 on roOFs") rethinks both energy sharing and local food production.  Funded by Interreg North-West-Europe, GROOF started in 2017.  In Belgium, the University of Liege (via the C-RAU and the Smart City Institute HEC Liege), Groupe One and the Eco Construction Cluster are partners in this project.  At the European level, GROOF has been developed with eleven partners (public and private) in Luxembourg, France, Belgium, Germany and Spain. 

Some Figures 

  • 30% of energy is lost through a building’s roof on average
  • 13% of energy was saved on the TERRA roof compared to a traditional greenhouse, simply by optimising the design of the greenhouse
  • 11 partners for this project at European level
  • 9 million euro budget, including just under 1 million for the C-RAU
  • 10 projects supported by the end of 2021 across North West Europe for 1 year, with more to come
  • 4 pilot greenhouses on the roofs of the project partners, including one of 200 m2 on the roof of the TERRA research centre


Among other advantages, this cultivation technique makes vegetables and animal protein available in one place, in a circular economy mode:  water enriched by fish feces is used to feed plants; water purified by the plants can be returned to the fish water. Compared to conventional farming methods, aquaponics also has the merit of using less water and... no synthetic fertilisers, pesticides or antibiotics.  Aquaponics is also an "all-terrain" production technique: cultivation is possible in regions where open-ground horticulture is unlikely (polluted soils, arid regions or urban environments). This type of production system studied at the C-RAU is already spreading beyond our borders: many theses in international partner universities deal with these techniques, and several projects are being set up (aquaponics in Benin, bioponics in Congo and in the Sahara desert).      

To master the potential of this cultivation technique, two aquaponic systems have been developed and are being studied at the C-RAU, at Gembloux Agro-Bio Tech ULiège: the PAFF Box and SAPRISTI.

  • The PAFF Box (literally "Plant And Fish Farming Box") was the C-RAU's first step into aquaponics. Built in 2013, this compact and experimental aquaponics system has led to some great advances in subsequent, larger research projects. On the equivalent of 2 parking spaces, we study production in the city or on any type of non-exploitable soil. This prototype consists of a maritime container topped by a light-weight greenhouse. The bottom is occupied by fish and the top by hydroponic beds. The occupants live together in harmony: the water from the fish is pumped to the plants without external modifications and then returned to the fish. The PAFF Box allows the performance of plant and animal production in aquaponics to be studied. Water quality, nutrients released by the fish and their flow are measured and monitored over the long term.
  • SAPRISTI (acronym for System Aquaponics and Pilot for Research and Innovation in Science and for Transfer to Industry) is a modular aquaponics system that allows research to be carried out, while being large enough in scale to represent an industrial pilot system. It was developed through a FEAMP (Fonds Européen pour les Affaires Maritimes et la Pêche) In a few words: large fish breeding ponds and a greenhouse exist in a circular economy according to the principle of aquaponics. Since 2018, within the framework of the Smart Aquaponics project, some fifteen organisations with complementary expertise intend to reproduce the different types of professional aquaponics systems in this way, this for an ever broader audience. Various tools are being developed with the support of Interreg France-Wallonie-Vlaanderen, the Walloon Region, the Provinces of West and East Flanders and the C-RAU, which is coordinating the project. Among these tools: an interactive application which introduces its users to the reality of aquaponics:  Smart Aquaponics, the eponym of the project. This time, it is aquaponics 2.0, allowing the simulation, monitoring and study of recirculated aquaponics. This app makes aquaponics - still little known and little taught - accessible to individuals as well as to the hospitality sector, companies, schools, associations, etc.  

Some Figures 

For the PAFF Box:

  • 3 theses and a dozen dissertations and internships
  • 2 fish tanks (tilapia)
  • 800 l of water from a fish breeding pond with 10 m2 of cultures
  • 2800 l of water circulating in the whole system, with only 3% daily renewal
  • 100 adult fish reared on average
  • 4 hydroponic beds (with lettuce, basil, chard, aromatic herbs and cucumbers)


  • 8 effective aquaponics systems
  • 70 m² of available greenhouse crops linked to 3 fish rearing systems of 5 m³ each (SAPRISTI infrastructure)
  • 300,000 euro budget for the C-RAU

For Smart Aquaponics:

  • 13 partners associated with Gembloux Agro-Bio Tech ULiège
  • 2,000,000 euro of which around 500,000 euro is for the C-RAU

Market garden plots (The TERRA-Terre garden)

Is mound cultivation permaculture really adapted to the cultivation of vegetables? Is sheep wool mulching effective? Is it possible to use waste produced on the Gembloux Agro-Bio Tech ULiège faculty site to fertilise vegetables? These are some of the questions that Dr Caroline De Clerck (coordinator of scientific experiments and projects carried out on the plots) and her team are trying to answer under the leadership of Prof. Haïssam Jijakli. The results of this research will be made available to scientists from various backgrounds and disciplines. 

At Gembloux Agro-Bio Tech ULiège, the market garden plots are spread over a total area of 5,700 m2, divided into 3 parts. The different cultivation techniques applicable in urban and peri-urban areas are studied. These are: mound farming, market garden agroforestry (combination of vegetables and fruit trees) and SPIN farming (small plot intensive farming).  

A fourth part, a community vegetable garden, is intended to accommodate students and employees of the faculty, as well as citizens and schoolchildren from Grembloux wishing to cultivate a small piece of land.  It is also a space for meetings, including intergenerational ones, all within a natural environment rich in biodiversity.

Some Figures 

  • Zero pesticides
  • 750 kg of courgettes produced in 2020
  • About thirty species of vegetables
  • 1 researcher, 1 market gardening technician and 1 market gardening worker
  • 5,700 m2 of market gardening plots divided into 3 themes (permaculture, market gardening agroforestry, SPIN farming)
  • 1 cultivation mound means: 45 wheelbarrows of soil, 15 km of walking with a wheelbarrow and 3 tons of soil moved

Plant molecules of interest

Although a little on the fringe of urban agriculture, the OptiBiomasse project container has found its place on the WASABI site, a stone's throw from the aquaponics projects and the market garden plots.  In this integrated plant factory concept, hemp, euphorbia and artemisia are grown to deliver molecules of interest. This time we are talking about nutrition, but also cosmetics and health. These soil-less crops should also contribute to the revalorisation of industrial wastelands, waste energy sites and other environments where cultivation is generally considered unlikely. This will make a local supply chain more sustainable, activating the development of jobs in a professional sector with high added value.    

The project requires the implementation of advanced technologies (controlled environment vertical culture chambers, robotic phenotyping system, analytical chain of plant metabolic activity, in order to study and optimise the natural synthesis pathways of the sought molecules). 

OptiBiomasse is part of the Tropical Plant Factory project portfolio, financed by the En Mieux 2017-2020 programme (ERDF-Walloon) and supported by the VERDIR programme (ULiège). 

Some Figures 

  • about 10 employees on site
  • 2 containers dedicated to soil-less culture
  • one 6-axes robot and 2 hyperspectral caméras
  • 70 m2 of indoor vertical growing area
  • 576 m2 of outdoor culture area, phenotyping platform, molecular biology platform
  • 200 m2 of vertical hydroponic plant production
  • 1900 m2 of hemp cultivation in the field
  • 5500 plants grown in hydroponics
  • 120 kg of fresh plant biomass derived from all the species studied
  • 1050 gr of dried female hemp inflorescence produced indoors
  • 80 m2 of indoor hemp cultivation
  • 1440 data collected per 24 hours for 16 variables and per container (2 in number). This represents 46,080 environmental data collected per day
  • 4TB of imaging data processed per camera/day

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