Research efforts dealing with the parameters and processes affecting the transport of herbicides in soils are needed in order to prevent further damage of surface and groundwater reserves. The present study was designed to improve the knowledge of the terbacil behaviour in soils by integrating adsorption/desorption and mobility experiments as related to soil characteristics. Hand-packed soil columns were used for the mobility experiments and simultaneously the sorption of terbacil was examined by the batch procedure. Four soils were used: two clay soil, a sandy clay soil and a sandy soil. The sorption parameters from Freundlich equation showed weak sorption, although it was higher and partially irreversible in the clay soils. The herbicide was found very mobile in the sandy soils and mobile in the clay soils with a leachate herbicide recovery ranging from 100 to 87 for the sandy and clay soils respectively. The elution profile and cumulative curves showed differences among the soils related to organic matter and clay contents and the combined influence of sorption (adsorption/desorption) and degradation processes are suggested. The mobility index calculated from the residue distribution along the soil column showed that terbacil mobility was inversely related with soil organic matter and with soil clay content, being highly correlated with the soil water flow, which also relates to the soil texture.
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