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Iron toxicity in rice plants occurs due to the excessive concentrations of ferrous ions (Fe2+) in the soil solution. The application of organic matter and water management is one way to alleviate iron toxicity in rice plants. This study aimed to determine the potential of organic matter and water management in controlling the solubility of Fe2+ in the soil and its effect on the symptoms of toxicity, growth and yield of rice plants. The research was conducted in the greenhouse of the Indonesian Swampland Agricultural Research Institute from August to December 2020, arranged in a completely randomized design with three factors. The first factor consisted of low Fe2+ concentration (300 ppm, potential acid sulfate soil (PASS)), the second factor consisted of waterlogging without leaching and leaching of once every two weeks, and the third factor consisted of without organic matter amendment and with organic matter amendment of 2.5 ton.ha-1. In comparison to the treatment of without organic matter amendment and leaching, the organic matter and leaching treatment in the AASS reduced the leaf bronzing index by 26.17 % and increased the crop yield by 21.20 %. In the PASS, the organic matter and leaching treatment reduced the leaf bronzing index by 11.74 % and increased the crop yield by 15.72 %. The leaching of once every two weeks and organic matter amendment of 2.5 ton.ha-1 are recommended to alleviate iron toxicity and increase rice productivity in acid sulfate soil.

Subsurface drainage technology may offer a useful option in improving crop productivity by preventing water-logging in poor drainage paddy fields. The present study compared two paddy fields with and without sheet-pipe type subsurface drainage on land and water productivities in Indonesia. Sheet-pipe typed is perforated plastic sheets with a hole diameter of 2 mm and made from high-density polyethylene. It is commonly installed 30–50 cm below the soil surface and placed horizontally by a machine called a mole drainer, and then the sheets will automatically be a capillary pipe. Two fields were prepared, i.e., the sheet-pipe typed field (SP field) and the non-sheet-pipe typed field (NSP field) with three rice varieties (Situ Bagendit, Inpari 6 Jete, and Inpari 43 Agritan). In both fields, weather parameters and water depth were measured by the automatic weather stations, soil moisture sensors and water level sensors. During one season, the SP field drained approximately 45% more water compared to the NSP field. Thus, it caused increasing in soil aeration and producing a more significant grain yield, particularly for Inpari 43 Agritan. The SP field produced a 5.77 ton/ha grain yield, while the NSP field was 5.09 ton/ha. By producing more grain yield, the SP field was more effective in water use as represented by higher water productivity by 20%. The results indicated that the sheet-pipe type system developed better soil aeration that provides better soil conditions for rice.