Mendes Kassio Ferreira, Martins Bianca Assis Barbosa, Dos Reis Marcelo Rodrigues, Pimpinato Rodrigo Floriano, Tornisielo Valdemar Luiz
University of São Paulo, Center of Nuclear Energy in Agriculture, Piracicaba, SP, Brazil.
University Federal of Viçosa, Rio Paranaíba, MG, Brazil.
Environ Sci Pollut Res Int. 2017 Mar;24(9):8425-8435. doi: 10.1007/s11356-017-8535-2. Epub 2017 Feb 10.
The effects of mesotrione, S-metolachlor, and terbuthylazine, applied in mixture, on soil biodegradation remain insufficiently researched. However, herbicide mixtures have been a common practice in agricultural systems in the last years. Understanding the fate of soil-applied herbicides may help on planning weed management tactics towards more sustainable and efficient weed control. Therefore, this study evaluated the fate of mesotrione alone and in mixture with S-metolachlor and terbuthylazine when applied to two contrasting arable Brazilian soils. Mineralization and degradation experiments were conducted using C-mesotrione alone or in mixture. From the 49-day laboratory incubation data, increased mineralization half-life of mesotrione was observed for the mixture of herbicides, ranging from a 4-day increase for the sandy loam soil to a 1-day increase in the sandy clay texture soils. Mesotrione degradation rate had a twofold increase in the sandy loam compared to the sandy clay soil. Two metabolites can be identified from mesotrione degradation, 4-methyl-sulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4-methylsulfonyl benzoic acid (AMBA). Indices for the score of ubiquity in groundwater indicated mesotrione possesses leaching potential for both soils. Applying mesotrione alone or in mixture did not influence the amount of bound residues from mesotrione. However, mesotrione degradation rate was influenced by soil texture regardless if applied alone or in mixture. Mesotrione biotransformation was relatively quick, indicating that this herbicide has low persistence and, consequently, low residual effect on crops and weeds when present in similar soils to this present study.
甲基磺草酮、异丙甲草胺和特丁津混合施用对土壤生物降解的影响仍未得到充分研究。然而，在过去几年中，除草剂混合使用在农业系统中已很常见。了解土壤施用除草剂的归宿有助于规划杂草管理策略，以实现更可持续和高效的杂草控制。因此，本研究评估了甲基磺草酮单独施用以及与异丙甲草胺和特丁津混合施用时在巴西两种不同耕地土壤中的归宿。使用单独的或混合的碳-甲基磺草酮进行矿化和降解实验。根据49天的实验室培养数据，观察到除草剂混合物使甲基磺草酮的矿化半衰期增加，从砂壤土中增加4天到砂质粘土质地土壤中增加1天。与砂质粘土土壤相比，甲基磺草酮在砂壤土中的降解速率增加了两倍。从甲基磺草酮的降解中可以鉴定出两种代谢物，4-甲基磺酰基-2-硝基苯甲酸（MNBA）和2-氨基-4-甲基磺酰基苯甲酸（AMBA）。地下水中普遍存在得分指数表明甲基磺草酮在两种土壤中均具有淋溶潜力。单独施用或混合施用甲基磺草酮均不影响甲基磺草酮结合残留量。然而，无论单独施用还是混合施用，甲基磺草酮的降解速率都受土壤质地影响。甲基磺草酮的生物转化相对较快，表明该除草剂持久性低，因此，当存在于与本研究类似的土壤中时，对作物和杂草的残留影响较小。
