Roadside Revegetation

IMPLEMENTATION GUIDES
Inset 10-2 | Contract specifications for a winged subsoiler
A winged subsoiler consists of a self-drafting, winged subsoiler on a dolly mount, sized for
use with a D-7 tractor. The unit consists of three winged ripper tines capable of extending
12 to 34 inches below the draw bar. Wings shall be at least 20 inches wide with a 2 inch
lift of the wings from horizontal. Tines shall have an individual tripping mechanism
that automatically resets; tine spacing must be adjustable and individual tines must be
removable. Various wing patterns must be available and easily interchangeable. Implement
must be capable of achieving maximum fracture of compacted soils (minimum 24 inches)
in one pass (Adapted from Wenatchee National Forest contract specifications).
A. Single tine
0
1’
2’
C. Three tines
0
1’
2’
B. Single tine—too deep
Critical
Depth
Typical settings for rock ripper and winged subsoiler equipment configurations are shown in
Table 10-4. These are suggested settings and should not be applied without first monitoring
the results of the equipment on the project soils. The most direct method for monitoring soil
shatter is to measure the depth to the compacted soil with a soil penetrometer or shovel (see
Section 5.3.1.1, Soil Structure – How to Assess). Immediately after a pass is made with the tillage
equipment, the penetrometer is pushed into the soil and the depth to the compacted layer is
recorded. Measurements are taken every 6 inches across a small transect perpendicular to the
direction of the tractor and spanning the width of the tillage disturbance. Plotting the depths
to compaction on graph paper gives a cross-section of the shattering pattern (Figure 10-9 is
an example of plotting soilshatter). If the shattering pattern is inadequate, adjustments can
be made to the tine depth, tine spacing, and angle of the wing. If these adjustments fail to
increase soil shatter, a second and even third pass by the ripper or winged subsoiler should
be considered. Successive passes should be made at 45 to 90° angles from the first pass to
achieve the greatest benefit.
Table 10.4 | Recommended design features for some tillage equipment
Item Implement Feature
Recommended Design
Disk
harrow
Brush
blade
Rock
rippers
Wings
of
subsoilers
Disk diameter
Number of disks
Average disk weight
Disk arrangement
Max slope (cross slope travel)
Max slope (down slope travel)
Tine spacing
Tine depth
Max slope (cross slope travel)
Max slope (down slope travel)
Tine spacing
Ripping depth
Number of tines
Max slope (cross slope travel)
Max slope (down slope travel)
Ripping depth
40 - 50 in.
6 -12
>1,800 lbs
Offset gangs, independent disks