The role of parkland agroforestry tree species for soil physicochemical properties and crop productivity in Hirna and Kersa, Eastern Ethiopia

Scattered parkland agroforestry trees play an important role in sustaining soil fertility and crop productivity in smallholder farming systems, yet quantitative evidence from eastern Ethiopia remains limited. This study evaluated the effects of Acacia albida, Cordia africana, and Croton macrostachyus on selected soil physicochemical properties and crop productivity in Hirna and Kersa using a factorial field experiment with soil sampling across different distances from tree trunks and soil depths. Most soil properties varied significantly with tree species, sampling distance, and soil depth ( p < 0.01). Compared with adjacent open fields, soils beneath tree canopies had higher soil moisture, organic carbon (OC), total nitrogen (TN), available phosphorus (Av. P), cation exchange capacity (CEC), and exchangeable base cations, while bulk density (BD) was lower. These improvements were greatest near the tree trunk and declined with increasing distance and soil depth. Crop grain and biomass yields were also generally higher beneath tree canopies, demonstrating positive tree-crop interactions. Among the evaluated species, Croton macrostachyus showed the greatest overall potential for improving soil fertility. These findings demonstrate that conserving and integrating indigenous parkland agroforestry trees into smallholder farming systems can enhance soil quality, improve crop productivity, and contribute to sustainable agricultural land management in eastern Ethiopia.