TIDAL SWAMP RICE FIELDS HAVE GREAT POTENTIAL FOR AGRICULTURE, BUT OFTEN EXPERIENCE CONSTRAINTS IN THE FORM OF HIGH SOIL ACIDITY DUE TO THE PRESENCE OF PYRITE (FeS₂) AND ITS OXIDATION PROCESS. THIS STUDY WAS CONDUCTED TO DETERMINE THE CHEMICAL CHARACTERISTIC OF TIDAL SWAMP FIELDS SOILS IN MARTAPURA BARAT SUBDISTRICT, BANJAR REGENCY, SOUTH KALIMANTAN, FOCUSING ON DIFFERENCES IN pH, PYRITE CONTENT AND SOLUBLE SULFATE (SO₄^2-) BASED ON DISTANCE FROM THE RIVER AND SOIL DEPTH. THE RESEARCH USED AN EXPLORATORY DESCRIPTIVE METHODE WITH A SURVEY APPROACH. SAMPLES WERE TAKEN BY PURPOSIVE SAMPLING FROM TWO LOCATIONS 0.25 KM AND 3.25 KM FROM THE MARTAPURA RIVER, EACH AT TWO DEPTH (0-50 CM AND 50-100 CM). ANALYSES WERE CONDUCTED IN THE LABORATORY AND DATA WERE TESTED USING THE F-TEST AND T-TEST. THE RESULTS SHOWED THAT THE CHARACTERISTICS OF TIDAL RICE FIELD SOIL IN WEST MARTAPURA DISTRICT BASED ON DISTANCE FROM THE MARTAPURA RIVER (0.25 KM AND 3.25 KM) SHOWED THE SAME CHARACTERISTICS IN TERMS OF pH, PYRITE CONTENT AND SOLUBLE SULFATE. SOIL OXIDIZED WITH H₂O₂ SHOWED HIGHER SOLUBLE SULFATE THAN THAT WHICH WAS NOT OXIDIZED, THEREFORE MANAGEMENT OF RICE FIELDS IN THIS LOCATION MUST PAY ATTENTION TO SOIL AND WATER MANAGEMENT..