Veris OpticMapper Operating Instructions

Application Note: OpticMapper

Proper Mapping Techniques

1. Equipment Testing. Before mapping, perform equipment tests using electronics test

load and reference block, as recommended by Operations Manual.

2. Recognize Effects of Soil Condition. In order to generate high quality OM data, it’s
crucial to understand that field history, soil conditions, and equipment settings can affect
estimations of OM from OpticMapper measurements. The most important consideration
is soil moisture: moist soil and organic matter are both darker in color than dry soil and
low OM, which could lead to confusing and erroneous estimations of soil organic matter.
Effective OM field mapping requires consistent moisture levels—of course soils have
natural differences based on soil water-holding capacity--sand will have less moisture,
clay more. What are critical to prevent are management-related moisture
inconsistencies. These can be caused by:

a) A field having two or more moisture conditions, due to tillage, cropping, or irrigation
differences (Figure 1). To avoid these situations, treat each condition as a separate
field: map differing conditions on separate files, and make sure both conditions are
represented with calibration samples.

Figure1. Moisture variation between two fields mapped as one
b) Adjustment of OpticMapper during mapping—changing depth or down-pressure

which causes sensing depth to change (Figure 2). If in-field adjustments are required,

begin a new file and make sure both conditions are represented with calibration
samples.

Figure 2. Data shift due to adjustment of OpticMapper during mapping
c) Inconsistent row unit penetration—if the OpticMapper encounters a wheel track on

one pass and soft soil the next, there will be a different sensing depth for the two
passes. Similarly, if one pass is in bare soil and the next behind the combine pass with
thick residue, there could be a moisture difference at the sensor operating depth.
These appear as stripes in the map (Figure 3). To avoid, drive at slight angle to
predominate field traffic pattern if possible; this should eliminate streaks/strips, and will
help isolate cause if they occur (Figure 4). If not possible to map at angle, avoid wheel
tracks and heavy residue strips if possible. Move over if necessary—consistent soil
conditions are more important than consistent swath width.

Figure 3. Stripes due to inconsistent penetration or equipment issue