SD, standard deviation; CV, coefficient of variation; EC, electrical conductivity; SOM, soil organic matter; CEC, cation exchange capacity; CM, coarse material; HC, hydraulic conductivity; PR, penetration resistance.

**Table 7.** Descriptive statistics of some soil properties in subsoil (0.3–0.6 cm) of study area (*n* = 115).

The K factor of 10 measurements of surface soil in the Hornos area in Spain was calculated and compared with three aspects of aggregate stability [51]. A significant correlation was found between the K factor and the percentage of particles <100 μm, which is accepted as a measure of the vulnerability of soil to erosion by overland flow.

The variables Fe, Cu, and pH were loaded in Factor 2, which were named as "soil fertility" factor. The soil fertility factor described 10.74% of the total variation and had a positive correlation with the two micronutrients (Cu and Fe). However, there was a negative relationship between soil pH and these nutrients. A research result [52] showed that the increased clay and iron (Fe) contents resulted in decreased soya bean emergence and soil strength. The eroded soils had lower infiltration rates and higher clay dispersion.

Properties Cu, EC, and CEC were loaded in Factor 3, and it was named as "soil chemistry factor". The soil chemistry factor described 9.89% of the total variation. Positive correlation occurred between Cu and CEC and between Cu and EC. Factor 4 was named as "soil-crusting factor" that included SOM and CI and described 8.37% of the total variation.

