Veris Technologies OpticMapper - Application Note - Manual (Page 4)

- if not possible to map at angle, maintain soil and residue consistency for OpticMapper
row unit; avoid wheel tracks and heavy residue strips if possible.
-double back (also called skip-pass) if feasible as shown below (Figure 5); this provides
a more stringent pass-to-pass repeatability test
Figure 5. Double-back or skip-pass method
5. Sample the field using these guidelines
-use Veris SoilViewer software suggested sample locations, if possible
-if setting own points, choose minimum of 4 sample locations based on: well-structured
Optic-Mapper zones of greatest contrast (Figure 6)
-use OpticMapper point data (not contoured or smoothed maps) when selecting points,
since outliers and small areas may be masked by smoothing;
-include contrasting EC zones if possible
-distribute sampling points throughout field
-sample at a consistent depth; 0- 6” typical
-for each lab sample, collect minimum of 5 cores within 30 ft radius
-legacy grid sample data can be used, if point sampled (<50 ft radius) and
latitude/longitude are available; calibration to OM cannot typically be accomplished
using zone samples