Evaluation of Agroforestry Practices and Their Contribution to Soil Fertility in Smallholder Farms in Benue State

Agroforestry systems have gained renewed attention as practical interventions for reversing soil degradation in the North Central zone of Nigeria, where continuous cropping and low input use have depleted soil organic matter. This study evaluates dominant agroforestry practices, specifically parkland systems and alley cropping, adopted by smallholder farmers in Benue State, with particular focus on their effects on soil fertility indicators. Soil samples were collected at two depths (0-15 cm and 15-30 cm) from forty farms across four local government areas, categorised by agroforestry type, tree density, and years of continuous practice. Laboratory analysis measured soil organic carbon, total nitrogen, available phosphorus, and soil pH. Questionnaire interviews with 120 farmers captured practice history and management intensity. Results indicate significantly higher organic carbon and nitrogen levels under alley cropping plots compared to sole crop controls, with Leucaena leucocephala showing the strongest positive association. Parkland systems involving Vitellaria paradoxa and Parkia biglobosa demonstrated moderate fertility benefits, particularly in phosphorus retention. Shallow soils on undulating terrain showed the least improvement. Findings suggest that targeted tree species selection and spatial arrangement are key determinants of fertility outcomes. The study recommends scaled promotion of alley cropping in extension programmes across Benue's agricultural zones, supported by farmer-to-farmer demonstration plots. Keywords: agroforestry, soil fertility, alley cropping, smallholder farming, Benue State