Roadside Revegetation

IMPLEMENTATION GUIDES
Table 10.3 | Types of tillage and equipment
The appropriate tillage equipment for the project depends on project objectives.
Shattering Mixing Imprinting
Objectives
Rippers & subsoilers
Disks, plows, excavator
attachments
Dixon imprinter, excavator
attachments, trackwalking
Loosen compacted soil Good Good Poor
Incorporate amendments Poor Good Poor
Roughen surface Good Good Good
to recover its original bulk density (Wert and Thomas 1981; Froehlich and others 1983). In a
review of tillage projects on rangeland soils, Gifford (1975) found that deep tillage greatly
reduced runoff, while shallow tillage had little effect.
Tillage alone will not return a soil to its original bulk density or hydrologic function (Figure
10-7), nor will the effects of tillage last indefinitely, especially in non-cohesive soils (Onstad
and others 1984). There are many factors that affect the return to bulk densities and infiltration
rates typical of undisturbed reference sites. These include the type of tillage equipment used,
penetration depth, soil moisture during tillage, soil texture, presence of topsoil, and organic
matter content.
There are two fundamentally different equipment designs for reducing compaction. One
design simply lifts and drops soil in place, shattering compacted soil in the process. This type
of equipment includes rock rippers, subsoilers, and “winged” subsoilers. The second design
churns and mixes the soil. Equipment that falls into this category includes disk harrows, plows,
spaders, and attachments to excavators. This type of equipment can also incorporate soil
Inches per Hour
3
2
1
Granitic
Metasedimentary
1st 2nd 3rd 1st 2nd 3rd
Rainfall Event
Rainfall Event
Ripped & Mulched
Ripped
Prior to Ripping
Permeability rates for
lightly disturbed forest soils
100 year rainfall rate
Snowmelt rate
Figure 10-7 | Benefits of ripping
and mulching vary by soil type
Short-term benefits of ripping (using a winged
subsoiler) and mulching road surfaces vary by soil
type, as shown in rainfall simulation tests on sites in
northern Idaho. Granitic soils responded to ripping
and mulching with increased permeability during
the first storm, but permeability rates returned to
near pre-treatments rates with successive rainfall
events. Metamorphic soils reacted positively to
both treatments and maintained high permeability
rates after three rainfall events. Mulching
improved permeability in both soil types. In fact,
for metamorphic soils, the combination of ripping
and mulching increased permeability to rates
that were typical of lightly disturbed forest soils
(adapted from Luce 1997).
Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat
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