Water and Soil - Project Planning and Management for Ecological Restoration - page 106

Soil Considerations: “Don't Treat Your Soil Like Dirt!”
The suitability of soil cannot always be determined from visual site inspection. Problems with
soil may have their origins decades in the past. Past land uses can dramatically alter soil chemistry
and structure. More often than not, soil testing will be required to ensure that the appropriate soil
chemistry is present. It is worth the time and money to conduct some chemical and physical test-
ing. Disasters can be avoided by a few simple tests.
Soil is the unconsolidated mineral and organic material on the immediate surface of the earth
that serves as a natural medium for the growth of land plants. Soil is a “living system” of numer-
ous organisms that contribute to its formation and maintenance. Organisms residing in the soil
substrate are diverse and include algae, fungi, protozoa, nematodes, gastropods, arthropods, earth-
worms, and small mammals such as voles, shrews, and gophers.
Soil is composed of solids and pore space. In the soil matrix, the pore space is occupied by air
and water. Data addressing appropriate water, air, and soil composition for native vegetation are
very scarce because research in these areas for nonagricultural lands has not been a focus until
recent years. In most texts, the figures of ideal percentage of water, air, and soil are derived from
optimum agricultural land and therefore, most likely, will provide only a partial awareness of re-
quirements for your project.
Among the host of different organisms found in soil, mycorrhizae have drawn a great deal of
attention. Several companies advertise inoculant for sale, and others sell plants inoculated with
spores. The advantages of mycorrhizae are significant for most plants; however, not all plants re-
spond in the same way. Pioneering plants are able to do well without mycorrhizae (Allen 1991).
Spores are carried in the wind and by animals, especially insects. Wind has been found to be the
most significant dispersal agent for spores, which are frequently trapped by existing plants. Dis-
turbed soil will have spores, but the network of fungi hyphae may no longer function efficiently.
Recently graded or denuded land will be devoid of mycorrhizae. Sources of inoculums can be
found in undisturbed native soils with native vegetation. This is the best source of obtaining my-
corrhizae for your project because it will most likely contain the species indigenous to your region.
Unless your project is several hundred acres or is not adjacent to native vegetation, you likely will
not need to be concerned about providing mycorrhizae through deliberate actions of your own.
The vegetation community, the condition of the adjacent populations, and the substrate all factor
into the ability of mycorrhizae to colonize the restoration site (Harris 2009).
The chemistry of soil is diverse and reflects exposure to local conditions. Determining variations in
the concentrations of various soil constituents is not typically possible by visual inspection and thus re-
quires a series of tests. Soils occurring in intense industrial areas that had smokestack emissions often
have very low acidity and a high concentration of metals. Work in these areas requires thorough soil
testing to ensure that certain elements, typically found in small quantities, have not been increased
from the industrial activity. Agricultural lands, active or abandoned, may also have chemistry imbal-
ances resulting from the farming practices and the crops grown. Physical and chemical problems are
commonly encountered on candidate restoration sites. Either the primary cause or secondary effects
of degradation problems with the soil should be addressed prior to developing elaborate plans.