Acid sulfate soils have potential for agricultural development. However, this soil has various properties problems that can inhibit plant growth. One way to improve soil properties is through the application of biochar amendments. The study aimed at knowing the role of rice husk biochar combined with amendments to Chromolaena odorata, rice straw, and rice husk ash to improve the properties of acid sulphate soil. The study was conducted in a greenhouse and arranged in a complete randomized design (CRD) with three replications. Biochar amendments consisted of nine kinds, namely, without amendments (control), C. odorata (10 t/ha), rice straw (10 t/ha), rice husk biochar (10 t/ha), rice husk ash (10 t/ha), C. odorata (10 t/ha)+rice husk biochar (5 t/ha), rice straw (10 t/ha)+rice husk biochar (5 t/ha), C. odorata (10 t/ha)+rice husk ash (5 t/ha), and rice straw (10 t/ha)+rice husk ash (5 t/ha). The results showed that the amendment of rice husk biochar combined with amendments to C. odorata and rice straw, respectively, had a good effect on improving soil physical properties, namely, total soil pores, reducing soil content weight and soil strength. Its effect on soil chemical properties was that it could increase pH, C-organic, P-available, cation exchange capacity (CEC), lower Al-dd and Fe soluble. The research findings showed that applying biochar and organic amendments to Chromolaena odorata and rice straw could potentially improve the properties of acid sulphate soil. In future research, we recommend increasing the carrying capacity of acid sulphate soil against plant growth, and it can be done by improving soil properties through the organic amendments’ application of C. odorata or straw enriched with rice husk biochar.