Effect of Agroforestry Trees on Chemical Properties of Vertisols of the Sahel Region of Borno State, Nigeria

Agroforestry practices involving the planting or retention of trees on croplands have been proposed as a simple solution to the restoration of soil fertility, especially in the semi arid regions. To test the validity of this proposal, a study to evaluate the contribution of 15 years old plantations of Acacia nilotica, Acacia senegal, Balanites aegyptiaca trees to soil fertility was undertaken on Borno vertisols. Soil samples were taken from the treated and control plots, these were analysed for soil pH, Organic matter, Nitrogen, phosphorus and Effective cation exchange capacity. The experimental design adopted was a Randomised Complete Block Design replicated four times. The result indicated a lowering of the soil pH under the tree covers while there was an increase in organic matter content in soils under Acacia senegal, increased total Nitrogen under Acacia nilotica and Acacia senegal. Changes in Phosphorus and effective cation exchange capacity did not show any specific pattern.Key Words: Vertisol, Agroforestry tree species, Chemical propertie