Page 285 - Agriculture_Form_Three

Agriculture for Secondary Schools

Therefore, farmers can opt to feed to satiation. The use of floating feed enables
monitoring of fish during feeding. Feed should be consumed within 20 minutes of
being offered to the fish. If fish do not consume all the pellets within 20 minutes, the
quantity should be reduced.
(f) Proper storage of fish feeds
It is recommended that feeds should be stored in a cool and dry area to prevent
spoilage, mould growth and contamination. No gaps should be present in the storage
floor, walls or ceiling to prevent pests such as rodents from entering the storage.
Feedbags should be grouped according to feed type and size.

(g) Fertilisation and supplementary feeds
As an alternative to using solely commercial or farm-made feeds, supplementary
feed can be used in combination with pond fertilisation. Small fish feed on plankton
in a fertilised pond until they get larger when supplementary feeds with a lower
protein content are provided to them. This method is commonly applied to extensive
and semi-intensive systems where less than 5 fish are kept per square metre. The
purpose of fertilisation is to produce natural food and create a food chain that will
increase the productivity of the pond. Nutrients are added to ponds to stimulate
the natural production of phytoplankton, zooplankton and some bacteria that serve
as food for natural prey. This serves as food for the fish. With this practice, the
following aspects have to be adhered to.
(i) Do not over-fertilise
Adjust fertilisation rate and frequency to maintain light-green pondwater with
a 30 cm Secchi disc reading-see water quality section. If the water is green
enough, no additional fertiliser should be added.
(ii) Organic manure should be free from chemicals, antibiotics or hormones
When using chicken, cow or pig manure, make sure it comes from a source
where no hormones or antibiotics have been administered to the animals.
(iii) Prevent water exchange in fertilised ponds
Do not exchange the water in fertilised ponds or reduce the exchange rate to
the lowest level unless there is an emergency situation. If water is not kept in
the pond, the effectiveness of the fertiliser decreases.
(iv) Fertilisers should be distributed evenly across the entire pond surface once a
week
Ensure that the fertiliser is spread evenly on the entire pond surface. Dissolve
chemical fertilisers in water before applying to the pond. Never apply solid
fertilisers to the pond since they will fall to the bottom and will not be available
for the plankton.

Student’s Book Form Three
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AGRICULTURE FORM 3 9.11.2022.indd 274