1 Section of Biology and Environmental Science, The Faculty of Engineering and Science, Aalborg University, VBN2 Department of Chemistry and Bioscience, The Faculty of Engineering and Science, Aalborg University, VBN3 The Faculty of Engineering and Science (ENG), Aalborg University, VBN4 Department of Civil Engineering, The Faculty of Engineering and Science, Aalborg University, VBN5 Division of Water and Soil, The Faculty of Engineering and Science, Aalborg University, VBN6 Water and Environment Research Group, The Faculty of Engineering and Science, Aalborg University, VBN7 Urban Water and Environment Research Group, The Faculty of Engineering and Science, Aalborg University, VBN8 Institut for Agroøkologi - Jordfysik og Hydropedologi9 Department of Environmental Engineering10 Jordfysik og Jordressourcer11 unknown
assessment of inherent and compaction-affected soil structure characteristics
The aim of this study was to articulate the potential of medical computed tomographic (CT) scanning for analyzing soil structure (macroporosity, soil matrix density, number of macropores) and how these estimates compare with, and complement, traditional laboratory measurements (bulk density, total porosity, effective air-filled porosity, and air permeability). Undisturbed soil cores were sampled at two depths (0.35 and 0.7 m) in a long-term soil compaction experiment in southern Sweden 14 years after its establishment. Persistence of subsoil compaction was detectable by CT-estimated soil matrix density, bulk density, and total porosity. Vertical distribution of CT-estimated air-filled macroporosity between 0.25- and 0.45-m depth showed that biological activity effect on macroporosity was largest in the top of the soil columns from the compacted plots, whereas reduction of macroporosity was significant at the bottom of the same columns. This was not detectable by classical laboratory measurements. Variations in air permeability could be related to the CT-estimated number of pores but not to the CT-estimated air-filled macroporosity. Despite using a coarse resolution, the combination of visualization and traditional laboratory measurements proved valuable in identifying the persistent effects of subsoil compaction and the differences in soil structure among the two investigated subsoil layers. However, we recommend to systematically perform a sensitivity analysis to the segmentation threshold before any further analysis of CT-estimated parameters.
Soil Science, 2013, Vol 178, Issue 7, p. 359-368
X-ray computed tomography; Soil structure; Air permeability; Porosity; Subsoil compaction