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IV. Seeding and Management of Amendment-Treated Spoil

IV. Seeding and Management of Amendment-Treated Spoil

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390



P. SUTTON AND W. A. DICK



B. MULCHES



Mulches serve as a soil protectant and enhance plant establishment (Kay,

1978). The soil is protected by reducing raindrop impact, by reducing water



flow and soil movement by trapping sediment on the sites, and by increasing

water infiltration. Mulches enhance plant establishment by holding seed

and fertilizer in place, retaining moisture, preventing crusting, and modifying temperatures of the soil.

The type and rate of amendment, the depth of mixing, and the time of

seeding all influence the need for a mulch. Hoitink et al. (1982), for example, found that when 221 tons/ha of papermill sludge were used as a soil

amendment, a mulch was not necessary for controlling erosion before

vegetation became established. Frequently, however, sites are seeded immediately after site preparation has been completed, which may not

necessarily coincide with the recommended seeding dates for the area. A

mulch will provide protection for germinating seedlings and increase the

chances for survival under less than favorable conditions.

Types of mulches available for use in land reclamation are organic

materials, rock, and chemicals. The most commonly used materials are

organic, such as residues from agricultural and wood-processing industries

(Vogel, 1981). The effectiveness of an organic mulch is roughly related to

the size and shape of the particles. Long, narrow particles are superior to

finely ground products. Rates of application for straw and hay mulches

should be 3.0-4.5 tons/ha (Vogel, 1981). If erosion control is a primary

concern, between the time of seeding and establishment of vegetation

rates as high as 8.0-10 tons/ha may be required. A crimper is commonly

used to anchor straw mulches so that they will not be removed by wind.

Recommended rates of application for bark and wood chips for most

seedlings is 85-115 m3/ha (0.95-1.3 cm deep). Where soils are droughty or

the effective rooting zone is shallow, rates of 115-190 m3/ha (1.3-1.9 cm

deep) are recommended for greater conservation of soil moisture (Vogel,

1981).



Myer et al. (1972) reported crushed stone, gravel, and wood chip mulches

showed great potential for erosion control on steep barren slopes, especially

where conventional methods might not be satisfactory. For slopes of 20%,

224-448 tons/ha of stone and gravel or 34-56 tons/ha of wood chips provided excellent soil stabilization. Erosion could be controlled much better

with 2.5 cm of stone and gravel and a slightly deeper wood chip mulch than

5.2 tons/ha of straw.

Soil stabilizers are organic and inorganic chemical products that are applied in water solutions to soil surfaces to stabilize the soil against wind and

water erosion (Vogel, 1981). These materials are designed to coat and



RECLAMATION OF ACIDIC MINED LANDS



391



penetrate the soil surface and bind the soil particles together. They are used

mainly to control only temporarily until vegetative cover is sufficiently

established to protect the site. In the humid East, the effectiveness of

chemical stabilizers is relatively short-lived compared to most mulches

(Vogel, 1981).



C. PLANT

SPECIES

Each plant species has its own growth characteristics that determine its

value in stabilizing soil. Grasses and legumes are the most effective plant

materials for controlling erosion in the early stages of reclamation. Trees

and shrubs, however, have an advantage of providing a permanent or

semipermanent cover on disturbed areas with little or no additional care and

maintenance. The selection of the proper species for planting should be

based on chemical and physical properties of the spoil, topographic influences, climate, use, and management planned. Many studies have been

conducted to determine adaptation of various plant species for revegetation

and stabilization of stripmined lands in the eastern United States (Bennett,

1971; Brown, 1971; Vogel and Berg, 1968; Ruffner, 1978; Tyner and Smith,

1945; Grandt and Lang, 1958). Listed in Table V are grasses, legumes, trees,

and shrubs that have shown some success in providing cover on abandoned

mined lands.

D. MANAGEMENT

OF SEEDED AREAS

During and after vegetation has been established on abandoned mined

lands, these areas must be managed so the vegetation will continue to provide protection against soil erosion. This may require the addition of plant

nutrients in cases in which part of the vegetative production is removed as a

crop. The need for application of limestone and fertilizer for agricultural

purposes can best be determined by soil testing.

