Revegetating
an area is rarely achieved with seed alone. Climate, soil conditions, budget,
and project deadlines are just a few considerations that contractors must
initially make regarding mulch and soil amendment choice as they work to make
the most of the seed they’ve selected. A requirement to use, native seed can
sometimes complicate these decisions, but native seed is usually the best choice
for long-term protection.
Mixing
seeds and their enhancing and protecting partners can and should be approached
as a science. Finding the right balance between quick groundcover and long-term
protection means placing your faith in strong, proven performers as well as the
willingness to try innovative methods that can save your project time and money.
Learning which choices are the right ones for your site can take periods of
trial and error. Several professionals recently shared their experience with
seed, mulch, and soil amendment use in the field.
Protecting
Wildlife Habitat in Wyoming
Sage-grouse
populations have been declining in Johnson County, WY, as well as across the
state as a whole for the past century. The state is undergoing a process
determining whether the bird species should be listed as endangered, says
Colleen Faber, a senior reclamation and regulatory analyst at Lance Oil &
Gas Company, which is a subsidiary of Anadarko Petroleum Corporation, based in
Gillette, WY.
 |
Photo: Anadarko Petroleum Company |
| Close-up view of the first year growth of falcate and native grass and forb species at the Wyoming site |
“We
look for opportunities like our seeding and reclamation to enhance their habitat
while also developing energy resources for our nation,” she says, citing as an
example a site in Johnson County, which included seeding a pipeline right of
way. “Our seeding was very successful and established very well within two
years, and it used species sage grouse and other wildlife and livestock species
utilize.”
A
seed mix that included western wheat, green needle, slender, thickspike, purple
prairie clover, maple grove native flax, yellow prairie coneflower, western
yarrow, and falcate alfalfa was added to the loamy-to-clay loamy soil at the
site. It was planted at a rate of just over 15 pounds of pure live seed per
acre.
Seed
choice had been determined by federal requirements. “The federal lands in this
project required only native seed—indigenous to the area, not collected from the
area,” says Faber. “We included falcata alfalfa on our private lands to enhance
the habitat for sage grouse. This project area has one of the largest sage
grouse populations in northeast Wyoming, along with mule deer and pronghorn
populations.”
Faber
described the area’s topography as challenging. “We are working with very
‘breaky’ country where the soils can change in very short distances,” she
says.
Workers
broadcast-seeded the yarrow, explains Faber, while “the remaining species were
drill seeded with a drag behind the seeder.”
Although
Lance Oil & Gas didn’t use mycorrhizal fungi or fertilizers on this project,
it has used them on others. Faber explains that on the project’s steeper slopes,
the company used Lehi, UT–based Granite Seed Company’s hydromulch to enhance
seed establishment as well as to provide erosion control. Granite also provided
the seed for the project.
“We
chose Granite Seed because of the quality and cleanness of the seed they
provide,” says Faber. She adds that although cheat grass (downy brome) had
infested the native rangeland at the project site, “our right of ways show
native species establishing and outcompeting these invasive annuals and
stabilizing our soils, while also enhancing the native range
land.”
Adding
Fungi for Performance and a New Type of Mulch for
Protection
Tourist
areas thrive on aesthetics, and this emphasis carries into their regional
roadwork. When an area needs to be revegetated following construction,
groundcover, which is on display, must be achieved inexpensively and must be
built to handle difficult situations on a long-term basis.
In
the fall of 2006, a highway located west of Sunriver, OR, was being
reconstructed, connecting Highway 97 to the Mount Bachelor ski resort. The
Sunriver to Mt. Bachelor Highway Project took place on a road that is heavily
used by members of a recreational community.
