Grasslands include some of the most endangered and less protected ecosystems on the planet, such as the Pampa of South America. In the Flooding Pampa where native grasslands were not replaced by crops, glyphosate is frequently sprayed in late-summer every year to increase winter forage productivity for cattle without knowing the impacts on both aboveground and belowground grassland genetic resources. Here, we evaluated the effect of this practice on the abundance and community structure of members of the genus Pseudomonas, one of the most diverse bacterial taxa of the plant rhizosphere broadly recognized by their benefits on plant growth and protection, and on soil remediation. In a field experiment, we analyzed the impact of a single application or of a repeated annual application during 4 consecutive years of the recommended dose of commercial glyphosate (Glacoxan®, 3 l ha^-1 and 1440 g active ingredient ha^-1). In a greenhouse experiment, we tested whether exposure of bare soil to either commercially formulated or pure glyphosate has a direct impact on the resident pseudomonas community in the absence of plants. In the field, we found that the repeated annual herbicide application resulted in a reduction in the abundance and a shift in the community structure of culturable pseudomonads, with evidence of an enrichment of glyphosate-metabolizing lineages. On the other hand, a single application of glyphosate to bare soil under greenhouse conditions did not affect the abundance nor the community structure of pseudomonads. Considering that these plant-beneficial bacteria are natural inhabitants of the rhizosphere and that their fitness is promoted by plant root exudates, the observed alterations are most likely associated with the drop in the vegetation cover directly provoked by the effect of glyphosate. For the first time, we report on the consequences that a reiterated glyphosate application has on a diverse soil reservoir of bacteria that contributes to crucial ecosystem functions in a temperate natural grassland under animal production. Our findings strengthen the notion that this agronomical practice has an unavoidable imprint on non-target microorganisms that are relevant components of the plant-soil feedbacks and that may be instrumental for ecosystem restoration. We conclude that it is necessary to develop sustainable management practices to avoid affecting key functional microorganisms and exploit their contributions to society.

草原包括地球上一些最濒危和保护较少的生态系统，例如南美洲的潘帕草原。在原生草原没有被作物取代的洪泛潘帕，草甘膦经常在每年夏末喷洒，以提高牛的冬季饲料生产力，但不知道对地上和地下草原遗传资源的影响。在这里，我们评估了这种做法对假单胞菌属成员的丰度和群落结构的影响，植物根际最多样化的细菌分类群之一，因其对植物生长和保护以及土壤修复的益处而被广泛认可。在田间试验中，我们分析了连续 4 年推荐剂量的商业草甘膦（Glacoxan®，3 l ha ^-1和 1440 g 活性成分 ha ^-1）。在温室实验中，我们测试了在没有植物的情况下，裸土暴露于商业配方或纯草甘膦是否对常驻假单胞菌群落有直接影响。在田间，我们发现每年重复使用除草剂会降低可培养假单胞菌的丰度并改变其群落结构，这证明了草甘膦代谢谱系的丰富。另一方面，在温室条件下对裸土单次施用草甘膦不会影响假单胞菌的丰度和群落结构。考虑到这些对植物有益的细菌是根际的天然居民，并且它们的适应性受到植物根系分泌物的促进，观察到的变化很可能与草甘膦的作用直接引起的植被覆盖率下降有关。我们第一次报告了重复使用草甘膦对多样化土壤细菌库的影响，这些细菌在动物生产的温带天然草原中有助于关键的生态系统功能。我们的研究结果强化了这样一种观点，即这种农艺实践对非目标微生物有不可避免的影响，这些微生物是植物-土壤反馈的相关组成部分，可能有助于生态系统恢复。我们得出的结论是，有必要制定可持续的管理实践，以避免影响关键功能微生物并利用它们对社会的贡献。我们报告了重复使用草甘膦对多样化土壤细菌库的影响，这些细菌对动物生产的温带天然草原中的关键生态系统功能有贡献。我们的研究结果强化了这样一种观点，即这种农艺实践对非目标微生物有不可避免的影响，这些微生物是植物-土壤反馈的相关组成部分，可能有助于生态系统恢复。我们得出的结论是，有必要制定可持续的管理实践，以避免影响关键功能微生物并利用它们对社会的贡献。我们报告了重复使用草甘膦对多样化土壤细菌库的影响，这些细菌对动物生产的温带天然草原中的关键生态系统功能有贡献。我们的研究结果强化了这样一种观点，即这种农艺实践对非目标微生物有不可避免的影响，这些微生物是植物-土壤反馈的相关组成部分，可能有助于生态系统恢复。我们得出结论，有必要制定可持续的管理实践，以避免影响关键功能微生物并利用它们对社会的贡献。我们的研究结果强化了这样一种观点，即这种农艺实践对非目标微生物有不可避免的影响，这些微生物是植物-土壤反馈的相关组成部分，可能有助于生态系统恢复。我们得出结论，有必要制定可持续的管理实践，以避免影响关键功能微生物并利用它们对社会的贡献。我们的研究结果强化了这样一种观点，即这种农艺实践对非目标微生物有不可避免的影响，这些微生物是植物-土壤反馈的相关组成部分，可能有助于生态系统恢复。我们得出的结论是，有必要制定可持续的管理实践，以避免影响关键功能微生物并利用它们对社会的贡献。