农田水位管理系统地下排水磷淋失实验研究

The Effects of Water Table Management on Phosphorus Leaching Loss in the Farmland Drainage

农田控制排水对减少土壤养分淋失、保护农田水环境具有重要作用。为探讨影响地下排水磷淋失量的要素,基于田间实验小区观测资料,统计分析了玉米作物生长期间农田水位管理系统运行对地下排水量和磷淋失量的影响,结果表明,与暗管自由排水系统相比,农田水位管理系统下的累积排水总量约减少1/3,但次地下排水磷淋失浓度和地下排水总磷累积淋失量均明显增高。农田水位管理系统下存在的土壤持续性饱和厌氧状态造成地下排水中氧化还原电位Eh的明显降低和pH值及可溶解性Mn和Fe浓度的显著增大,这或许是导致该系统地下排水磷淋失量明显高于暗管自由排水系统的主要影响因素。

It is significant that the nutrients loss could be reduced and the water environment could be protected via controlled drainage.The effects of water table management system on the outflow volumes of sub-surface drainage and phosphorous leaching loss were statistically analyzed during the growing season of corn.The results showed that the total outflow volumes were reduced about 1/3 from water table management system compared to free drainage system.However,the concentration of phosphorus（P）of drainage and the total phosphorus leaching loss were significant higher under water table management system than free drainage system.At the meantime,the oxidation-reduction potential（Eh） was lower and pH value and concentration of dissolved Mn and Fe were higher in water table management system compared to free drainage system.These results indicated that the increased P leaching loss in drainage under water table management system were most likely caused by an increase in P solubility due to continuously anaerobic condition which aroused the changes of values of Eh,pH and concentration of Mn and Fe.