Fig. 3. Relationship between the soil organic matter content for each soil and the fraction of applied napropamide retained in the treated layer following 100 mL of cumulative leachate and draining. 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.