Environmental Engineering Reference
In-Depth Information
benefit of the crops. Using the definitions of agrobiodiversity terminology recog-
nized by the PLEC Biodiversity Advisory Group (BAG; Zarin, Huijin, and
Enu-Kwesi, 1999) proka is an element of management diversity. It is neither a land-
use stage nor a field type.
Proka in practice
In the proka traditional method of land preparation, the vegetation is cleared in
the dry season, December/January, and allowed to dry and commence decompos-
ition till about February/early March. The biomass is subsequently chopped down
using the cutlass to facilitate planting of crops at the onset of the rains. Planting
is done after the rains are well established. The type of land clearing is deter-
mined by the land-use stage and the field type envisaged.
Where and when is proka practised
At the PLEC sites in central Ghana, proka is practised in land-use stages com-
prising agroforests, orchards, and annual cropping. It is also practised when the
farmer is late in preparing the land to meet the onset of the rains.
Agroforest
In the agroforest land-use stage where the envisaged field type consists of a
mixture of staple crops and trees, land clearing comprises clearing of herbaceous
plants, shrubs, and small trees using the cutlass. Big trees are felled either by axe
and/or by fire. Some trees are deliberately left in situ with the density consciously
managed to permit adequate insolation for the proper growth of the crop mix to
be planted. Proka , as described above, is the main land preparation method.
In both PLEC sites, a typical agroforest consists of a field type made up ran-
domly of a planted mix of plantain, some fruits trees, and, in some cases, maize.
Subsequent land management consists of weeding with the cutlass and/or the hoe,
and leaving the vegetational debris in place to rot. In some cases, vegetables are
planted at spots where slashed residues are heaped around tree stumps or termite
mounds and allowed to rot, or are burnt (Quansah et al ., 2001).
Orchard
Proka as practised in the semi-deciduous forest zone of Ghana originated
mainly as the dominant land preparation method for establishing cocoa planta-
tions, which are examples of orchard. Land clearing for cocoa plantations is
similar to that described above for agroforest, except that the tree density for the
cocoa plantation is greater since the latter crop requires shade.
In its early establishment, the field type consists of cocoa seeded randomly at stake
and intercropped with plantain, cocoyam, and cassava, which supplement the shade
provided by the trees for the young cocoa seedlings. The landuse at the early stages
and during the growing phase may be more aptly described as agroforest
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