Use of Correlation Relationships to Enhance Understanding of Pedogenic Processes and Use Potential of Vertisols and Vertic Inceptisols of the Bale Mountain Area of Ethiopia
Five Vertisols and two Vertic Inceptisols developed from basalt and alluvial materials were characterized for physical and chemical properties. Correlative statistical relationships were established among physical and chemical properties including cation exchange capacity (CEC), percent total clay, electrical conductivity (EC), base saturation % (BS), pH-H2O, pH-KCl, CaCO3 equivalent, organic carbon (OC), total nitrogen (TN), P-Bray and P-Olsen. Correlative relationships were established among parameters for all horizons of the soils studied as well as among parameters within individual horizons. P-Olsen was highly correlated with OC and TN; simple coefficients of determination (r2) were 0.81 and 0.69, respectively. CaCO3 was highly correlated with pH-H2O and pH-KCl; r2 values were 0.68 and 0.60, respectively. Similar correlations were obtained for pHKCl vs pH-H2O and pH-KCl vs EC, with r2 values of 0.92 and 0.70, respectively. Total nitrogen was also very highly correlated with OC (r2= 0.88). Base saturation was highly correlated with pH-KCl and pH-H2O giving r2 values of 0.62 and 0.64, respectively. When correlative relationships were carried out among parameters within individual horizons very high correlation coefficients were obtained for OC vs TN (r= 0.98 - 1.00), OC vs P-Olsen (r= 0.96 - 0.99), BS vs pH-KCl (r= 0.82 - 1.00), BS vs pH-H2O (r= 0.86 - 1.00). Most of the simple correlation coefficients obtained for EC with pH-KCl and pH-H2O were > 0.81. High correlation coefficients (0.80 - 1.00) were obtained for % clay vs total CEC for most soils studied. Regression relationships developed constitute useful predictive indices for estimating agronomic properties from existing physical and chemical data and soil survey reports of the Bale Mountain area of Ethiopia. This study has demonstrated that statistical correlation can be used to cross-check the quality of analytical data both among horizons of different soil profiles and within individual soil profiles from prior established relationships
