Department of Crop Production, Universidade Federal do Espírito Santo, Alegre, ES, Brazil.
Department of Crop Production, Universidade Federal Rural do Semi-Árido, Mossoró, RN, Brazil.
Environ Sci Pollut Res Int. 2018 Aug;25(24):23986-23991. doi: 10.1007/s11356-018-2443-y. Epub 2018 Jun 8.
Herbicides with long residual period may increase the risk of environmental contamination. Adequate management of forage can reduce the half-life of the picloram, one of the most herbicides used in weed control. This study aims to determine the half-life of picloram, using high-performance liquid chromatography in a cultivated soil with Brachiaria brizantha trimmed or not. Brachiaria brizantha was cultivated in 60 pots filled with samples of oxisol, and 30 others were kept uncultivated with this forage. This plant was cut off close to the ground, after 60 days of emergency on 30 vessels. Picloram was applied in all of the plots. Soil samples were collected at 2, 16, 30, 44, 58, 72, 86, 120, 150, and 180 days after the application of this herbicide. These samples were air-dried and stored at - 20 °C. Picloram was extracted by HPLC/UV-Vis detector. Half-life of this herbicide was calculated using kinetics models. The mere presence of roots in treatment with signalgrass cutoff did not reduce the concentrations of this herbicide, except when the emergence of new leaves occurred. The absence of B. brizantha cultivation in areas with application of picloram increases the risk of environmental contamination and successive crops due to the half-life of this herbicide. Brachiaria brizantha reduced half-life picloram and environmental risk in pastures. The validation method is suitable for determining picloram in low concentrations in soil.
残留期长的除草剂可能会增加环境污染的风险。通过适当管理饲料，可以缩短在杂草控制中使用最广泛的除草剂之一——百草枯的半衰期。本研究旨在使用高效液相色谱法，确定修剪或不修剪的狗尾草种植土壤中百草枯的半衰期。在 60 个装满氧化土样本的盆中种植狗尾草，另外 30 个盆不种植狗尾草作为对照。这种植物在紧急情况下种植 60 天后，离地 60 天被剪短。所有的地块都喷洒了百草枯。在施药后 2、16、30、44、58、72、86、120、150 和 180 天采集土壤样本。这些样本风干后储存在-20°C。用高效液相色谱/紫外可见检测器提取百草枯。通过动力学模型计算这种除草剂的半衰期。仅仅在有狗尾草的处理中存在根系并没有降低这种除草剂的浓度，除非出现新的叶片。在施药区不种植狗尾草会增加环境污染和后续作物的风险，因为这种除草剂的半衰期较长。狗尾草降低了百草枯的半衰期和牧场的环境风险。该验证方法适用于测定土壤中低浓度的百草枯。
