What are hydroponics?
This is a system of growing crops where compost and soil is replaced with a water solution or substrate like rock wool.
The use of hydroponics allows more control of the root system and plant growth by controlling the amount of nutrients and water the plants (and roots) receive.
As the amount of land for growing food is reduced in the future, we will need use intensive growing systems such as hydroponics to increase food production. Edible food crops were produced hydroponically by astronauts on board the International Space Station for the first time in 2015.
Growing commercially with hydroponics
Other crops may be grown hydroponically, such as strawberries and cut flowers, for example tulips and chrysanthemums. These production systems are designed to enable the fruit or flowers to be harvested efficiently.
There are two types of hydroponics:
Plants grown in substrates such as coir, rockwool and pumice
Plants grown in a solution hydroponic system. This includes nutrient film technique (NFT) and deep water culture (DWC).
In all hydroponic growing systems the health of the root system depends on sufficient air spaces in the substrate or oxygen content of the solution.
N.B Aeroponics is a more specialised form of solution hydroponics where the roots are misted with dilute nutrient solution.
Growing using technology
Hydroponic crops are grown under cover, either in a glasshouse or polytunnel. It is possible to extend the growing season with the use of extra heat and light.
Computers are used in glasshouses or polytunnels to check how much heat, light, water and nutrients the crop requires; they continuously measure the pH solution and strength of the feed solution through electrical conductivity.
The liquid feed must contain all the key growing elements (N.P.K, plus trace elements of Fe and Mg) at the correct ratio for that specific crop to grow well. This is delivered to the plants via a drip irrigation system and samples of the feed are taken every two weeks for laboratory analysis. The picture below shows one variation of a computer system that controls the nutrients and watering.
The use of LED lighting is increasing in the horticultural world. It is possible to design a 'light recipe' providing the correct wavelength requirements for a specific crop. This provides possibilities for intensive plant and crop production in the future in spaces such as disused tunnels underground. The LED lights in this image show a mix of blue red and green. These are being used as in-canopy lights which help leaves and fruit grow and develop lower in the crop canopy.
No more pests?
Hydroponically grown crops do not suffer from soil-borne pests, diseases or viruses as no soil is involved in the growing process. However this means that hydroponic crops cannot be grown organically.
Biological control organisms are used to control pests on the crops, this is easier under glass or in a poly tunnel. The main aim to to create a natural balance between the pest and the predator, and in order to do this, the biological control is introduced then monitored on a weekly basis.