Representative Elementary Volume as a Function of Land Uses and Soil Processes Based on 3D Pore System Analysis

Representative elementary volume (REV) is required for representative measurements of soil physical properties. However, questions may arise whether REV depends on how the soil structure is modified or whether processes in the soil affect REV. Here, we explore REV dependence for contrasting land uses (conventional tillage, no-tillage, and minimum tillage) and applying wetting and drying (W-D) cycles. The effect of different subvolume selection schemes (cube and core) on REV was also investigated. For this study, high-resolution three-dimensional images obtained using the X-ray Computed Tomography (XCT) technique were analyzed. The micromorphological properties measured were porosity (P), fractal dimension (FD), degree of anisotropy (DA), and pore connectivity (C). The results show that REV depends mainly on the land uses for P and C (both selection schemes). The core method showed lower REV due to the larger volume analyzed than that in the cube method. It was not possible to define a REV for DA. The REV obtained using the cube method was more sensitive to changes in the scale of analysis, showing an increasing trend with applied W-D cycles for P and FD. Our results indicate that REV cannot be considered static since land uses and processes influence it.