Recent advances in soilless culture in Europe
Quantity and quality of water is one of the main issues in Europe. Southern countries with a warmer and drier climate are especially looking to enough quantity to increase production while north western European countries have to face the quality aspects of discharge water emitting to the environment. As a consequence both want to recirculate the nutrient solution in soilless cultivation, but facing different problems. For incoming water the sodium concentration should be as low as possible to avoid accumulation and, consequently, discharge. Discharge water contains nutrients (nitrates, phosphates) and plant protection products (PPPs) which pollute surface water realizing non-natural ecosystems in ditches and canals. The concentration of PPPs often appeared to be too high for quality surface water standards, it led to legislation to purify the discharge water by 95% in 2018. On the other hand it was already said that, as a consequence of European legislation, discharge of nitrogen should go down to almost zero in 2027. Preliminary results of emission free cultivation will be shown. System development took mainly place in crops as leafy vegetables, strawberries and chrysanthemums with roughly more than 10-15 plants m-2. Nutrient film technique (NFT) in various trough shapes, deep flow technique (DFT) with floating panels for lettuce and herbs often in combination with mechanisation and automation make a revival. Research emphasises on knowledge of the microbial flora in the recirculating water and resilience against pathogens. All to avoid expensive disinfection of the nutrient solution (more volume in recirculation). Slowly systems for outside are being developed facing other challenges (precipitation, frost), but for reason of nitrogen emission to ground and surface water. On a small scale urban farming on roofs of buildings are designed. As design mostly comes from industrial approach, economics are not always clear. Within substrates the strong position of stone wool remains, but organic waste flows are treated to be used as a sustainable substrate, partly to replace peat. One is looking to a way to use organic fertilizer, instead of inorganic ones, to come closer to certified organic farming.
van Os, E.A. (2017). Recent advances in soilless culture in Europe. Acta Hortic. 1176, 1-8
zero emission, hydroponic systems, nutrient film technique (NFT), deep flow technique (DFT), plant protection products, substrate, emission norms, disinfection