IWRA Proceedings

AbstractThe problems of the 21st century in the sudano-sahelian zone, besides the food self-sufficiency constantly postponed to the next decade, are ecological and greatly magnified by the climatic change. Because of the double failure of the struggle against the degradation of ecosystems and of the green revolution, promoted by agronomists, new modes of patrimonial management of the environment are required. Though several studies have shown the fundamental role on the agricultural zones on the hydrological balance (run off, water reserves) and on the carbon stocks of the soil, cultivated area are poorly represented in global models. The “sustainability” of the interactions between the production and the environment assumes the integration of the variability of the specific productivity of media and of the spatial distribution of resources to adapt to environmental fluctuations. To reduce the dependence of traditional food crops on environmental constrains, the management of media must rely on a large scale of innovative and traditional biophysical techniques. These techniques are based on the run-off control and the run-on agroforested management. The run-on is a part of the run-off and is defined as “a natural, complementary and simultaneous irrigation to the rainfall that has generated it in according to natural (topographical, morphological, permeability) anthropogenic (soil work) conditions”. Where the run-on infiltrates, organic carbon and nutriments that enrich the soil deposit. Organic fertilisation practices will complete the fertilisation acquired by the soil, such as BRF, mulching, animal feces, compost… Recommended techniques have been used separately with some result but their joint and rational use has been poorly studied. These techniques such as quickhedges (trees and bushes), herbeous strips, “zaï”, half-moons, earth ridges perpendicular to the slope can be implemented along the slope in combination that will be function of the morphopedological conditions. The results of these implementations on the conservation of the medium and on the soil productivity, at the field and the hillslope scale, could be used to complete and calibrate predictive models for yield (ORCHIDEE-SARRAH).