In sub-Saharan Africa, soil fertility remains a critical challenge due to increased land demand, continuous cultivation without fallow periods, poor soil management practices, and the removal of crop residues. Thus, integrating agroforestry tree species into farming systems offers a sustainable solution by improving soil fertility, preventing erosion, and enhancing water use. Nitrogen-fixing tree species play a vital role in enhancing soil physicochemical properties through nitrogen fixation and organic matter contribution, thereby improving crop yield. This systematic review compiled 33 peer-reviewed articles on the effectiveness of agroforestry, particularly focusing on improving soil physiochemical properties and crop productivity. The articles selected for this review were published from 2014 to 2024. The review results showed that agroforestry fertilizer tree species have good potential for improving soil chemical and physical parameters. Soil bulk density, cation exchange capacity, soil organic carbon, total nitrogen, available phosphorus, and exchangeable potassium were significantly higher under the canopy of fertilized trees than open farm land. Simultaneously, studies have highlighted that crop yields are higher under tree canopies than open fields, this emphasizing the importance of tree proximity. The review underscores the potential of agroforestry in sustainable agriculture, advocating for broader implementation and research to optimize tree–crop interactions and address soil fertility issues in sub-Saharan Africa.
Wolde et al. (Tue,) studied this question.