Fig. 2. Measured (symbols) and predicted P concentrations (lines) in 0.01 M CaCl₂ extracts with varying soil to solution ratios as a function of time at a fitted pore volume fraction of 0.035. The CaCl₂ extracts were obtained from the initial soil under mild shaking conditions in the batch experiments. The open triangle represents the P concentration measured in the 1:10 (w/v) 0.01 M CaCl₂ extract with vigorous shaking. The dotted line represents the predicted P concentration at a soil to solution ratio of 1:10 (w/v) whereby the radius of the spherical aggregate was set at 0.1 mm.