SOIL REHABILITATION AND EROSION CONTROL THROUGH AGROECOLOGICAL PRACTICES ON REUNION ISLAND (FRENCH OVERSEAS TERRITORY, INDIAN-OCEAN)

On the western slopes of Reunion Island, the trends in cropping system s for perfume pelargonium are causing serious erosion problems, This p aper reviews the causes of these trends, presents the consequences of this deterioration, and assesses the agro-ecological solutions by mean s of cover plants and hedging with agroforest species, Firstly, the sh ort term effects of cover plants (Lotus uliginosus, Pennisetum clandes tinum) associated with the pelargonium crop are considered. Using rain fall simulation, it is shown that such associations have immediate eff ects in controlling erosion, although runoff is not significantly redu ced, The more long-term effects of this type of cover are then compare d with pelargonium monoculture on bare soils, and with pelargonium in rotation with stable crops. The effect of hedging along plot boundarie s is also observed. Descriptions of soil profiles highlight the advant ages of plant cover, in improving soil structure and biological activi ty, Near hedges, the same tendencies are even more marked, Soil hydrau lic conductivity, measured in the various situations, confirms the com plementarity of cover plants and hedges in association. The plant cove r reduces erosion, with only a slight increase in water infiltration. At the same time, soil under hedges gives rise to very high water cond uctivity which should enable a large proportion of runoff water to be absorbed.