An Ecotron experiment at Gembloux Agro-Bio Tech tests four BBFs under reference and future meteorological conditions.

An Ecotron experiment at Gembloux Agro-Bio Tech (University of Liège, Belgium) complements previous field trials carried out across Europe to evaluate the efficiency of sea2land’s bio-based fertilisers (BBFs) in broccoli cultivations under reference and predicted future meteorological conditions. The Ecotron facility in Gembloux consists of six controlled environment rooms (CERs), in which any meteorological conditions can be realistically reproduced, including the weather of the past and climate projections of the future. It is designed to simulate in a realistic way actual and future environmental conditions and allows to monitor in vivo the behaviour of the confined ecosystems, from soils to plants to the atmosphere.






In the framework of the sea2land experiment, the smoothened mean of historical climate data of the period 1981 to 2017 was chosen as a control environment that provides the optimum growing conditions for the fertilisers to reach their maximum potential. These conditions are compared to a simulated future climate of the year 2095, generated using the Alaro-0 model (Giot et al., 2016) based on the RCP (Representative Concentration Pathway) 8.5 Wm-2 scenario (IPCC, 2014). The future climate provides weather conditions where the crops will grow under increased temperature and atmospheric CO₂ concentration, while they will also have to cope with more extreme precipitations.


Four different BBFs are tested together with a commercial fertiliser and an additional unfertilised control. The BBFs originate from the Adriatic Sea (BBF1: Amino acids and peptides), the Atlantic Sea (BBF2: Protein fraction), the Cantabrian Sea (BBF3: NPK solution with amino acids) and the North Sea (BBF4: Fish sludge pellet). The BBFs are applied at normalised doses to reach 120 kg of nitrogen input per hectare for all treatments (apart the unfertilised control).  


To assess the efficiency of the different BBFs over time, several plant health and performance parameters are measured, such as: the Nitrogen Balance Index (NBI), chlorophyll fluorescence (Fv/Fm), leaf surface area and BBCH growth stages. In addition, the leaching of nitrates (NO3), a potential pollution factor, and greenhouse gas emissions (CO₂ and N₂O) are measured weekly to evaluate the environmental impact of the different BBFs. In addition, Fluorescein Diacetate (FDA) activity is measured as a proxy of total soil microbial activity for the different BBF treatments and climate scenarios over time. Once the harvesting stage is reached, above and below ground biomass are determined and crop Nitrogen Use Efficiency (NUE) is estimated. Marketable yield is quantified on the basis of the diameter of the broccoli heads. To assess post-harvest nutrient dynamics in the cropping system, spinach will be sown as a follow-up crop and the uptake of remaining N and P will be quantified, together with biomass production. Finally, two crop models are being tested: DSSAT to predict crop growth stages and yield and DNDC to predict carbon and nitrogen dynamics.



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