This study aims to determine the effect of rice husk charcoal and swallow droppings on the chemical properties of acid sulfate soil, particularly on soil pH and the availability of potassium (K), phosphorus (P), and nitrogen (N). The study was carried out using a Completely Randomized Design (CRD) involving one factor, six treatments, and four replications, using acid sulfate soil from Sungai Rangas Village, South Kalimantan. Treatments consisted of combinations of various doses of rice husk charcoal and swallow droppings. The findings revealed that the incorporation of these organic amendments led to a significant increase in soil pH levels and the availability of NH??, NO??, available-P, and available-K. The best treatment for rice husk charcoal and swallow droppings was found in A2.5W5 for pH (6.90) and available nitrogen (NH??) (59.53 mg kg?¹), A2.5W2.5 for available nitrogen (NO??) (33.00 mg kg?¹), A0W5 for available phosphorus (19.35 ppm P), and A5W2.5 for available potassium (0.13 cmol kg?¹). Although the highest values were observed for each parameter, some results were not significantly different. Therefore, treatments that do not require large amounts of rice husk charcoal or swallow droppings were selected to be more economical.