Raising a sandy soil's ability to retain more water is an important strategy to manage sandy soils. Combined application of biochar and slurry was hypothesized to be an appropriate strategy for improving soil hydro-physical properties. A two-season field trial was conducted by cultivating peanut (Arachis hypogaea L.) on a sandy soil under permanent overhead sprinkler irrigation. Rice straw biochar at 0, 10, 20 and 30 Mg ha−1 and biogas slurry at 0, 5, 10 and 15 Mg ha−1 were applied. Results indicated that all biogas slurry rates were more effective than biochar on improving all investigated parameters apart from infiltration rate and hydraulic conductivity which were higher with 30 Mg ha−1 of biochar than with 15 Mg ha−1 of slurry. Soil bulk density (g m−3) decreased significantly from 1.76 for the control to record 1.72 and 1.62 under biochar and slurry, respectively. Soil moisture contents at different tensions were the highest under the maximum combination rates, while biochar singly gave lower contents than slurry. The combined effect of 10 and 15 Mg ha−1 biochar and slurry, respectively, surpassed their individual effects. With strong coefficients of determination (R2 ranges from 0.88 to 0.98) and identical curves of estimated and predicted variables, it is possible to have accurate predictions for the changes in soil hydro-physical properties linked with different combinations of biochar and biogas slurry