Essay: Hydroponics
Poon Kin Sang 6S 29
Hydroponic culture is one of the most exacting and intensive methods of crop
production used in agriculture today. Over the last 20 years, great advances in
hydroponic technology have been made through
extensive research and development programs in the
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 hydroponic culture as compared with traditional planting
methods. In some cases, the plants are supported by inert media such as gravel,
perlite, rockwool and
vermiculite.
The hydroponic technique was developed in the 1930s, mainly for
studying the nutritional needs of plants at that time. In these experiments,
plant roots are suspended in aerated water containing all necessary nutrients
in the right proportion specific to the plant, but with certain known or
suspected nutrients left out ( usually micronutrients
or non-essential elements ). The plants are then allowed to grow, followed by
studying the presence of abnormal symptoms that might indicate a need for the
missing element.
There are a
variety of hydroponic systems currently in use in
different parts of the world. They can be categorized
by the medium that the roots submerge in ( liquid or
aggregate culture ), or by the way nutrient solution flows in the system ( open
or 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 be 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 a separate tank. In
both methods, the solution must be aerated for aerobic respiration of the root
cells.
Hydroponic systems are further categorized as open, where after the nutrient solution has been delivered to the plant roots, it is not reused; or closed where surplus solution is recovered, replenished, and recycled. The definition of hydroponics has been confined to liquid systems only, which blurs statistical data and leads to underestimation of the extent of the technology and its economic implications. All hydroponic systems in temperate regions of the world are enclosed in greenhouse-type structures to provide temperature control, reduce evaporative water loss, and to reduce disease and pest infestations.
Hydroponics is
implemented worldwide for commercial purposes because of the following reasons.
First of all, crops are grown under entirely controlled environment in
greenhouses. The yield of crops increases, and the quality of crops is improved
as the factors contributing to their growth. Second, the effects of climatic
changes are minimized in sheltered environment. Growing seasons therefore can
be extended. Also, the problems of pests and diseases can be kept under
control. Thirdly, the unit cost of crops may be reduced as a result if high
planting densities, shortened growing seasons and the use of continuous,
automated production methods. Fourthly, farming can be conducted in areas where
the soil or the climate is not suitable for growing crops. The use of water and
nutrients become more efficient in closed hydroponic
systems too. Leaching of nutrients is prevented and wastage as well as
pollution problems are minimized. Finally, with specific treatments, hydroponically grown crops can be made more attractive and
tastier.
The principal
disadvantages of hydroponics, relative to conventional open-field agriculture,
are the high costs of capital and energy inputs, and the high degree of
management skills required for successful production. Capital costs may be
especially excessive if the structures are artificially heated and cooled. This
is why appropriate crops are limited to those with high economic value such as
tomatoes
Hydroponics is a technical
reality. Such production systems are producing horticultural crops where
field-grown fresh vegetables and ornamentals are unavailable for much of the
year. The development and use of controlled environment agriculture and
hydroponics have enhanced the economic well being of many communities
throughout the world.