Environmental Engineering Reference
In-Depth Information
compared to the other non-cereal starchy staples. As such, many rural households
in many yam-growing areas in southern Ghana, especially the forest -savanna
transitional areas, maintain a rich array of yam for their year-round sustenance
and income generation. To ensure the availability of and maintain the diversity of
yams, the farmers have evolved very effective traditional production and man-
agement practices. The bush yam (
D. praehensilis
), for instance, is sometimes
grown in one spot for several decades and managed as a perennial crop.
This chapter discusses the distribution of yams in the different land-use types,
indigenous agronomic practices adopted by the peasant farmers, and the strategies
for conservation and maintenance of diversity for food security with reference to
PLEC demonstration sites in southern Ghana (Map B).
The diversity of yams
Yams cultivated in southern Ghana belong to six major species. Each species is
represented by many land varieties, some with several strains. Some species, for
instance white yams (
D. rotundata
), are used in the preparation of a wide range
of dishes, while others, such as trifoliate yams, have limited use.
The types of yams grown by farmers are determined by dietary preferences, the
requirements for the preparation of specific dishes for customary, religious, and
other celebrations, and the market value. The white yam is used more extensively
in customary rites and celebrations, while the water yam enjoys the greatest
longevity with a consequent high market value during the lean season. Other
factors that come into play in the choice of yam cultivars on farmers' holdings
include palatability. The Akyem/Akim people reportedly better appreciate the
trifoliate yam than the Krobo people.
Another basic determinant is the availability of planting material. The major
yam planting material is the edible tuber. This places a severe restriction on the
availability of planting material. The problem is further compounded by the fact
that a significant proportion of the less commercially important yam varieties are
heirloom varieties, with restricted distribution.
Agronomic characteristics such as ease of cultivation and conservation,
amenability of the variety to management as a perennial, and shelf life of har-
vested tubers are also considered by farmers in selecting the varieties to cultivate.
In a few instances, the driving force is simply an interest in maintaining heirloom
varieties for posterity.
Water yams (D. alata)
The most commonly cultivated yams in southern Ghana are the water yams. Water
yam is a vigorous-growing yam with relatively large thick leaves. It is distinguished
