Inefficient water management in rice paddy is responsible for a large quantity of water and nutrient loss, which causes tremendous economic and environmental costs. Yet, quantified data on the water and nutrient losses are limited. A study was conducted during 2018–2019 with an Aman (wet)-Boro (dry)-Aman (wet) rice rotation to evaluate the effect of water management on water and nutrient losses through different pathways. The treatments in 2018 Aman season were: (i) rainfed, (ii) I6D (irrigation after six days of ponded water disappearance), and (iii) I3D. In 2019, the Boro season had (i) I6D and (ii) I3D, and the Aman season had (i) rainfed, (ii) I9D, and (iii) I1D treatments. The water input and output from the studied lysimeters were measured daily, and samples from the leachates, ponded water, and topsoil were routinely analyzed for nutrient content. In both Aman seasons, the rainfed cultivation had lower percolation losses (38–44 % of total input) than other treatments (45–70 %). Evapotranspiration in the Boro season (5.4–5.9 mm/day) was higher than that in the Aman seasons (4.2–4.6 mm/day) because of the drier Boro season. Ammonium (NH₄⁺-N) leached at 0.6–6.7 mg/L and nitrate (NO₃⁻-N) 0.6–5.6 mg/L in these rice seasons. Phosphorus concentration ranged 0.04–0.37 mg/L in the leachates and 0.04–0.51 mg/L in the ponded water. The rainfed and I9D exerted higher nutrient leaching concentration in some events and less so for the I6D treatment than the I3D and I1D, possibly because of the better nitrification and preferential flow paths induced by the prolonged drying processes. However, the rainfed, I9D, and I6D had less leaching load than the I3D and I1D because the latter had larger percolation volume. For example, the I6D treatment in the Boro season reduced the N leaching load by 44 % and P load by 39 % compared with the I3D, and the I9D in 2019 Aman season had 42 and 13 % less N and P leaching load, respectively, than the I1D treatment. The findings will contribute to the effort of developing a sustainable and climate-resilient rice production system.

稻田水分管理效率低下，导致大量水分和养分流失，造成巨大的经济和环境成本。然而，关于水和养分损失的量化数据是有限的。在 2018-2019 年期间，通过 Aman（湿）-Boro（干）-Aman（湿）水稻轮作进行了一项研究，以评估水资源管理对通过不同途径造成的水和养分损失的影响。2018 年阿曼季节的处理方法是：(i) 雨养，(ii) I6D（池塘水消失六天后灌溉），和 (iii) I3D。2019 年，Boro 季节有 (i) I6D 和 (ii) I3D，而 Aman 季节有 (i) 雨育、(ii) I9D 和 (iii) I1D 处理。每天测量所研究的蒸渗仪的进水量和出水量，并从渗滤液、积水、定期分析表土和表土的养分含量。在两个阿曼季节，雨养栽培的渗透损失（占总投入的 38-44%）低于其他处理（45-70%）。由于波罗季节较干燥，波罗季节的蒸散量（5.4-5.9 毫米/天）高于阿曼季节（4.2-4.6 毫米/天）。铵（NH₄ ⁺-N) 以 0.6–6.7 mg/L 和硝酸盐 (NO ₃⁻-N) 0.6–5.6 mg/L 在这些水稻季节。渗滤液中磷的浓度范围为 0.04-0.37 毫克/升，池水中的磷浓度为 0.04-0.51 毫克/升。雨养和 I9D 在某些事件中施加更高的养分浸出浓度，而 I6D 处理的养分浸出浓度低于 I3D 和 I1D，这可能是因为延长的干燥过程导致更好的硝化作用和优先流动路径。然而，雨养、I9D 和 I6D 的浸出负荷低于 I3D 和 I1D，因为后者具有更大的渗滤量。例如，与I3D相比，Boro季节的I6D处理减少了44%的N浸出负荷和39%的P负荷，2019年Aman季节的I9D分别减少了42%和13%的N和P浸出负荷，比 I1D 治疗。