Document 11871752

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Mineland Reclamation
in Arid Environments
Stu Bengson 2
Mine reclamation involves the establishment of a healthy, self-sustaining ecosystem from
severely altered substrate materials. Restoration of a site to the condition prior to mining
disturbance is not a practical goal due to extensive disturbance of substrate and soil surface.
Reclamation of mineland must focus on stabilization of the site and establishing conditions whereby
the evolutionary processes which are part of a natural ecosystem may begin.
Mine tailings have no soil characteristics, but will support vegetative growth if managed carefully.
Stabilization of the tailings and establishment of vegetation may be enhanced by spreading a layer
of crushed rock over the surface of the tailings, creating microhabitats suitable for plant growth.
Revegetation is faster if topsoil is available to spread over the tailings followed with hydroseeding
and mulching with prairie or native hay. Prairie hay is preferred as a ground cover because the hay
lays flatter than a straw mulch, includes seed and will last for years if properly tacked. Irrigation
must be supplied as needed. This program has yielded productive and viable ecosystems, but the
cost may range up to $25,000 per acre.
Native grasses do not fare well in projects which call for revegetation directly onto mine tailings
without a soil layer. Native grasses have evolved with native soil and native soil microorganisms,
components that are lacking in mine tailings. It is possible to use exotics to stabilize the sites,
which then allows introduction of natives. Four-legged organic soil growers, otherwise known as
cows, may be used to enhance revegetation roaming on sites where native hay or alfalfa has been
spread. The cattle work the organic material into the surface, creating microsites on the tailing
slopes. Their manure may be a source of seed, and provides germination sites and nutrients for
growth. This starts a progression of annual grasses and forbs which may be grazed off, allowing
perennials to become established.
In 1983 and 1984, reclamation of a site was begun with a topsoil spread of 6 inches over mine
tailings. Livestock was turned onto the site for six months, after which two exotics and four natives
were found. The soil surface was covered with vegetation. One factor which promoted this rapid
growth was breakage of the soil crust by the cattle, promoting seed germination and emergence.
Summarized by Linda Elliot, Botany Department, Arizona State University, Tempe AZ.
ASARCO Copper Operations, Tucson AZ