FATE OF METHABENZTHIAZURON IN CALCAREOUS SOILS FROM SOUTHEASTERN SPAIN

Adsorption, incubation, and soil column experiments with methabenzthia zuron [1-(1,3-benzothiazol-2-yl-)-1,3-dimethylurea] (MET) were carried out on soils from the surrounding fertile plain of Granada (southeast Spain). The isotherms of MBT adsorption followed the Freundlich model . Due to the similar physico-chemical and mineralogical properties of the soils from this area, the K-f values were only correlated with soi l clay content, smectite content, and soil surface area. Methabenzthia zuron degradation did not occur in the soils, under our experimental c onditions, for incubation periods of up to 42 d. Methabenzthiazuron wa s not detected in the eluates from the clay and silt loam soil columns ; it was retained in the first 3-cm layer and the retardation factor v alues, R, were 24 and 14, respectively. A computation model simulating a uniform flow of water and instantaneous adsorption-desorption equil ibrium is suitable for the description of MBT in the G-8 soil but show ed an overestimation in the G-11 soil column.