Table 6. Results of principal component analysis of soil properties responses to the different cropping and land-use systems in the Dura sub-catchment, northern Ethiopia.

Principal component, PC	PC1	PC2	PC3	PC4	PC5
Eigenvalue	8.50	6.48	2.24	1.61	1.13
Variance (%)	30.65	24.32	17.29	7.90	6.63
Cumulative variance (%)	30.65	54.97	72.26	80.16	86.79
Variables	Eigenvectors					Communalities
Cation exchangeable capacity	0.87	0.01	0.27	0.19	-0.20	0.96
Clay	0.75	0.07	0.17	-0.27	-0.04	0.92
Silt	0.54	0.23	-0.01	0.00	-0.34	0.85
Sand	0.40	0.14	-0.20	0.33	0.19	0.78
Soil organic carbon	0.51	0.83	-0.13	-0.02	0.03	0.93
Soil total nitrogen	0.48	0.81	-0.14	0.001	0.86	0.91
Soil structural stability index	0.31	0.79	0.52	0.09	-0.03	0.86
Dry bulk density	-0.16	-0.51	-0.78	-0.13	-0.10	0.89
Total porosity	0.16	0.50	0.78	0.13	0.10	0.89
A-horizon depth	0.13	0.37	0.76	0.06	0.07	0.87
Exchangeable Sodium	0.23	-0.28	-0.14	-0.74	-0.02	0.89
Exchangeable Sodium Percentage	0.15	-0.21	-0.12	-0.72	-0.03	0.87
Sodium adsorption ratio	-0.17	-0.23	-0.15	-0.71	-0.06	0.85
Available phosphorus	0.47	0.25	0.15	0.18	0.81	0.90
Soil pH	0.29	0.22	0.32	0.21	0.52	0.75
Exchangeable Calcium	0.58	0.20	0.12	-0.31	0.03	0.87
Exchangeable Magnesium	0.53	0.18	0.16	-0.26	0.37	0.85
Exchangeable potassium	0.55	0.15	0.24	0.17	0.45	0.87
Electrical conductivity	0.52	0.02	0.23	0.56	0.34	0.74
Sum of base forming cations	0.42	0.07	0.19	0.20	0.17	0.85
Base saturation percentage	0.20	0.16	-0.11	-0.07	0.20	0.90
Ratio of OC to TN (OC: TN)	0.50	0.34	0.22	-0.23	0.26	0.82

Underlined boldface eigenvector values corresponded to those highly weighted variables and retained in the PC.