10th U6+ Consortium of African Universities International Conference

Soil fertility decline is a major challenge in Hawassa Zuria District, Southern Ethiopia. Farmers practice parkland agroforestry to mitigate this problem; however, the tree species that most effectively enhance soil fertility have not yet been identified. This study therefore aimed to evaluate soil properties under three common parkland tree species such as Acacia tortilis, Croton macrostachyus, and Vachellia nilotica. Soil samples were collected at mid‑canopy (2.5 m from the trunk), canopy edge (5 m from the trunk), and open area (15 m from the trunk), and at two depths (0–0.30 m and 0.30–0.60 m). A total of 324 undisturbed and 162 composite soil samples were analyzed. Spatial distributions of soil properties were mapped using inverse distance weighting in ArcGIS (10.8). The interaction effects of tree species and radial distance on soil properties were tested with MANOVA at α 0.05, followed by Tukey’s test. Spatial maps showed the distribution of soil properties throughout the study area. In addition to spatial mapping, statistical analysis revealed the significant interaction effect of tree species and radial distance on soil properties. V. nilotica at the mid‑canopy zone exhibited the most significant improvements in soil properties along soil depths. These improvements included soil pH (6.82 in the topsoil and 6.97 in the subsoil), organic carbon (3.28% in the topsoil and 2.86% in the subsoil), total nitrogen (0.43% in the topsoil and 0.35% in the subsoil), available phosphorus (15.5 mg kg⁻¹ in the topsoil and 14.03 mg kg⁻¹ in the subsoil), and microbial biomass carbon (388.9 mg kg⁻¹ in the topsoil and 199.9 mg kg⁻¹ in the subsoil). Moreover, C. macrostachyus recorded the significantly lowest bulk density at the mid‑canopy (0.71 g cm⁻³) and canopy‑edge (0.74 g cm⁻³) positions in the topsoil, and at 0.80 g cm⁻³ (mid‑canopy) and 0.83 g cm⁻³ (canopy‑edge) in the subsoil. The significantly highest soil moisture was 15.42% in the topsoil and 28.91% in the subsoil.