Roadside Revegetation

PLANNING PHASE TWO: ASSESS SITE
Mitigating for Low Nutrients
Topsoil
Salvaging and reapplying topsoil are important for restoring nutrients to pre-construction
levels, especially on sensitive soils (e.g., serpentine and granitic soils). The depth to apply
topsoil should be at levels found in undisturbed reference sites or pre-construction soils, or
can be calculated by methods described in Figure 10.25 in Section 10.1.4, Topsoil.
Compost
Incorporating composts is a good method for increasing nutrients to pre-disturbance levels.
Determining which type of compost to select and how much to apply is discussed in Section
10.1.5, Organic Matter Amendments.
Fertilizers
As discussed in Section 5.5.3, Soil Nitrogen and Carbon, fertilizers should be used within an
overall nutrient strategy. See Section 10.1.1, Fertilizers, for a discussion on application methods,
fertilizer types, timing, and other important aspects of fertilization.
Biosolids
Biosolids are rich in nutrients. If sources are available and transportation economical, this is a
good way to add nutrients to disturbed sites.
5.5.5 PH AND SALTS
pH is the measurement of soil acidity or alkalinity based on a logarithmic scale of 0 to 14.
Soils with pH values below 7 are acidic, and those above 7 are basic. Basic soils have high
amounts of bases (positively charged ions), such as calcium, magnesium, potassium, sodium,
and phosphates. Basic soils have developed under arid and semi-arid climates and are found
throughout the Basin and Range, Colorado Plateau, and portions of the Great Plains. Acidic
soils have formed in wetter climates, where the continued movement of water through the
soil profile has leached the bases from the soil. Acidic soils are common in the eastern United
States, the coast range and mountains of the Pacific Northwest, and the Gulf states (Figure
5-36). Topsoils are typically more neutral when compared to underlying subsoil, whether the
soils are acidic or basic. In some cases, the topsoil buffers the plant root systems from the
underlying, inhospitable subsoil conditions. When topsoils are removed during construction,
Figure 5-36 | Soil pH levels across the US
The soils of the United States have a range of
soil pH values, from less than 5.0 to greater than
8.0. Very basic soils (high pH) are widespread
in areas of the United States that receive low
rainfall. Acidic soils (low pH) occur in areas of
very old soils common in the eastern United
States or in areas of high rainfall common to
the Pacific Northwest (http://www.bonap.
org/2008_Soil/pH20110321.png).
Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat
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