Fig. 3. Pearson correlation coefficients between crop yield and (a) apparent electrical conductivity measured at 0- to 30-cm depth (ECs) and (b) apparent electrical conductivity measured at 0- to 90-cm depth (ECd), and SC (parameter characterizing statistically significant spatial correlation between the variables) values for crop yield and (c) ECs and (d) ECd plotted vs. maximum daily March precipitation.