Beyond Orchard Age: Management Drives Soil–Leaf Nutrient Dynamics in Southern Ethiopian Smallholder Avocado Orchards

Avocado cultivation is a key agricultural practice in Wolaita, Southern Ethiopia, where smallholder farmers manage orchards of varying ages. Older orchards are often believed to have a more stable soil ecosystem due to the gradual buildup of organic matter, microbial communities, and nutrient cycling processes. However, their impact on soil–plant nutrient dynamics remains poorly studied. This study examines the influence of orchard age (5, 10, 15, 20, and 25 years) on soil fertility and plant nutrition across growth stages (preflowering, fruit setting, and postharvest). A total of 90 samples (45 soil and 45 leaf) were analyzed for macronutrients and micronutrients, alongside soil texture, bulk density (ρb), pH, organic carbon (OC), and cation exchange capacity (CEC). Additionally, orchard management practices and farmers’ estimated yields were surveyed to provide insights for improving soil fertility management. Orchard age did not significantly influence almost all of the measured soil fertility and leaf nutrients across growth stages. Yet, evaluation based on critical values indicated low levels of soil OC, total nitrogen (TN), phosphorus (P), magnesium (Mg), calcium (Ca), sulfur (S), and boron (B). Similarly, avocado leaf analysis revealed deficiencies in N, Ca, Mg, S, B, and copper (Cu) across different orchard ages and growth stages. Positive correlations between soil and leaf nutrient concentrations were observed for orchard age (N, P, K, Ca, Mg, S, B, and Zn) and tree stage (N, P, K, Ca, S, B, and Cu). Conversely, negative relationships were identified for Cu and Mg (age wise). Overall, uniformly inadequate soil fertility management could have resulted in lower fruit yield (55.41 kg/tree/year) compared to Ethiopia’s national average (92.24 kg/tree/year). These findings suggest that orchard age did not significantly influence soil fertility, thereby failing to meet the nutritional demands of avocado trees at various growth stages. To improve leaf nutrient concentration, enhanced soil management practices focusing on N, P, Ca, Mg, S, B, and Cu are recommended. Additionally, foliar applications of B‐ and Cu‐based nutrients should be considered. Further research is necessary for a more comprehensive understanding of soil fertility dynamics in avocado production.