Abstract

In Mali, different types of gravelly soils on Cuirass were identified in association with a native vegetation including many species of tree, shrub and herbaceous. All these soils are developed by degradation of ferruginous cuirass, a material largely observed in West Africa Sudanian and Sudano-Guinean zones. Gravelly soils of Mali have a variable depth (< 10 to 95 cm depth) and gavel content (15 to 60%) and are ranged in three textural classes (silty, sandy loam and clayey loam). Their marginal status for agriculture are always justified by pedologists but they are used both for cropping and breeding (when annual rainfall ≥ 800 mm) or only for breeding (when annual rainfall < 800 mm). In manual cultivation system, many farmers prefer gravelly soils where weed control is easy. In mechanized agriculture, the gravelly soils on cuirass are used when deep soils of lowlands are not available. Agriculture use of cuirass lands favours deforestation, increase runoff, soil erosion and inundation risk at watershed scale. So, better management systems are needed and research programs must identify techniques for harvesting runoff from cuirass table and its stockage for complementary irrigation. However, the field experimentations must identify ways to improve fodder production and conservation.

Key words: Ferruginous cuirass, gravelly soils, land use, landscape degradation, West Africa contrasted climate zones.