Fig. 2. Relationship between soil organic matter content (closed symbols) and the ratio of the K1/K2 solution K_d's (open symbols) and for each treatment and fraction of applied napropamide leached in the first 30 mL of effluent. Napropamide was applied to soil allowed to dry and a 5-cm treated soil layer was placed over a 10-cm untreated layer and irrigated with a constant head. Error bars are ±1 standard error of the mean. In some cases error bars are smaller than the symbols.