Purple soil, as a key agricultural resource in Southwest China, is increasingly threatened by the synergistic effects of acidification and nutrient depletion, posing significant challenges to regional sustainable agriculture. However, traditional soil conditioners such as lime and biochar have numerous limitation. In this study, the acid suppression and quality enhancement effects of calcium lignosulfonate (LC) and mineral-derived potassium fulvate (HA), two base cation-rich organic amendments, were evaluated across three purple soils derived from different parent materials. Results showed that combined application of LC (1g/kg) and HA (1g/kg) significantly increased soil pH and enhanced acid buffering capacity, with the most pronounced effect observed in the strongly acidic Jiaguan group (K2j), where exchangeable Al3+ was reduced by 97.24%. Additionally, compared to conventional chemical fertilizer treatment (CK), LC and HA significantly promoted maize growth, with photosynthetic rate increasing by 13.11%–39.75% (p < 0.05) and 100-grains weight increasing by more than 70.33%. These findings demonstrate that base cation-enriched organic amendments can simultaneously improve soil fertility and crop productivity in acidified purple soils by immobilizing exchangeable Al3+, replenishing base cations, and enhancing SOM content. The amendment effects varied depending on the soil parent material and initial acidity. This study provides both theoretical support and a practical strategy for improving cultivated land quality and advancing green agriculture in Southwest China.