Propyzamide herbicide Cl(2)C(6)H(3)CONHCMe(2)C CH (1) was adsorbed from aq. solns. (concn. 50 mg/L) on dry or humid (15%) soils in presence of HumiPlant prepn. (0.01 or 0.1 g/L) to det. the adsorption kinetics. Addn. of the HumiPlant prepn. resulted in an acceleration of the I adsorption. It was completed after 6 h. The max. I adsorption was 92.5% on the dry soil and 89.5% on the humid one. The highest concn. of I was achieved on the dry soil (96.2 mg/kg).