6S Elaine Leung 26
Hydroponics is a method of cultivating plants in
nutrient solution, with or without the use of an artificial medium for
mechanical support. No soil is used in hydroponics culture as compared with
traditional planting methods. In some cases, the plants are supported by inert
media such as gravel, perlite, rockwool
and vermiculite.
A primary nutrient solution usually contains
potassium nitrate, calcium nitrate, potassium hydrogenphosphate and magnesium sulphate in distilled water.
A small amount of fungicide is usually added to prevent the growth of moulds in
the solution. The formula of nutrient solution varies according to the variety
of the crop, the stage of crop growth, and the parts of the crop to be harvested
as well as environmental factors including temperature, day-length and
humidity.
Now, there are a variety of hydroponics systems
currently in use in different parts of the world. They can be categorized by
the medium that the roots submerge in, or by the way
nutrient solution flows in the system. The most commonly used hydroponics
systems are the Liquid culture and aggregate culture and Open system and closed
system.
The liquid culture method is the simplest to set up
on a small scale. The roots are hanging into the solution directly. Without an
inert medium, the plant body is usually held on a piece of Styrofoam placed
over the nutrient solution. This method is suitable for short plants such as
lettuce and spinach. For taller plants such as tomatoes and cucumbers, they may
b hung loosely with strings for support. In aggregate culture, the plant roots
grow into an inert medium and are irrigated with complete nutrient solution
held in separate tank. In both methods, the solution must be aerated for
aerobic respiration of the root cells.
In an open hydroponics system, the nutrient solution
is distributed from a reservoir to the plant, and the excess solution is drained
away as waste. On the contrary, the excess solution in a closed system is
collected and reused, forming a closed loop of solution flow.
For the benefits of hyHydroponics
methods are usually practiced in association with greenhouses. The method,
although expensive, is implemented worldwide for commercial purposes because of
many reasons.
That is when we are having hydroponics,
the crops are grown under entirely controlled environment in greenhouses. The
yield of crops will increase, and the quality of crops is improved because the
factors contributing to their growth can be controlled within optimal levels.
Besides, the effects of climatic changes are
minimized in sheltered environment. Growing seasons therefore can be extended. The
problems of pests and diseases can be kept under control. And the unit cost of
crops may be reduced as a result of high planting densities, shortened growing
seasons and the use of continuous, automated production methods. The use of
water and nutrients become more efficient in closed hydroponics systems. Leaching
of nutrients is prevented and wastage as well as pollution problems are minimized.
Apart from that, farming can be conducted in areas
where the soil or the climate is not suitable for growing crops, such as the