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Leaving Earth Behind – UK
The traditional method of growing crops requires three fundamental elements: light, water and soil. But another method, hydroponics, eliminates the need for soil, while enabling plants to thrive. Doing without soil means you can grow crops anywhere, as long as other conditions are kept right.
History of Hydroponics
Hydroponics comes from the Greek words ‘hydro’ meaning water, and ‘ponics’ meaning works – the water does the work of growing the plants.
Evidence of hydroponic activity dates back to ancient Greek and Egyptian times. In the 18th century, scientific discoveries led to a greater understanding of plant growth, and determined that plants need soil only for ballast, to support themselves in the ground. It is the essential nutrients that are dissolved within the soil,which enables the plants to grow.
Interest in hydroponics grew during the Second World War, as there was a high demand for vegetables in remote areas. Although activity continued through to the 1960s, techniques were not fully developed and success was limited.
However, interest in the potential of hydroponic culture was still high. In the late 1970s the advent of high-grade cheap plastics meant these materials were incorporated into simpler design systems – plastic pipes were used for the feed systems, plastic injector pumps and reservoir tanks were developed, and energy-saving polythene greenhouse covers were produced.
Both small and large hydroponic farms were established which proved that with proper management this practice could produce premium produce and be a profitable venture. Now there is a strong hydroponic market for complete plant nutrient formulas, environmental control systems and hydroponic greenhouse systems that provide the ideal growing environments.
Hydroponic Systems
In a soil-based system, vital nutrients are often washed away before the plants can absorb them. With hydroponics these nutrients are delivered directly and efficiently to the plants to encourage growth.
In a hydroponic system, soil is replaced with an inert substance such as vermiculite, perlite, clay granules, gravel, coir fibre, or cocoa bean shell, which simply supports the plant. Nutrients, mostly combinations of nitrogen, potassium and phosphate with other trace elements such as calcium, magnesium and sulphates, are dissolved in a plant feed, which is delivered as a solution directly to plant roots.
Hampshire Hydroponicum, a UK hydroponic grower, uses a closed-circuit nutrient stream, enabling the water to be re-circulated. Water is pumped into a top tank, fed by gravity through the channels, past the plant roots and into a bottom collection tank. From there it is pumped back to the top tank and then recirculated past the plant roots. This means no water is lost through evaporation and all the nutrients are taken up as the plant needs them. Instead of using electricity, the system is run on the water pressure from the main water tank. In this controlled environment the plants receive a constant and controlled supply of nutrients. This system requires much less water than is used in traditional farming.
At different stages of growth plants may require different nutrients. In the vegetative growth phase this would be a 'grow' nutrient, and in the flowering and fruiting phase this would be a 'bloom' nutrient. When the plants are young they are fed with a very diluted nutrient solution and as they progress into the flower and fruit growing stage the strength of the feed is increased to match the demands of the plant. Care must be taken not to overfeed the plants and ensure the correct pH level is maintained, generally around 6.3, to enable nutrient uptake.
Plants grow a lot faster with this method than they would in a normal soil bed. They are also healthier, making them more resistant to pests and diseases. There are no soil-borne diseases, no weeds to pull, and no soil to till, and plants can be placed very close to one another. This allows a large amount of food to be produced in a small amount of space.
There are several other hydroponic methods:
Passive The plants are placed in a growing medium that allows oxygen to reach the roots, and capillary action delivers water and nutrients to the roots. The water is regularly topped up, and the nutrient solution is occasionally replaced to keep the medium flushed with nutrient and air. It is important in passive hydroponics to wash out the system from time to time to remove salt build up, and to check the pH level.
Deep water culture The plant's roots are suspended above an aerated nutrient solution and allowed to dangle into the solution. The solution needs to be constantly aerated so oxygen can get to the roots to ensure the uptake of nutrients. The container holding the roots and aerated nutrient solution must be completely light-proof in order to prevent the growth of algae.
Wick feeding The plant draws up water by means of a wick. The wick runs from the base of the plant container down to a bottle of nutrient feed solution. The solution travels up the wick into the pot plant.
Nutrient film technique (NFT) The plants grow in a light-proof plastic tray which is gently sloping. A constant flow of nutrients is maintained along the tray, and the roots grow into dense mats, with a thin film of nutrient passing over them.
Apart from initial set-up costs the main disadvantage has traditionally been the large amounts of water and energy used. But systems which use water pressure to recirculate the water require no electricity at all. Modern greenhouses can be controlled, so suitable temperature and humidity levels are maintained. Some growers use a computerised control system to simplify this process. So the plants are grown cheaply, efficiently and in the most environmentally friendly way possible.
Further Information
Participating Organisations
Hampshire Hydroponicum
Houghton Lodge & Gardens
Stockbridge
Hampshire SO20 6LQ
UK
Tel: +44 (0)1794 388383
E-mail: mail@hydroponicum.info
Website: http://www.hydroponicum.info/
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