Table 2: Regression coefficients for the available forms of Cu and Zn extracted by DTPA and CaCl2; natural (independent variable) and acidified (dependent variable) samples.

Element/method Intercept Angular coefficient
Min.AverageMax.Min. AverageMax.

CuDTPA0.95−0.61−0.180.240.391.291.371.44<0.01
ZnDTPA0.94−0.88−0.170.530.621.061.131.20<0.01
CuCaCl0,150.0280.0330.038<0.010.0530.1260.200<0.01
ZnCaCl0.590.4010.6110.820<0.010.4800.6050.730<0.01