Growing media in soilless cultivation allow growers to apply water and nutrients more accurate (+15% growth) and to avoid soil diseases (+5/50% growth). Growing media, in combination with recirculation of drainage solution, reduce water use by about 50% and nutrient use by about 60%. For that and other reasons it is expected global growing media use will increase. A more precise estimation of the increase in demand is made, based on the expected growth of the world population, the expected increase in living standards for most people and the influence of several trends. Trends for vegetables include the need to address obesities, chronic micronutrient deficiencies and product safety. Trends for ornamentals include appreciation of natural aesthetics and ameliorating indoor climate and city climate. General trends include dealing with water scarcity, urbanisation, and more. The consequences of the possible higher demand are discussed in view of the availability of common growing media constituents like peat, coir, wood fibre, bark, compost, perlite, stone wool and tuffs as well as for less common but potentially available growing media (constituents) like Sphagnum, water and biochar. The influence of irrigation, drainage and support systems on growing media preference are discussed, as affected by trends, including recirculation of drainage solution, the use of organic fertilisers and developments in remote growing. In conclusion, the global growing media market is highly dynamic with the potential to increase four-fold between 2017 and 2050 with the highest per continent use shifting to Asia. The population increase is expected to contribute about 40%, income increase about 80% and trends about 40% for vegetables and 270% for ornamentals, totalling a market increase of 260% for vegetables and 490% for ornamentals. Growing media can contribute to a more sustainable production of vegetables and ornamentals as well as to public health and quality of life.

Use of peat and coir in horticulture is under pressure because of the negative effects on the environment. Peat harvesting releases CO2 into the atmosphere and changes the wetland ecosystem. Coir production can cause salt pollution in the country of origin as the product has a high salt level and is washed with fresh water before use as a substrate. HydraFiber, a specific wood fibre product was tested as substitute for (part of) peat and coir in professional potting soils. Wood fibre was mixed in 3 volume percentage ratios (30, 40 and 50 %v/v) with peat or coir. Nutrient content and stability were used to calculate appropriate fertiliser levels for each mixture for growth of a Begonia crop in an ebb and flood system. Addition of up to 50% v/v wood fibre to peat or coir has no negative effect on the rate of development to flowering of a 10 week crop. The ratio of weight/length of the plants is similar for all treatments. Addition of 40% and 50% v/v wood fibre to peat reduces water content by 16% v/v and increases air content by the same amount in the substrate in the range of -6 to -100 cm pressure head. Addition of wood fibre to coir has a similar effect. A lower average water content in substrate mixes of peat and wood fibre indicates it is more difficult to overirrigate but that it also requires a more precise monitoring of both, water content and nutrient status. It also requires a higher frequency of irrigation and more frequent adaptations of the nutrient level in the water supply. Using wood fibre in percentages from 30 to 50% v/v may also require an adaptation in the growing medium used for propagation plugs.

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Met financiële steun van het programma Kas als Energiebron heeft Wageningen University & Research, business unit Glastuinbouw een desk study gedaan naar de mogelijkheden koolzuurgas uit oxidatieve bioreactoren te gebruiken als koolzuurgasbron voor het bemesten van glastuinbouwgewassen. Oxidatieve bioreactoren worden sinds kort gebruikt om vloeibare plantenvoeding voor de glastuinbouw te produceren. De hierbij vrijkomende CO 2 wordt nog niet voor het gewas gebruikt. In de desk study is onderzocht of het mogelijk is een bioreactor met aangepaste input tegelijk voldoende plantenvoeding en koolzuurgas te laten producereen om te voldoen aan de vraag van een glastuinbouwgewas. Daarnaast wordt besproken wat dit betekent voor de input i.e. hoeveelheden benodigde grondstoffen en bijbehorende transportbewegingen. Tenslotte is er gekeken naar de te verwachten kwaliteit van de gasstroom en de te verwachten problemen bij het toepassen.