Sorption of metamitron on soils with low organic matter content

The adsorption of the herbicide metamitron (4-amino-4,5-dihydro-3-methyl-6phenyl-1,2,4-triazin-5-one) by 21 soil samples corresponding to different horizons of 13 soils located in Southern Spain has been studied following a batch equilibration procedure. Soil organic matter ranged from 0.3 to 2.5, being the mean value 1.0, and soil clay content from 3 to 70, being the mean value 35. X-Ray diffraction analysis of the soil clays indicated that illite is the most important component of soils clay fraction. Adsorption isotherms indicated a medium to low sorptivity of metamitron on the soils studied and revealed soil clay, and specially soil illite, as the most important single property affecting the adsorption of this herbicide in soils.