“The
road was already in, but it needed realignment to make it safer,” explains David
Steinfeld, a soil scientist with the USDA Forest Service. He works with the
Western Federal Lands Highway Division, which administers road projects adjacent
to or located on federal lands. “When roads are realigned, they often create new
road cuts and fills, which need to be restored.”
 |
Photo: David Steinfeld |
| Logs, woody shrubs, and small trees are ground into mulch and used onsite. |
Squirreltail,
Idaho fescue, mountain brome, common woolly sunflower, antelope bitterbrush,
lodgepole pine, and ponderosa pine seeds were locally collected and used at the
site. Native seeds were used, following federal
guidelines.
“We
use native plants unless there is a reason not to, and there was no reason not
to,” says Steinfeld, who served as the project manager for the revegetation of
native plants at this site. “We collected genetic material that was local to the
site. You might find something that’s five miles away, but this is seed that was
collected specifically for the project.
“The
grass and forb seeds were collected in that area and sent to our farmers, who
increased the seed. The other species were already in our local seed
stores.”
A
variety of seed mixes were used at several areas of the
site.
“We
used the tree seed at the high elevations on very tough sites where we wanted
trees but couldn’t plant them,” says Steinfeld. “We used the bitterbrush seed at
lower elevations. There were two grass seed mixes: low and high elevation. Rates
depended on the site and species mix.”
Seeds
often need encouragement to flourish. Mycorrhizal fungi were added to the seed
mixes.
“The
spores from the fungi begin to attach and affect the root system. It’s a
relationship that began millions of years ago. We use mycorrhizal fungi when
working to restore highly disturbed sites, especially if topsoils are gone and
we are working only with subsoils,” says Steinfeld. “We assume that there will
be no inoculum of mycorrhizal fungi to establish on plant roots. Since
mycorrhizae is essential for establishing most of the species we work with, we
have to apply it in a powder form to our seeds before we
sow.”
Fungi
from Mycorrhizal Applications, based in Grants Pass, OR, were purchased for use
at the site.
“Mycorrhizae
also helps restore soils by excreting organic glues called glomalin, which are
important for creating and maintaining soil structure,” explains Steinfeld. “It
is important to understand that we integrate mycorrhizal fungi into an overall
strategy of trying to create conditions for a functioning soil to develop over
time.”
Other
strategies he describes include using tillage in an effort to improve soil
structure; adding organic mulch, slash, and composts; improving soil nutrition
through the use of fertilizers and composts; and increasing slope and soil
stability.
The
site’s soils are typically deep, with a sandy, loamy texture. “The soils are
derived from a pumice parent material originating from Mount Mazama about 6,850
years ago, so they are quite young,” Steinfeld says. “In their natural state,
they have low bulk densities with nutrient levels that are in the lower ranges
for most plants.”
During
the first year, the project was hand-seeded. After seed germination, workers
applied fertilizer after the rainy season.
Workers
applied a slow-release organic fertilizer (Biosol) at the site during the second
year at a rate of approximately 1,500 to 2,000 pounds per
acre.
“The
second year, we applied fertilizer with the seed,” says Steinfeld, noting that
at this time mulch was applied over the soil to improve germination and for
surface stabilization. “Because the climate is semi-arid, the soil surface dries
out quickly in the spring, just when the seeds need to have moisture to
germinate. Without mulch, seeds dry out quickly and die. You have to have a
protection for it not to dry out for at least the next 10 to 20 days. It’s got
to be stable, and it’s got to be protected. We applied about 0.8 inch of wood
fiber mulch on the entire project, which amounted to about 100 to 120 cubic
yards per acre.”
During
the second year, the site was hydroseeded.
Steinfeld
had seen the giant piles of slash that came from the road right-of-way material,
and he decided to have mulch created from this pile of trees, shrubs, and
organic material using a large grinder. When roads are realigned or created, he
explains, soil becomes exposed that must be vegetated. Instead of burning the
organic material that’s removed to make way for the new vegetation, Steinfeld
sought to create an organic mulch to protect the seeds.
“The
challenge was that this was the first time we made mulch out of right-of-way
material,” he says, adding the material was high in carbon. “We were trying to
figure out the mulch rates and application rates.”
