Fig. 6. Relationship for the soils of the 5- and 10-cm treatments between the average P concentration, calculated from the P concentration measured in 1:10 (w/v) 0.01 M CaCl₂ extracts at two subsequent sampling points, and the P content of the grass harvested since the previous sampling point. The filled symbols of the 5- and 10-cm treatments, representing the average P concentration in the CaCl₂ extracts at t0 and t1 and the P content of the grass harvested since t0, were not included in the linear regression analysis, because these data points deviate significantly from the line.