Swamp land in Indonesia covers an area of ??34.93 million ha spread over various islands such as Sumatra, Java, Kalimantan, Sulawesi, and Papua. One type of swamp land that is often used in agriculture is tidal land. The problems faced in the development of tidal land into agricultural land include acid soil pH, high levels of soluble Fe and Al-dd. One of the efforts to overcome the problem of acidic soil pH, high levels of soluble Fe and Al-dd by using lime. The finer grain level of lime can increase the effectiveness of liming. The purpose of this study was to determine the effect of lime grain size on changes in pH, dissolved Fe, and Al-dd in tidal land. This study used a one-factor Completely Randomized Design (CRD) consisting of 6 treatments (Control; CaCO₃ more than 1.00 mm (> 18 mesh); CaCO₃ lime, 0.5-100 mm (18 -35mesh); CaCO₃ measuring 0.21-0.50 mm (35-70 mesh); CaCO₃ measuring 0.21 mm (<70 mesh); CaCO₃ lime measuring 0.15-1.00 mm (18 -100 mesh)). The results showed that the difference in the size of the CaCO₃ lime granuleshad a significant effect on changes in pH, soluble Fe and Al-dd. Giving CaCO₃ lime granules0.21 mm (<70 mesh) can increase pH, suppress soluble Fe and Al-dd levels.