The
mulch was blown over about 20 acres of the site.
“The
take of the vegetation was good. I am so impressed with it, because it really
does slow down sediment,” says Steinfeld. “Then, on top of it, you get the seed
mulch. It’s a little more expensive, but you’re not in there trying to fix
things year later.”
Steinfeld
explains that his organization is working to return carbon “into highly
efficient soils,” adding that this process can take time.
“It
doesn’t create a soil instantly,” he says. But at this site, reusing organic
material already present turned a green solution into a successful
one.
Properly
Nurturing Natives
Crystal
Creek Prairie Park in Mokena, IL, is the site of a large-scale wetland
mitigation with an approximately 14-acre upland prairie buffer, according to
Tony St. Aubin, operations officer of the Crete, IL, office of JFNew, a native
seed grower and installer that also designed the project for local resident
use.
“The
park includes paved walking trails, signs, benches, and trash receptacles,” he
explains.
The
vegetation that was so crucial to the site’s survival provides a home for an
assortment of wildlife. “The site offers a great grassland and wetland birding
habitat and has seen state-listed birds,” he notes.
Careful
thought was given to seed choice for the project. Approximately 10 to 15 native
species were added to several seed mixes used on the site, including an upland
prairie mix, a mesic prairie mix, a wetland edge mix, and shallow emergent seed
mixes, says St. Aubin.
JFNew
used a variety of seed instillation techniques with the clay-loam
soil.
“The
seed was installed using a Truax drop seeder and stabilized using the Hydrostraw
StrawNet pellets,” says St. Aubin, adding that drill seeding was also used. The
area received a Plateau herbicide treatment to discourage unwanted plant growth,
and clay pellets were added to benefit the shallow emergent mix. “The pellets
were applied via broadcast application using a Cyclone
broadcaster.”
 |
Photo: Michael Amaranthus |
| Mycorrhizal fungi added to seed mixes |
Various
aspects of individual areas of the site determined the customized instillation
approach that JFNew took, says St. Aubin. “Each installation technique has
unique benefits and was used based on site-specific details such as existing
vegetation regime, hydrology, and anticipated erosion
potential.”
The
topsoil had been stripped before excavation began on the wetlands but was later
replenished. The seedbed was tilled and raked before any seeds were sown.
Because the replenished topsoil was suitable for the project, says St. Aubin,
the company didn’t add soil amendments.
“Although
no soil amendments were used during this project, JFNew did use a cover crop
with the permanent matrix seed mix to help alleviate weed pressure from
undesirable species,” he says. “The upland areas had significant issues with
nondesirable species such as teasel, crown vetch, and Canadian
thistle.”
The
company decided to take on this challenge with a long-term
approach.
“A
multi-year management plan, which includes prescribed burning, selective
herbicide application, mowing, and reseeding, has significantly decreased weed
pressure and increased native species diversity and
density.
“The
wetland areas had significant variations in hydrology levels, and JFNew has
experienced everything from severe drought to severe rains. Included in the
original design was a water control structure, Agri Drain, which has allowed us
to help manipulate hydrology and hence increase survival/persistence of native
species.”
Because
it was a large wetland mitigation project, a native buffer was required at the
site, says St. Aubin. While some projects need fast-establishing vegetation to
protect the soil from erosion, it is not a consideration on many sites where
native plants are a requirement. For some people, there is even a question as to
how local a seed species must be to an area before it can be considered a native
species of that site. St. Aubin explains how localized the seed was at the
Crystal Creek site: “Genotyping of seed has become a hot topic among the
restoration community over the past several years. Since this project was to
design and implement during 1999 through 2002, genotyping of seed was not a
controversial topic,” he says. “JFNew supplied species native to Will County,
but they may not have been propagated from local plants.”
