Mamy Laure, Gabrielle Benoit, Barriuso Enrique
INRA, UMR1091 Environnement et Grandes Cultures, 78850 Thiverval-Grignon, France.
Pest Manag Sci. 2008 Mar;64(3):262-75. doi: 10.1002/ps.1519.
Crops resistant to glyphosate may mitigate the increasing contamination of the environment by herbicides, since their weeding requires smaller amounts of herbicides and fewer active ingredients. However, there are few published data comparing the fate of glyphosate with that of substitute herbicides under similar soil and climatic conditions. The objectives of the work reported here were (i) to evaluate and compare the fate in soil in field conditions of glyphosate, as used on glyphosate-resistant oilseed rape, with that of two herbicides frequently used for weed control on the same crop, albeit non-resistant: trifluralin and metazachlor, and (ii) to compare field results with predictions of the pesticide root zone model (PRZM), parameterized with laboratory data. Dissipation and vertical distribution in the soil profile of glyphosate, trifluralin and metazachlor were monitored in an experimental site located in Eastern France for 1 year.
Herbicide persistence in the field increased as follows: metazachlor < glyphosate < trifluralin, contrary to laboratory results showing glyphosate to be least persistent. The main metabolite of glyphosate-aminomethylphosphonic acid (AMPA)-was more persistent than glyphosate. AMPA and trifluralin had the largest vertical mobility, followed by metazachlor and glyphosate. PRZM underestimated the dissipation rate of glyphosate in the field and the formation of AMPA, but its predictions for trifluralin and metazachlor were correct. The simulation of herbicides and AMPA distribution in the soil profile was satisfactory, but the mobility of trifluralin and metazachlor was slightly underestimated, probably because PRZM ignores preferential flow. In general, data from the laboratory allowed an acceptable parameterization of the model, as indicated by goodness-of-fit indices.
Because of the detection of AMPA in the deep soil layer, the replacement of both trifluralin and metazachlor with glyphosate might not contribute to decreasing environmental contamination by herbicides. PRZM may be used to evaluate and to compare other weed control strategies for herbicide-resistant as well as non-resistant crops.
抗草甘膦作物可能会减轻除草剂对环境日益增加的污染，因为其除草所需的除草剂用量较少且活性成分较少。然而，在相似的土壤和气候条件下，比较草甘膦与替代除草剂归宿的已发表数据很少。本文报道的研究目的是：（i）评估并比较抗草甘膦油菜使用的草甘膦与两种常用于同一作物（非抗性作物）除草的除草剂（氟乐灵和异丙甲草胺）在田间条件下在土壤中的归宿；（ii）将田间结果与根据实验室数据参数化的农药根区模型（PRZM）的预测结果进行比较。在法国东部的一个试验地点对草甘膦、氟乐灵和异丙甲草胺在土壤剖面中的消散和垂直分布进行了为期1年的监测。
除草剂在田间的持久性增加顺序如下：异丙甲草胺＜草甘膦＜氟乐灵，这与实验室结果显示草甘膦持久性最低相反。草甘膦的主要代谢物氨甲基膦酸（AMPA）比草甘膦更持久。AMPA和氟乐灵具有最大的垂直迁移性，其次是异丙甲草胺和草甘膦。PRZM低估了田间草甘膦的消散速率和AMPA的形成，但其对氟乐灵和异丙甲草胺的预测是正确的。除草剂和AMPA在土壤剖面中的分布模拟结果令人满意，但氟乐灵和异丙甲草胺的迁移性被略微低估，可能是因为PRZM忽略了优先流。总体而言，拟合优度指标表明，实验室数据可为该模型提供可接受的参数化。
由于在深层土壤层中检测到了AMPA，用草甘膦替代氟乐灵和异丙甲草胺可能无助于减少除草剂对环境的污染。PRZM可用于评估和比较抗除草剂作物及非抗除草剂作物的其他杂草控制策略。
