| Abstract: | The effect of aggregation on nutrient release by diffusion has been determined for potassium for a well structured P horizon of a Vertic Cambisol. The results clearly demonstrate that homogenization of soil material produces an increase of the potassium release by diffusion compared to that from single natural aggregates. The bigger the aggregates are the smaller is the potassium release related to unit mass per unit time, because of the longer flow paths in bigger aggregates. If the results are related to unit surface, bigger aggregates deliver significantly more potassium because of the smaller inter-aggregate surfaces. Differences between potassium release out of differently sized aggregates further depend on the kind of extraction liquid. Values of the effective diffusion coefficient for potassium are smaller for single aggregates than for undisturbed soil samples. |
