This research scrutinized the effectiveness of soil-water conservation (SWC) techniques and the determinants of their adoption by smallholder farmers in Gesha District, Southwest Ethiopia. A total of 36 soil samples were collected from preserved and non-preserved plots, and a household survey was conducted with 332 randomly selected respondents. Soil physical and chemical properties were analyzed using standard laboratory techniques, while mean differences were tested through one-way ANOVA. In addition, binary logistic regression was employed to identify factors influencing the adoption of SWC practices. Results revealed that preserved plots had higher soil fertility indicators associated to non-preserved plots, including soil pH (6. 17 vs. 5. 83), organic carbon (1. 85% vs. 1. 77%), available phosphorus (10. 92 ppm vs. 9. 93 ppm), and cation exchange capacity (37. 3 vs. 30. 3 cmol (+)/kg), while bulk density was lower (0. 42–0. 69 g/cm³ vs. 1. 22 g/cm³). Adoption rates, however, remained limited to 53. 9% of households. Regression results showed that adoption was positively influenced by education, farm size, livestock ownership, land slope, and farmers’ perception of erosion, while land tenure insecurity and credit access negatively affected adoption. The findings underscore that although SWC practices significantly improve soil fertility, socio-economic and institutional constraints hinder their wider uptake. Strengthening extension services, providing tenure security, and designing targeted interventions are recommended to enhance sustainable adoption.