Patent ID: 7446522
Filing Date: 2008-11-04
Classification: G01N

Abstract:
1. A constant contact reference wheel system comprising: a frame having a first end and a second end; a wheel structure having a rim for rolling contact with a soil surface, the wheel rotatably carried proximate the second end of the frame; a water permeable non-absorbent material extending around an outer periphery of the rim, the water permeable non-absorbent material receiving water from the rim for forming a constant contact with the soil surface; a reference cell carried by the frame; and an electrically conductive pathway extending from the water permeable non-absorbent material to the reference cell, the electrically conductive pathway is a water pathway extending from a water source to the rim, the water permeable non-absorbent material exuding water for contact with the soil surface, the reference cell being in fluid communication with the water pathway.