Once trees and shrubs are established, they will survive on relatively infertile areas without the need for additional fertlizers. In reclaimed areas which

have a low soil organic matter content and which are seeded to a

grass-legume mixture, the legumes will virtually disappear from the stand

by the third or fourth year. If this occurs, application of additional N may

be required so that the grasses will maintain sufficient vigor and growth to

control soil erosion, especially on sloping areas. Also, areas to be used as

pasture for livestock should not be overgrazed as this will cause a reduction

in plant stands to the point where erosion will no longer be controlled.



392



P. SUTTON AND W. A. DICK



Table V

Seeding Rates and Lower pH Limit at Which Plant Growth Can Be Expected for Various Plant

Species Used in Establishing Vegetation on Abandoned Mined Landsf

~~~



Plant species

Common name

Grasses

Redtop

Big bluestem

Smooth bromegrass

Bermudagrass

Orchardgrass

Japanese millet

Weeping lovegrass

Ky.-31 tall fescue

Annual ryegrass

Perennial ryegrass

Deert on gu e

Switchgrass

Pearl millet

Reed canarygrass

Timothy

Rye

Foxtail millet

Indiangrass

Sorghum

Sudangrass

Winter wheat

Legumes

Crownvetch

Flatpea

Sericea lespedeza

Korean lespedeza

Common lespedeza

Kobe lespedeza

Birdsfoot trefoil

Alfalfa

Yellow sweetclover

White sweetclover

Red clover

White clover

Ladino clover



~



Seeding rate

(Wha)



Scientific name



Mixtures



Alone



Lower pH

limit



Agrosiis gigantea

Andropogon gerardi

Bromis inermis

Cynodon dactylon

Dactylsis glomeraia

Echinochloa crusgalli

var. frumeniacea

Eragrostis curvala

Festuca arundinacea

Lolium muliiflorum

Lolium perenne

Panicum clandesiinum

Panicum virgaium

Pennesetum americanum

Phalaris arundinacea

Phleum praiense

Secale cereale

Setaria iialica

Sorghastrum mufans

Sorghum bicolor

Sorghum sudanense

Triiicum aestivum



2.2-4.5

4.5-9.0

11.2-16.8

3.4-5.6

5.6-8.9

8.9-13.4



3.4-6.8

4.5-16.8

16.8-22.4

7.8-13.4

11.2-16.8

22.4-28 .O



4.0-4.5

4.5

5.O

4.0

4.5

4.5



Coronilla varea

Laihyrus sylvestris

Lespedeza cuneaia

Lespedeza siipulacea

Lespedeza siriaia

Lespedeza siriaia

var Kobe

Lotus corniculatus

Medicago saiiva

Meliloius officinalis

Melilotus arfa

Trifolium praiense

Trifolium repens

Trifolium repens



.



-



28-44.8

28-44.8

89.7-134.5



4.0

4.5

4.5

4.5

4.0

4.0-4.5

4.0-4.5

4.5

4.5-5.0

4.5

4.5

4.5

4.5-5.0

4.5-5.0

4.5



5.6-11.2

22.4

11.2-22.4

6.7-13.4

8.9-1 6.8

8.9-16.8



16.8-22.4

33.6

11.2-16.8

22.4-28.0

28.0-33.6

28.0-33.6



5.0

4.0-4.5

4.5

5.0

4.5

4.5



5.6-9.0

4.5-13.4

4.5-7.8

4.5-7.9

4.5-9.0

2.2-4.5

2.2-4.5



11.2-13.5

13.4-20.2

11.2-16.8

11.2-16.8

9.0-13.4



4.5

5.5

5.5



2.2-3.4

11.2-16.8

4.5-7.8

5.6-1 1.2

6.7-9.0

2.2-5.6

9.0-13.4

5.6-9.0

4.5-7.8

33.6-67.3

11.2-16.8

5.6-13.4

16.8-22.4

16.8-22.4

33.6-67.3



22.4-39.2

22.4-28 .O

22.4-28.0

13.5-16.8

5.6-13.4

22.4-28.0

9.0-13.4

89.7-134.5

22.4-33.6



-



-



5.5

5 .O



5.5

5.5



(continued)



393



RECLAMATION OF ACIDIC MINED LANDS



Table V (Continued)

~~



~



