Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Pest Manag Sci. 2014 Mar;70(3):405-14. doi: 10.1002/ps.3574. Epub 2013 Jun 13.
Subsurface transport via tile drains can significantly contribute to pesticide contamination of surface waters. The spatial variation in subsurface leaching of normally applied herbicides was examined together with phosphorus losses in 24 experimental plots with water sampled flow-proportionally. The study site was a flat, tile-drained area with 60% marine clay in the topsoil in southeast Sweden. The objectives were to quantify the leaching of frequently used herbicides from a tile drained cracking clay soil and to evaluate the variation in leaching within the experimental area and relate this to topsoil management practices (tillage method and structure liming).
In summer 2009, 0.14, 0.22 and 1.62%, respectively, of simultaneously applied amounts of MCPA, fluroxypyr and clopyralid were leached by heavy rain five days after spraying. In summer 2011, on average 0.70% of applied bentazone was leached by short bursts of intensive rain 12 days after application. Peak flow concentrations for 50% of the treated area for MCPA and 33% for bentazone exceeded the Swedish no-effect guideline values for aquatic ecosystems. Approximately 0.08% of the glyphosate applied was leached in dissolved form in the winters of 2008/2009 and 2010/2011. Based on measurements of glyphosate in particulate form, total glyphosate losses were twice as high (0.16%) in the second winter. The spatial inter-plot variation was large (72-115%) for all five herbicides studied, despite small variations (25%) in water discharge.
The study shows the importance of local scale soil transport properties for herbicide leaching in cracking clay soils.
通过地下排水渠的地下运输可显著导致地表水污染的农药污染。本研究同时调查了通常应用的除草剂的地下淋溶的空间变化以及磷素流失，在 24 个实验区进行，每个实验区都采用比例采样法进行水样采集。研究地点位于瑞典东南部，是一个平坦的地下排水渠区，表土中 60%为海相粘土层。本研究的目的是量化从地下排水的裂缝粘土地区频繁使用的除草剂的淋溶，并评估实验区内的淋溶变化，并将其与表土管理措施（耕作方法和结构石灰）相关联。
2009 年夏季，施药后 5 天的强降雨使同时施用量的 MCPA、氟草烟和氯吡嘧磺隆分别淋溶了 0.14%、0.22%和 1.62%。2011 年夏季，施药后 12 天，短暂的强降雨使应用的苯达松平均有 0.70%被淋溶。MCPA 和苯达松的处理区有 50%和 33%的峰值流量浓度超过了瑞典水生生态系统无影响指导值。在 2008/2009 年和 2010/2011 年冬季，施用量的草甘膦约有 0.08%以溶解形式淋溶。基于草甘膦颗粒态的测量，第二年冬季总草甘膦损失（0.16%）是前者的两倍。尽管排水量变化较小（25%），但所有 5 种除草剂的研究结果表明，实验区之间的空间变异性较大（72-115%）。
该研究表明，在裂缝粘土地区，土壤的局部尺度传输特性对除草剂淋溶的重要性。
