Site 2 represents field or catena scale (i+1) with a size of 2.73-ha located on the Agricultural Research Station West Madison, University of Wisconsin-Madison. Soil data were collected with a profile cone penetrometer and soil cores and comprised penetration resistance, texture, bulk density and water content. Data were collected on a 10-m grid (total number of sampling points: 273) where penetration data were collected vertically continuously and soil core data (4.3-cm diameter) were randomly collected at 21 penetration locations and analyzed in 5-cm increments at specific horizons. Soil texture was analyzed by the UW Soil and Plant Analysis Laboratory (Madison, WI) based on the hydrometer method. Soil water content was derived by collecting known volumes of samples and oven drying them to obtain volumetric values. Bulk density was determined by oven drying a known volume of soil and presented on dry weight basis. The site was mapped as fine-loamy, mixed, mesic Typic Argiudolls. Land use on this site was alfalfa (Medicago sativa) for the past 3 years.
A Trimble 4600 LS differential global positioning system (GPS), single frequency, dual port, with an internal 4600 LS antenna (Trimble, 1996; Sunnyvale, CA) was used to georeference sampling locations. The GPS unit was also used to conduct a kinematic survey for the study site to derive a DEM with 1-m grid size (vertical resolution error +/- 8 cm). Elevations ranged from 321.3 to 329.6 m above sea level.