Irrigation and percolation management for reducing water footprint and nutrient leaching in rice-based ecosystems

Inefficient water management can lead to water and nutrient losses in rice cultivation, causing economic and environmental challenges. This study evaluated the effects of irrigation and percolation management on nutrient leaching, rice yield, and water footprint using field lysimeters during the Aman (wet) and Boro (dry) seasons in Mymensingh, Bangladesh. Irrigation treatments included zero ponding (saturated soil), 2-cm ponding, and 5-cm ponding, while percolation management involved uncontrolled percolation, reuse of percolated water, and no percolation. Leachate samples collected every 10 d were analyzed for mineral nitrogen and available phosphorus, with yield and water use measurements. The zero ponding treatment yielded lower water footprints in the Aman and Boro seasons (1 224 L/kg and 1 289 L/kg, respectively) than the 2-cm ponding (1 252 L/kg and 1 662 L/kg, respectively) and 5-cm ponding (1 360 L/kg and 1 953 L/kg, respectively) treatments, with comparable grain yields. The no-percolation treatment increased tiller count in the Aman season but had no significant effect in the Boro season. The uncontrolled percolation treatment resulted in total percolated water depths of 10–13 cm and 20–21 cm in the Aman and Boro seasons, respectively. The no-percolation treatment led to lower water footprints (1 224–1 289 L/kg) than the uncontrolled percolation (1 409–1 706 L/kg) and percolation-reuse (1 448–1 516 L/kg) treatments. Percolation reuse reduced phosphorus leaching in the Aman season, lowered NH 4 + - N leaching late in the Boro season, and decreased NO 3 − - N leaching in multiple events compared to uncontrolled percolation. These findings inform improved water and nutrient management strategies in rice ecosystems for enhanced sustainability.