Tembotrione Half-Life in Soils with Different Attributes

ABSTRACT: Before recommending an herbicide, it is necessary to know its interactions with the soil attributes that will influence its sorption and half-life in the soil. This knowledge is an essential condition for minimizing any negative effects that may result from its application. However, due to the great diversity of soil and climate in Brazil, especially for products of recent use in the country, such as the herbicide tembotrione, this knowledge is often not available. This may be the main cause of occurrence of intoxication reports in crops carried out in succession to corn sprayed with this herbicide. In order to reduce possible impacts on successor crops and the contamination of surface and groundwater using the high-performance liquid chromatography, the tembotrione half-life was determined in soils with different attributes. The evaluated soils were a Red-Yellow Latosol with and without liming (Viçosa, MG), Red-Yellow Latosol (Rio Paranaíba, MG), Yellow Latosol (Sooretama, ES), and Red-Yellow Latosol with and without liming (Gurupi, TO). The results showed that liming might favor tembotrione degradation in the soil, as well as direct relationships between values of tembotrione half-life and contents of clay and soil organic matter. Tembotrione half-life in samples of Red-Yellow Latosol (without liming) collected in Viçosa and Rio Paranaíba, MG, was higher than 90 days, indicating carryover risks in successive crops to corn sprayed with tembotrione in these regions.

摘要：在推荐除草剂使用前，需明确其与土壤属性的相互作用——此类作用会直接影响该除草剂在土壤中的吸附行为与半衰期。该认知是降低除草剂施用可能引发的各类负面影响的必要前提。然而，受巴西土壤与气候类型多样性的影响，尤其是针对该国近年新近投入使用的除草剂品种（如苯唑草酮（tembotrione）），相关研究数据往往较为匮乏。这或为喷施该除草剂的玉米后茬作物出现药害报告的主要诱因。为降低对后茬作物的潜在危害以及地表、地下水的污染风险，本研究采用高效液相色谱法（high-performance liquid chromatography），对不同属性土壤中的苯唑草酮半衰期进行了测定。供试土壤包括：施与未施石灰的红黄色砖红壤（巴西米纳斯吉拉斯州维索萨市）、红黄色砖红壤（巴西米纳斯吉拉斯州里奥帕拉奈巴市）、黄色砖红壤（巴西圣埃斯皮里图州索雷托马市）以及施与未施石灰的红黄色砖红壤（巴西托坎廷斯州古鲁皮市）。研究结果显示，施用石灰可促进土壤中苯唑草酮的降解；同时，苯唑草酮的半衰期与土壤黏粒含量及有机质含量呈显著正相关。采自米纳斯吉拉斯州维索萨市与里奥帕拉奈巴市的未施石灰红黄色砖红壤样品中，苯唑草酮的半衰期均超过90天，表明在上述区域喷施苯唑草酮的玉米田，其后茬作物存在残留药害风险。