Rainfall is one of the climate factors that strongly affect swampland paddy cultivation regarding its water conditions in the rainy season. The research aimed to identify the paddy planting time in freshwater and tidal swampland based on monthly rainfall. Rainfall data were obtained from Climate Hazards Center Infrared Precipitation with Stations data (CHIRPS) for 20 years (2000 to 2019). Planting area and planting time data were collected from field surveys through interviews with local farmers and agricultural extension agents. This study has conducted a descriptive analysis of harvest area data and annual rainfall rate. The Result showed paddy cultivation in freshwater affected by land typology and monthly rainfall. Planting time of paddy in shallow swamp begin in March or April. In the medium swamp area, planting time starts in June. While planting time in the deep swamp starts in August. In the tidal swamp, paddy cultivation for type C was more affected by rainfall. Local farmers in freshwater swamp plant paddy once a year, while in the tidal swamp, farmer can cultivate crop twice a year, namely paddy and corn.

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Indonesia has various rainfall characteristics that result variations in the initial planting time and cropping patterns. The Integrated Cropping Calendar Information System is a guidance for planting rice, maize, and soybean at the right time with sufficient water availability conditions. This paper aimed to analyse the planting schedule and potential planting area of rice, maize, and soybeans in the dry season 2020 at 7,062 sub-districts in Indonesia. Input data were rainfall prediction, spatial-based ETP, soil water availability, wetland area, and rice cropping index. The stages were the analyses on rainfall, calculating soil water balance, and determining potential planting area. The results illustrated that the mean rainfall intensity and rainfall intensities of <60 and 200-300 mm mo−1 were predicted as the widest rainfall coverages in April-June and July-September. The potential planting areas for rice, maize, and soybean were 5,259,661, 1,263,575, and 559,545 ha, respectively. Rice and maize initial planting periods were mainly in April II-II, while soybean in July III-August. Potential planting area for rice can be expanded to become 6,674,428 ha by applying additional water supply from alternative sources at the potential areas of maize and soybean.