There is currently a lot of intertest in the use of hydroponics to grow food. It is being hailed as the way to solve the food crisis and provide cheap food in cities. The usual arguments are that redundant buildings can be used in city centres, or even old underground railway tunnels thus reducing food miles. It is being pushed as the only way forward especially by the media as it makes a good story.
I have nothing against growing food in cities and it is something that I have advocated for many years. There are many small plots of land that should be used for food production as well as flat roofs on building which make ideal growing spaces. See this from 2008 and this from 2009 and there are many more examples on the City Farmer web site
There are problems with the current push by the hydroponic industry not least of which is the claim that it is ‘organic’.
Hydroponic growing uses N-P-K fertilisers, (nitrogen, phosphorous, potassium) dissolved in water that is fed to plants. Some systems use plastic troughs through which water constantly circulates while other use an artificial substrate. They all rely on the same chemical fertilisers used in conventional farming which require huge amounts of energy to make. The mining of potash is an environmental disaster as is the continuing high level of depletion of other resources. None of this is sustainable in the long term.
To grow strong, healthy and nutritious plants requires more than just N-P-K, fertilisers. Soil contains many micro-nutrients which are essential for healthy, disease resistant plants. Hydro growers will argue that their fertilisers contain other chemicals but they can never truly mimic the complex web of nutrients available in soil.
Hydroponics uses products like rock wool, vermiculite or perlite to anchor plants roots in the early stages of growth or as a substrate for the whole life of the plant. After use these products are discarded as they cannot be reused due to fear of infection. They are products manufactured from minerals using large amounts of heat. Again, very unsustainable.
Being organic is about caring for soil which is the most valuable asset we have. That means not using artificial fertilisers or pesticides. Hydroponic growers make a lot of noise about using less pesticides but forget about the chemical fertilisers they rely on. Hydroponic growing will never be certified as organic in the UK and cannot be sold as such.
There are ways to grow real organic food in cities and it is something we should be doing. Hydroponics is not the answer although it gets a lot of news because of the high-tech novelty value of rows of plastic containers growing plants under artificial lights. The real way to grow good food is outside in soil or soil based composts.
Coming soon, a design for an autonomous, solar powered, organic vertical growing system!