Physicochemical Properties and Fertility Level of the Vertisols Surface Horizons for muskuwaari [Sorghum bicolor (L.) Moench] Cultivation in the Sudano-Sahelian zone of Cameroon

Poor agricultural practices coupled with climatic aberrations have led to the degradation of vertisols intended for muskuwaari cultivation and consequently result in a drastic drop in crop yield. Faced with this situation, the knowledge of the state of their physicochemical properties and fertility level becomes a priority to develop strategies to restore their fertility. In this perpective, this work is inscribed to contribute to the knowledge of the state of the physicochemical properties of vertisols and the evaluation of the associated fertility level. To do this, 6 samples of cultivated vertisols associated with the rhizosphere were surveyed and collected in the surface horizon (0-30 cm) including, three samples in each administrative region of the North (Houla, Bangli, Pitoa) and the Far North (Dargala, Ibba, Moutourwa) respectively. Physical characterisation revealed that almost all of these vertisols have rather a silty texture with a very small proportion of the clay fraction (25.66-28.66%) compared to normal (40-80%). Chemically, acidity is spatially variable with generally low proportions (pH= 5.50-7.16) compared to normal (7-7.5). These vertisols also have very low proportions of nitrogen (0.03-0.08 %), organic carbon (0.95-1.9%), organic matter (1.63-3.39%), C/N ratio (19.45-49.14%), assimilable phosphorus (5.92-45.31 mg/kg), the sum of exchangeable cations (4.10-7.56 meq/100 g), cation exchange capacity (16.51-18.49 meq/100 g) and saturation of the exchangeable complex (23.33-43.14%) compared to normal especially for organic matter (2-4%), the sum of exchangeable cations (25-40 meq/100 g), the cation exchange capacity (20-45 meq/100 g) and the saturation of the exchangeable complex (80-100%). Therefore, the fertility level associated with these vertisols was very low with at least one limiting parameter. One fertility rehabilitation strategy for these vertisols is based on the use of inputs such as mycorrhizae and/or compost.