Effects of Soil Characteristics on Metribuzin Dissipation Using Clay−Gel-Based Formulations

详细信息    查看全文

• 作者：Celia Maqueda ; Jaime Villaverde ; Ftima Sopea ; Toms Undabeytia ; Esmeralda Morillo
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2009
• 出版时间：April 22, 2009
• 年：2009
• 卷：57
• 期：8
• 页码：3273-3278
• 全文大小：166K
• 年卷期：v.57,no.8(April 22, 2009)
• ISSN：1520-5118

文摘

Metribuzin (MTB) is a herbicide widely used for weed control in growing soybeans and other crops and has been identified in many parts of the world as a groundwater contaminant. To prepare controlled-release formulations (CRFs) of MTB, it was entrapped within a sepiolite-gel-based matrix with one of two proportions of clay/herbicide and used as either a gel or powder after freeze-drying. To determine how its persistence in soil is affected by formulation and soil type, MTB was applied as a CRF or commercial formulation (CM) to soils with different properties. MTB dissipation in all soils investigated was reduced when the herbicide was applied as CRFs, especially in the case of sandy soil and the freeze-dried formulations, with DT₅₀ values of 57.5 and 104.1 days, respectively, versus 24.8 days for CM. A positive relationship between degradation rates, bioactivity, and soil pH was found. MTB adsorption−desorption studies on these soils were also performed, and no relationship between adsorption−desorption and the degradation rate of MTB was found, possibly because of the low adsorption capacity of the studied soils. MTB when applied as a CRF remains active longer than CM, avoiding the need to use more frequently herbicide applications.