Limitations of Section Control

There are limitations of Section Control to be aware of.

GPS Accuracy Can Cause Map and Boundary Shifts

Boundary and coverage map location are based off an initial reference point. All other mapped points within the coverage map are positioned relative to this reference point.

On start-up, system checks for existing coverage map for current field. If there is existing coverage for current field, Section Control uses original reference point from existing coverage map. If there is no existing coverage for current field, then system checks for boundary for current field. If there is a boundary, Section Control utilizes center of field boundary as reference point. If there is no boundary, a reference point is created with first recorded point for current field.

Poor GPS accuracy can affect boundaries and coverage maps. It is critical to have good GPS accuracy when using Section Control. If reference point for a Section Control boundary or coverage map is created with poor GPS, boundary and coverage map issues (gaps, overlaps, or shifts) occur as GPS accuracy increases over time.

The same issues could be seen during field operation when shading, low satellite availability, or loss of signal are experienced. To minimize a map or boundary shift, good GPS accuracy is needed, especially when establishing reference point. Having Optimize Shading checked helps prevent errors due to drastic signal level change.

Coverage Map and Actual Product Application Shows Gaps the Full Width of Boom or Implement

If the coverage map and product application shows small gaps within the full width of the boom or implement when exiting headlands or other previous coverage with Section control, do the following checks.

1. Use latest version of GreenStar™ 3 2630 Display software. This software ensures the most recent features and enhancements can be utilized.
2. Verify driving habits.
   • Slowing down when entering headlands and rapidly accelerating when exiting headlands increases severity of small gaps in coverage map. Section Control looks at speed of machine and turn on and off times to determine when to start and stop applying and painting coverage map. If machine changes speed during this time period, map and product application may not start or stop at correct time. It is important that speed remains constant when entering and exiting headlands.

     Turning around in headland at 13 km/h (8 mph), with a turn on time of 2 sec., machine travels approximately 7.2 m (23.5 ft.) at 13 km/h (8 mph) in 2 seconds. If operator accelerates during this time, machine covers this distance in less than 2 seconds. This causes delayed product application and mapping resulting in a gap.

   • The type of end turns driven can affect Section Control as well. The software can predict future position of the boom relatively well during 180 degree turns, but not during light bulb turns. If light bulb turns are made, skips in the coverage map may be more severe when exiting headlands.
3. If gaps are still in coverage map, but product application is physically correct, turn on and off times and overlap settings may not be set correctly. Reference Turn On or Off Settings and Overlap Settings sections for adjustments.
4. If multiple operations are being carried out simultaneously (for example, planting and applying fertilizer), verify the following settings to prevent gaps in the coverage map.
   • Ensure section setup is similar across all operations. For example, if planting and applying fertilizer simultaneously and using John Deere Section control for both operations, ensure both operations are configured with the same number of sections. If planter system has six sections, configure fertilizer system to have six sections.
   • Adjusting Percent Overlap in Section Control Overlap Settings could also reduce gap issues in multiple operation scenarios. The appropriate percent overlap depends on section configurations for each operation.

Prescriptions

When utilizing prescriptions, Section Control commands sections off in zero rate prescription areas.