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Soil Column Mobility of Metribuzin from Alginate-Encapsulated Controlled Release Formulations of metribuzin
- Johnson, Richard M., Pepperman, Armand B.
- Journal of Agricultural and Food Chemistry 1995 v.43 no.1 pp. 241
- calcium chloride, encapsulation, herbicide residues, kaolin, leaching, linseed oil, metribuzin, sodium alginate, soil horizons, soil profiles
- The mobility of metribuzin [4-amino-6-(1,1-dimethylethyl)-3-methylthio)-1,2,4-triazin-5(4H)-one] from alginate-encapsulated controlled release (CR) was investigated in four contrasting soil profiles. Two CR formulations based on sodium-alginate (1%), kaolin (10%) and Tween 20 (0.5%) were compared to technical grade (TG) metribuzin and to a commercial liquid (CL) metribuzin formulation (Sencor 4L). In addition to the basic components, the CR-Oil formulation contained 4% linseed oil and the (CR-N) formulation did not. All herbicide treatments were labeled with [14C]-metribuzin and were applied to duplicate soil columns containing a surface and a subsoil horizon. Each horizon was packed to a depth of 12.5 cm, giving a tolal column length of 25 cm. The columns were leached with 21 (420 mL) to 30 cm (600 mL) of 0.01 M CaCl2 for a period of 7-10 days. For the TG treatment, the total amounts of [14C]metribuzin leached were 85, 62, 66 and 58% for the Evesboro, Ocholocknee, Conover and Commerce soils, respectively. This is compared to 91, 52, 51 and 43% for the CL formulation. The CR-Oil formulation leached 9, 13, 9, and 9% of the applied [14C]metribuzin, compared to 49, 53, 41, and 48% for the CR-N formulation. The CR-Oil formulation also increased the amount of [14C]metribuzin retained in the soil surface horizon (13-27%), compared to CR-N (2-5%), TG (2-3%,) and CL (1-2%) formulations.