A greenhouse is a farm device designed
to control relative humidity, rainfall, excessive sunlight, insects,
pests and other vagaries affecting vegetable and fruit production.
Growing crops under greenhouses has many advantages, among them are the
ability to produce huge quantities on a small piece of land and
continuous harvesting. The tomato varieties grown under greenhouses have
a shelf life of 21 days compared with 14 for those grown in the open.
Other crops planted in a greenhouse
include bell pepper, cucumber, watermelon, and pumpkin, among others.
The beauty is that a greenhouse can be located in the heart of the city
or near a market where the produce could be easily sold.
According to Dizengoff W. A. (Nigeria)
Ltd, greenhouse farming is a real sustainable source of income for small
scale farmers, and its use “provides youth employment, reduces
rural-urban migration, grows vegetables nearer to market, increases food
security in the vegetable segment, encourages transfer of knowledge and
know-how.”
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It takes a shorter period – two months –
for greenhouse-produced tomatoes to mature, while it takes a minimum of
three months with outdoor farming. Due to controlled irrigation and
temperatures, the crop sports a continuous output of flowers and fruits,
all at different stages. And one plant has a potential of up to 15
kilogrammes at first harvest, going up to 60 kilogrammes by the time it
has completed its full cycle.
The plant vines are supported inside the
greenhouse with sticks and strings, growing up to 50 metres in height.
If well looked after, the minimum plot of land under greenhouse
production can yield up to 5,000 tonnes of tomatoes per cycle.
An agronomist at Agronet, a greenhouse
farm located around new Bodija, Ibadan, said the farm had recorded 3,500
kilogrammes of tomatoes from 1000 plants. He, however, said it requires
adequate attention and commitment to do well.
Tomatoes are generally highly
susceptible to diseases, requiring heavy application of pesticides, but
under the greenhouse growing techniques, which come with basic training
on hygiene, most of common infections are easily kept at bay. Also kept
at bay are insects and other pests known to invade plants, as well as
weeds. Apart from huge savings on crop protection chemicals, which
constitute a huge part of production cost, less labour is employed in a
greenhouse, while exposure to chemical toxins associated with
application is minimised or eliminated altogether.
Success factors
Knowledge: In-depth training on all aspects of high yield intensive vegetable production by agronomists is required.
Quality inputs: Quality seeds, fertiliserand agro-chemicals from the beginning to the end are essential.
Design of greenhouse
The greenhouse (tunnel) is usually
constructed in 8m x 24m size, strong and durable tarpaulin cover to
control environmental factors: pest and disease, sunlight, rain and for
effective off-season growing, and continuous harvesting up to six
months.
Cost implication
Acquiring a greenhouse, which includes
seeds and chemicals for one cycle, a 500-litre septic tank, pipes and
holes, according to a source at Agronet, is sold for N1 million, in
addition to installation and other costs.
Yield and income potential
Dizengoff conservatively estimates yield
per season/kit to be 5,000 kilogrammes of tomatoes, done about two
times in a year. And Agronet said it sells a kilo at N400 per
kilogramme to supermarkets and groceries. Cucumber (six weeks),
watermelon and bell pepper could also be planted in the greenhouse,
especially in the dry season, to maximise price advantage.
Lessons from Israel and Kenya
Kenya has started greenhouse production
of tomatoes, raising hopes that the popular vegetable will become
available throughout the year at affordable prices. One of the
objectives of the programme in Kenya is supporting to help increase the
incomes of rural households, and the technology is borrowed from
Israel, where the country has most of its agriculture under greenhouses
due to scarcity of water and land. It is also widely practised in the
United States.
If the concept is widely embraced,
Nigeria could start enjoying year-round supply of tomatoes, which
currently get damaged during the wet seasons, pushing prices through the
roof, especially in the southern part of the country