Soil erosion is a global problem, especially severe in African countries like Ethiopia, causing land degradation and economic losses. Soil conservation and amendment practices are crucial for reducing erosion. Therefore, this study examines the effects of different soil amendments on runoff, soil loss, and soil water infiltration in disturbed and undisturbed cambisol in Laguna watershed. The experiment was conducted using a rainfall simulator found at Zenzelema campus of Bahir Dar University. After air-drying the soil sample, filled the wood try box and prepared undisturbed soil by compact for 2 month and 18 days using concrete roller approximately like the field conditions. On the experimental soil sample, equivalent rates of 2 t/ha, 40kg/ha, 2 t/ha, and 2.5 t/ha of mulch, polyacrylamide (PAM), lime, and biochar were applied to the soil, respectively. The box packed with soil was subjected to rain intensity and raindrop size of 11 mm/hr. and 2 mm, respectively. Data was recorded, managed, and analyzed using descriptive statistics. Statistical comparisons were made using t-tests. The results showed that, on time to runoff, rice straw mulch, PAM+lime, and PAM treatments increased the time to runoff on disturbed soil by 19.3%, 22.8%, and 8.8% respectively compared to the control treatment. However, lime and biochar did not have a significant effect on time to runoff on undisturbed soil. For surface runoff, rice straw mulch had the highest reduction, with a decrease of 28.8% in disturbed soil and 18.9% in undisturbed soil. In terms of infiltration rate, mulch had the highest increase, with 81% improvement in infiltration rate in both disturbed and undisturbed soil. In soil loss, mulch had the highest reduction, with a decrease of 63.7% in disturbed soil and 78.6% in undisturbed soil. Therefore, rice straw mulch and PAM treatments were particularly effective in improving these parameters and for sustainable land management practices