Soil samples collected from four river basins in Karnataka were characterized for different physical and chemical parameters namely pH, EC, Organic carbon, Exchangeable cations (Ca2+, Mg2+, Na+, K+), Available nutrients (N,P,K), Cation exchange capacity, percent base saturation, SAR & ESP. Soil fertility evaluated by calculating Nutrient Index using OC and Available NPK values indicated that the soils of SLIS, SRLIS, Bellary nala and Varahi river basins respectively fall under high-low-low-low (HLLL), medium-low-low-medium (MLLM), high-medium-high-medium (HMHM) & low-low-low-low (LLLL) class. Applying organic wastes as a source of nutrient to the agricultural lands having low to medium %OC and Available nitrogen is required. Soils with low to medium phosphorus could be supplemented by applying phosphorous rich fertilizers as required by a specific crop. Soil samples with deficient and doubtful supply of potassium can be enriched with garden compost holding 0.48% K2O or vermicompost holding ~0.7% K2O. Estimation of CEC & base saturation help to maintain adequate cationic nutrients pool for plant uptake with less leaching losses.