Detailed characterization of plinthic soils in Southern Mali, Sub-Saharan Africa, as a secure basis for specific soil management and food security

Abstract

Mali and the other Sudano-Sahelian countries hold one of the lowest human development indexes due to climate, social and economic conditions that prevent food and fibre production. The growing demand for food production coupled with the lack of knowledge about the limiting attributes of soils induce soil degradation. Inadequate management of soils results in significant vulnerability for food security in Mali. This study aimed to analyze soils from Southern Mali with varying influences of plinthite, providing insights regarding specific management and restoration practices. Seven soil profiles in Southern Mali were studied. Morphological, physical, chemical and mineralogical attributes were assessed. The biggest physical limitations identified in Mali were: poor water infiltration, erosion and stoniness. Physical limitations were mostly due to cemented horizons and clay increase with depth. Main chemical limitations were acidity and low natural fertility. Low fertility is related to the advanced weathered-leached status of soils and the influence of sandstone, a nutrient-poor, quartz-rich parent material. Soils from Bandiagara II presented more acidity values and soil fertility limitations compared to those from Siani. Higher soil fertility in Siani could be related to volcanic sediments associated with sandstones of the studied region. Siani soils presented more clay increase with depth and are considered more erosion-prone in this sense. In soils from Southern Mali, specific management practices aiming to increase and preserve soil organic matter should be highlighted, such as integrated crop-livestock systems, cover plants (e.g., elephant grass) and corn-sunn hemp consortium.