Sorption of dissolved organic C and P to agricultural top- and subsoil

In order to study the mobility of dissolved organic carbon (DOC) and dissolved organic P (DOP) in soil, the pH-dependent sorption of dissolved organic matter to an agricultural top- and subsoil was investigated. In general, sorption isotherms had convex shapes and DOC and DOP sorption increased with time of reaction. There was a very pronounced effect of pH resulting in much higher sorption of DOC at pH 5 than at pH 7; actually extensive desorption was observed at pH 7 especially for the topsoil. Similar sorption patterns were observed for DOP, but they were not as pronounced as for DOC