increasing the variety and nutritional value of food available to consumers.
No other production system is as
efficient as hydroponic greenhouse
production in terms of the amount
of food that can be produced per
m2. It is an intensive growing system that allows for crops to be
planted at high densities and management practises make it possible
to attain yields far in excess of what
is possible in open field production.
Depending on the type of crop being grown, the system can also be
designed vertically, further increasing the use of space and thus food
production per m2. These vertical
systems are ideally suited to smaller
crops including lettuce, herbs and
strawberries and can even be used
in very small spaces. An important
part of the management practises
that increases yields of greenhouse
crops are the ability to apply water
and nutrients at the optimum concentrations and volumes at the correct time during the plant’s development.
Another aspect that makes greenhouse production an essential tool
in our goal of ensuring food security is its resource use efficiency.
Modern greenhouses are designed
the water transpired by the plants
and to re-use this to then fertigate
the plants. This enables food production even in areas where water
is very scarce.
A vertical system for producing
lettuce, spinach, herbs and
strawberries.
in such a way that all the water and
nutrients that are not used by the
plant can be collected and re-used
to fertigate the plants. Although
management of such a system can
be a bit more complex, it allows for
the production of crops using on
average only 25% of the water and
40% of the nutrients that would
have been used to produce the
same amount of a crop in the open
field. Some of the latest technology
even makes it possible to collect all
Food Security also means that people should have access to safe
foods. In a fully enclosed greenhouse it is a lot easier to reduce the
pest and disease pressure since it is
possible to physically limit the entry
of any insects or pathogens into the
structure. This significantly reduces
the need for chemical pest and disease management. Many greenhouse producers will then also use
biological pest and disease management practises such as predatory
insects to control some of the most
prevalent pests such as whitefly and
thrips.
Greenhouses do however not have
to be high-tech and be used only by
commercial growers to help improve food security but can also
assist in attaining community and
household food security. A greenhouse or tunnel at a school, church
or community centre has been
shown in many places in South Africa to create jobs, teach people
about the value of being able to
grow your own food and supply
them with nutritious food.
Different levels of technology can be applied when growing crops in a greenhouse.
An advanced soilless production
system where all the climatic factors are controlled.
A soilless system for tomato production in a greenhouse where
the climate is only semiregul ated.
Vegetables grown in the soil in a
passively ventilated greenhouse.