Soil productivity aspects of agri-silviculture in the West African rain forest zone

Abstract

The rain forest in West Africa is dominated by ferralitic soils, which are old, highly weathered and low in nutrient reserves and cation exchange capacity. Their fertility is mainly dependent on a delicately balanced cycle of organic matter.

Agri-silviculture as practised in this area is held to be a progressive variant of shifting cultivation in that it encourages multiple use of the land and immediate reforestation of the sites after crop harvest while providing the forest owner/cultivator with extra income from sales of poles and timbers.

Little attention has been given to the soil, which is inherently poor and further impoverished by export of portions of the meagre nutrient reserve. Drawing on various sources, this paper examines the impact of clearing and burning, cultivation and cropping and the monospecific tree fallows, on the productive potentials of these soils. It is concluded that much has still to be learnt of the restoration of soil fertility under short rotation crops, the loss of nutrients during cropping and the behaviour and response of ferralitic soils to various intensities of cropping and management methods. Some possible topics for research are suggested.