Department of Irrigation and Water Management, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh.
Department of Irrigation and Water Management, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh.
J Environ Manage. 2021 Nov 1;297:113402. doi: 10.1016/j.jenvman.2021.113402. Epub 2021 Jul 29.
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 (NH⁺-N) leached at 0.6-6.7 mg/L and nitrate (NO⁻-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.
稻田低效用水导致大量水和养分流失，造成巨大的经济和环境成本。然而，量化的水和养分损失数据有限。本研究于 2018-2019 年在一个稻作方式为水旱轮作（Aman-湿稻-Boro-干稻-Aman-湿稻）的田块进行，旨在评估不同水分管理措施对稻田水和养分通过不同途径损失的影响。2018 年 Aman 季的处理为：（i）雨养，（ii）淹水 6 天后灌溉（I6D），和（iii）淹水 3 天后灌溉（I3D）。2019 年 Boro 季的处理为（i）I6D 和（ii）I3D，Aman 季的处理为（i）雨养，（ii）淹水 9 天后灌溉（I9D）和（iii）淹水 1 天后灌溉（I1D）。通过每天测量研究蒸渗仪的水输入和输出，定期分析淋溶液、田面水和表土中的养分含量。在两个 Aman 季中，雨养处理的下渗损失（总输入的 38-44%）低于其他处理（45-70%）。由于 Boro 季较干燥，Boro 季的蒸发蒸腾量（5.4-5.9mm/d）高于 Aman 季（4.2-4.6mm/d）。这些水稻季中，铵态氮（NH⁺-N）的淋失浓度为 0.6-6.7mg/L，硝态氮（NO⁻-N）为 0.6-5.6mg/L。淋溶液中磷浓度范围为 0.04-0.37mg/L，田面水中为 0.04-0.51mg/L。在一些事件中，雨养、I9D 处理的养分淋失浓度高于 I6D 处理，而 I3D 和 I1D 处理则低于 I6D 处理，这可能是由于延长干燥过程诱导了更好的硝化作用和优先流路径。然而，由于后者具有更大的下渗体积，雨养、I9D 和 I6D 的淋失负荷小于 I3D 和 I1D。例如，与 I3D 相比，Boro 季的 I6D 处理减少了 44%的氮淋失负荷和 39%的磷淋失负荷，而 2019 年 Aman 季的 I9D 处理的氮和磷淋失负荷分别比 I1D 处理减少了 42%和 13%。这些发现将有助于开发可持续和适应气候变化的水稻生产系统的努力。
