Environmental Engineering Reference
In-Depth Information
May-September. These temporal variations in planting, like the harvesting of peren-
nials in May-August and November-December, of annual crops in June-September
and December, and of vegetables in December, are in accord with the bimodal
rainfall pattern and two intervening dry seasons. The staggered planting and
harvesting minimizes the risk of food shortage within the year.
Materials saved from a farmer's previous harvest were the most common
source of seeds and other planting materials. Other sources were:
•
market centres, including the local periodic market
•
agricultural extension agency
•
Adventist Development and Relief Agency (ADRA), which supplies grafted
mangoes in Sekesua-Osonson
•
PLEC, which supplies citrus and germinated oilpalm seeds.
Soil fertility regeneration
The quality of soils is pivotal to sustainable cropping. In the demonstration sites,
the most popular means of soil conservation or fertility regeneration is through
bush fallow or land rotation, whereby after a period of cropping lasting up to about
two years, the land is left to fallow for an average of one to four years. The fallow
period allows the soil to regenerate by resting and by the litter of naturally sprout-
ing plants, especially in long fallows. It also enhances natural floral diversity
through the regenerating vegetation. Especially the Krobo people in Sekesua-
Osonson use household refuse to enrich soils in home gardens.
Various forms of mulching are practised. They include the use of cleared weeds
and residue of harvested crops, and the
proka
system whereby the vegetation
cleared in the course of land preparation is left in place, without burning, and the
crops subsequently planted within it so that they may benefit from the moisture
conserved and humus generated by the vegetation mulch.
Other soil improvement practices include crop rotation and the use of chemical
fertilizer, which is severely constrained by poverty and the poor supply situation.
A PLEC attempt to encourage soil conservation through demonstration of the use of
stone lining to check erosion in sloping areas in Gyamfiase-Adenya and Sekesua-
Osonson met only a mixed reaction, apparently because of the arduous nature of the
work involved.
Weed and on-farm pest control
Weeds are a major problem in farms. Mainly they are controlled by weeding by
cutlass and hoe. Sometimes they are uprooted manually by hand. Subsequently
they may be left as mulch, or to sun-dry for burning. Weeds that do not dry and
burn easily may be buried.
Insect pests are often controlled by ash from burnt biomass, and occasionally
by a solution concocted by farmers from leaves and seeds of the
neem
tree,
Azadirachta indica
. Modern commercial pesticides are used sporadically,
