Fig. 5 Functional relations between concentrations of P_o extracted by resin (X) and the percentage of spectral area allocated to diester-P including teichoic acid-P (Y) for whole soils and for clay and silt separates. The full lines show the functional relations with the gradient b and the dotted lines are obtained by linear regression of Y on X (gradient = b_YX) and X on Y (gradient = 1/b_XY), respectively. For whole soils, the gradient b was 0.133, b_YX was 0.092, and 1/b_XY was 0.391; the correlation coefficient r² was 0.235. For the size separates, the gradient b was 0.974, b_YX was 0.862 and 1/b_XY was 0.928 and the correlation coefficient r² was 0.929. Land-use abbreviations are: Ar, arable rotation; Df, deciduous forest; Gp, permanent grassland; and Sf, spruce forest. Fertilizer-treatment abbreviations are: 0, unfertilized treatment; 2AM, animal manure treatment; 2NPK, inorganic fertilized treatment