Adsorption on soil of dissolved organic carbon from farmyard manure

The adsorption of dissolved organic carbon (DOC) extracted from farmyard manure by ten acidic agricultural soils varying for different chemical properties was measured. Batch studies were conducted under the following conditions: 23 degrees C, pH 5.5, a 10:1 solution (0-18 mg DOC l(-1))/soil ratio and an ionic strength of 10(-3) M NaCl. The results of equilibration experiments showed that the amount of DOC removed or released in solution by the soil was a linear function of initial amount added to the soil-water system. Analysis of sorption isotherms was best described by the initial mass isotherm IM method. Among the IM isotherm parameters, the term m, representing a partition coefficient, was related to soil clay content, while the value b, the portion of the carbon reactive soil pool, was positively related to soil total and dissolved organic carbon, as well as with the anion exchange capacity. (C) 1998 Elsevier Science B.V. All rights reserved.