Mitigating Iron Toxicity and Enhancing Rice Growth Through Periodic Flooding in Tropical Ultisol Fields with Low Productivity

Iron toxicity is a major constraint in rice cultivation on tropical Ultisol soils, particularly in fields with a history of low productivity. Continuous flooding in paddy systems exacerbates this issue by increasing Fe²⁺ availability, leading to toxicity at high concentrations. This study evaluated periodic flooding and drying as a sustainable water management strategy to mitigate Fe²⁺ toxicity and enhance rice growth. A greenhouse experiment was conducted using a completely randomized design with five treatments and five replications, assessing different flooding and drying intervals. Soil pH and Fe²⁺ concentrations were measured at the end of the experiment, along with key rice growth and yield parameters. Results showed that extended drying intervals significantly improved soil pH and reduced Fe²⁺ concentrations, mitigating toxicity. The treatment with three weeks of drying followed by three weeks of flooding resulted in the lowest Fe²⁺ concentration (4.08 ppm) and the most stable pH conditions. However, the highest rice productivity was observed in the two-week flooding–two-week drying treatment, which promoted increased plant height, tiller number, and grain yield. These findings highlight the potential of periodic flooding as a practical and sustainable approach to improve soil health and rice productivity in iron-toxic Ultisol fields. This study contributes to developing effective water management strategies for rice cultivation in marginal tropical soils, addressing both environmental sustainability and agricultural productivity. Future research should explore the long-term impacts of periodic flooding on soil nutrient dynamics and its applicability across diverse tropical agroecosystems