Looking
for Long-Term Growth In a Short Growing Season
Choosing
the right soil amendments can be crucial when working at high altitudes. Seed
can dry out quickly here, as well as be assailed by strong winds. The Berthoud
Pass widening, a Colorado Department of Transportation project near Berthoud
Falls, CO, in 2000, is an example of one such project.
“The
main challenge on the project was the altitude: 10,500 feet and up to the
summit,” says Ron Dean, an estimator with Down To Earth Compliance based in
Denver, of the effort to widen US Highway 40. “The growing season was extremely
short. The average date of last frost is June 30 and average first frost is July
30. It was not uncommon to have snow and rain showers every afternoon with
severe lightning storms.”
Seed
for the project—a blend of native species of grass and forbs including western
wheat, slender wheat, Canby bluegrass, sideoats, blue grama, lupine, showy
goldeneye, and Ponderosa pine—was added at “50 pounds plus an acre,” according
to Dean. It had to be propagated at a similar altitude to the Berthoud Pass in
Rocky Mountain states to be approved for use at the highway site, he explains.
Slopes were steep, and the soil was extremely rocky. Biosol organic fertilizer
from Bowman Construction based in Denver was used to stimulate vegetative
growth.
“Biosol
was applied at 2,000 pounds per acre, humate at 1,000 pounds per acre, and
superphosphate at 100 pounds per acre,” says Dean. “The areas were hydromulched
with a ton of wood fiber and 200 pounds of tackifier. The amendments were to
establish a sustainable soil condition for the grass and
forbs.”
The
organic fertilizer is designed to provide nutrients for plants throughout their
growth cycle, improving a soil’s humus content, controlling thatch, promoting
microbes, and stimulating root development. Biosol, he explains, was selected
because it’s been used on most CDOT projects for years and the organization is
familiar with its benefits.
“Biosol
was chosen because of the success establishing grasses in the Rocky Mountain
region,” says Dean.
The
altitude wasn’t the only challenge that the workers at the site experienced.
Highway construction typically can create a treacherous job site, a site where
workers cannot afford to lose focus.
“Traffic
control was very difficult, which made seeding and mulching an adventure,” says
Dean. “The tourists did not understand that the mist from spraying hydromulch
with tack was difficult to remove from their cars, so the occasional green car
was seen limping down the pass to the car wash.”
Respecting
Runway Restrictions
The
expansion of O’Hare International Airport
in Chicago—the second busiest airport in the world, according to a recent
Airports International Council report—is both a massive and a delicate project.
Countryside Industries of Wauconda, IL, has 14 different contracts totaling more
than $2 million at the worksite, seeding thousands of acres during the next few
years. Lee Keenan, a vice president with Countryside Industries, explains the
difficulties of establishing and protecting seeded areas at one of the recently
installed airport runways.
“Any
work you’re going to do at an airport, you’re going to have challenges. There
are restricted-access areas, timing when we could have access to it, getting
people properly badged,” says Keenan, adding that the company balanced security
issues as well.
A
tall fescue seed mix was selected for the site, he says, particularly because it
establishes itself quickly and won’t attract birds, which can cause problems at
airports. Applying sod wasn’t an option, primarily because of the cost of water
to initially maintain it.
“We
seeded with brilliant seeder, and then we used a 13:25:12 slow-release
fertilizer,” says Keenan. The seeding took place July 2008 into August 2008. One
concern that workers had was that the runway needed to “go live” during the last
days of September.
Workers
applied roughly an acre of North American Green’s HydraCX2 to the
site, which has helped the vegetation establish itself. The product is composed
of straw, polymers, and reclaimed cotton plant material that is combined and
then hydraulically applied.
“The
HydraCX2 allows stabilization on the runway without using blankets
and staples, which are not allowed near a live runway of an airport,” says
Keenan.
The
vegetation will create a green appearance that holds an appeal for the millions
of travelers who will pass through the terminal, as well as prevent the erosion
that can occur at airport construction sites, bringing together beauty and functionality.