Relationships Between Quantitative Descriptions of Soil Structure and Basic Soil Properties.

The role and importance of soil structure has been emphasized in studies of soil water flux and solute transport. Quantitative measurements of this structure, however, have been elusive at the pedon scale.  A recently developed method using multistripe laser triangulation (MLT) 3-D surface scanning has shown promising results towards quantifying soil structure and interpedal pores larger than 0.03 mm in width.  The goal of this work was to establish the relationship between this quantitative representation of soil structure and commonly measured soil physical properties. Five sites along a toposequence in northeastern Kansas were used in this study.  These sites represented a range of particle-size distributions (PSD), organic carbon (OC) contents, and bulk densities (BD) and were located on a summit (Pawnee Series, Fine, smectitic, mesic Oxyaquic Vertic Argiudoll), shoulder (Oska Series: fine, smectitic, mesic Vertic Argiudoll), footslope (Sharpsburg Series: fine, smectitic, mesic Typic Argiudoll), sand dune (Grinter Series: mixed, mesic Lamellic Udipsamment) and floodplain (Rossville Series: fine-silty, mixed, superactive, mesic Cumulic Hapludoll).  Soil pits were dug with a backhoe and profiles cleaned using 1,1–difluoroethane, which removed artifacts from the excavated surface.  The profiles were allowed to dry before scanning to reveal prominent structures and open interpedal pores.  Scans were conducted at night to remove interference from ambient light. Relationships between quantitative metrics of soil structure derived from MLT scanning, PSD, OC, and BD will be presented and discussed.