Environmental Engineering Reference
In-Depth Information
paddocks constructed in the cleared area by driving wooden posts into the ground
and covering them with plastic sheets.
Farmers in the rural areas practise various forms of the outdoor system of snail
raising, which are discussed as follows. In conserved forests, enclosures are
made under the shade of single large trees or clumps of trees in moist areas,
which are the natural habitats of the snails. The enclosure is made by driving
wooden posts into the ground to create a large, circular paddock around the tree
or clump of trees. Where clumps of trees are used, the trees at the periphery of
the clump may serve as the posts. The posts are covered with plastic sheets or
nylon netting, the base of which is buried deep into the soil to prevent the snails
from crawling under. The fallen leaves from the tree create a litter bed, which
forms a suitable micro environment for the snails. Crops such as cocoyams,
banana and plantain, and other non-crop plants which form a ready source of
feed for the snails are allowed to grow freely within the fenced-off area. A source
of water supply is provided and crop stubble and harvest leftovers are served as
supplementary feed. This system closely mimics the natural environment of the
snail and allows for the high stocking rate. Such a system is in practice by
Bossman Kwapong in Gyamfiase, Adenya, a PLEC demonstration site in south-
ern Ghana. A second practice or system involves the use of pits. In this, a rec-
tangular pit, 1 m wide, 1 m deep, and of any convenient length is dug under
shade in the home garden. The base of the pit is gently sloped to facilitate
drainage during the rainy season. A layer of brick or a concrete wall is provided
above ground and fitted with a cover to keep off excessive rain and predators.
Alternately, a short nylon net cage is fitted on top of the pit to protect the snails.
The base of the pit is covered with loose soil and leaf litter. Many variations of
this system are practised, including the use of different sizes of circular pits and
different systems of confining the snails to the pits. The eggs are removed and
hatched in a different pit and the newly hatched are transferred into another pit
until they are large enough to be sent into the fattening pit. The pit system prom-
ises to provide a better security for the snails than the free-range enclosure
system. A possible disadvantage of this system is flooding under heavy rains.
Siting the pit in well-drained areas, erecting a high enough wall around it, and
providing appropriate roofing may prevent this problem.
Feeding
There is no problem with the feeding of the snails on the farm. The giant African
snail is essentially vegetarian and browses on a wide range of leaves. It also feeds
on various fruits. Almost all edible tropical drupes are acceptable to them. They
also feed on all edible vegetables, vegetable clippings, leafy vegetables, cotton
leaves, banana and plantain leaves, castor oil plant, cassava peel, and yam tubers
and leaves. In addition to this, compounded feeds are available on the market for
