All soils released WEOC when shaken with water (no WEOC added; Fig.
To determine which soil properties influence WEOC sorption at, or close to, the maximum sorption capacity, correlations between WEOC sorption at 9 g WEOC [kg.
The batch sorption experiment showed that the WEOC sorption capacity of clay subsoils differed and was related to soil properties.
The high WEOC sorption capacity of soil 2 can further be explained by its low SAR and CROSS.
A high TOC concentration can reduce binding of added WEOC because native OC is already bound to the potential binding sites (Kaiser and Zech 2000), and only a limited proportion of clay surfaces contribute to OC binding (Vogel et al.
Yet soil 3 had similar, high WEOC sorption capacity.
Although soils 4, 5 and 7 had similar, medium WEOC sorption capacity, they differed in properties.
The WEOC sorption capacity, clay and TOC contents, and SSA in soil 7 were similar to those in soil 5, but SAR and CROSS were higher and the concentration of Fe oxides was lower in soil 7.
Despite high clay content and SSA, the WEOC sorption of soil 1 was low, which may be explained by its high TOC content, SAR and CROSS.
The shaking of the soils with the WEOC extracts was carried out at 4[degrees]C to minimise microbial decomposition of the WEOC during the shaking.