Seeding rate

(kg/ha)



Plant species



i=ommon name



Scientific name



Mixtures



Shrubs

Indigobushb

Silky dogwoodb

Autumn oliveb

Shrub lespedeza*

Japan lespedezab

Thunberg lespedezab

Amur honeysuckle

Morrow honeysuckle

Tatarian honeysuckle

Fragrant sumac

Shining sumac

Bristly locust



Amorpha fruticosa

Cornus arnomum

Elaeagnus umbellata

Lespedeza bicolor

Lespedeza japonica

Lespedeza thunbergii

Lonicera maackii

Lonicera morrowii

Lonicera rarorica

Rhus aromatica

Rhus capallina

Robinia fertilis



.56

Seedlings

Seedlings

1.21-3.36

1.21-3.36

1.21-3.36

Seedlings

Seedlings

Seedlings

Seedlings

Seedlings

2.24-5.61



Trees

Conifer

Eastern redcedar

Japanese larch

White spruce

Norway spruce

Jack pine

Shortleaf pine

Austrian pine

Red pine

Pitch pine

Eastern white pine

Scotch pine

Loblolly pine

Virgina pine



Juniperus virginiana

Larix leptolepis

Picea glauca

Picea abies

Pinrus banksiana

Pinus echinata

Pinus nigra

Pinus resinosa

Pinus rigida

Pinus strobus

Pinus sylvestris

Pinus taeda

Pinus virginiana



-



Acer rubrum

Acer saccharinum

Acer saccharum

Alnus glutinosa

Betula nigra

Betula pendula

Castanea mollissima

Fraxinus americana

Fraxinus pennsylvanica

Juglans nigra

Liquidambar styraciflua

Liriodendron tufipifera



-



Hardwoods

Red maple

Silver maple

Sugar maple

European black alder*

River birch

European white birch

Chinese chestnut

White ash

Green ash

Black walnut

Sweetgum

Yellow poplar



-



-



-



-



-



-



-



Alone



Lower pH

limit



4.0

4.0

4.0

4.5

4.5

4.5

5.0

5 .O

5.0

4.5

4.0

3.5



5.0

4.0-4.5

4.5-5.0

4.5-5.0

4.0

4.5

4.0

4.0-4.5

4.0

4.0

4.0

4.0

3.5-4.0



4.5

4.0

4.5

3.5-4.0

4.0

3.5-4.0

4.5

4.0

4.0

5.5

4.0

4.5



(continued)



394



P. SUTTON AND W. A. DICK

Table V (Continued)

Seeding rate

Wha)



Plant species

Common name

Hardwoods (cont.)

Osage orange

Crab apple

American sycamore

Hybrid poplars

Eastern cottonwood

Black cherry

White oak

Bur oak

Northern red oak

Black locustb



Scientific name



Mixtures



Alone



-



-



Maclura pomifera

Malus sp.

Platanus occidentalis

Populus sp.

Populus detoides

Prunus serotina

Quercus alba

Quercus macrocarpa

Quercus rubra

Robinia pseudoacacia



-



-



-



-



-



-



Lower pH

limit

4.5

4.5

4.0-4.5

4.0-4.5

4.5

4.5

5.0

4.0

4.0

4.0



Trom Vogel(l981).

hitrogen fixers.



V.



CHANGES IN SOIL PROPERTIES AS AFFECTED

BY ADDITION OF AMENDMENTS



A. PHYSICAL

Covering toxic spoil with topsoil results in a medium for plant growth

that is very similar to that of the applied topsoil. However, because of the

discontinuitybetween the topsoil and spoil, the behavior of water in the soil

will be changed compared to the soil’s location prior to its application on

the spoil. In addition, removal and placement of the topsoil can result in

compaction, which can adversely affect porosity, pore-size distribution,

and bulk density. The most important factor in predicting the amount of

soil compaction produced by soil-moving equipment is soil moisture content at time of operation (Bymes et al., 1982).

The texture of fly ash is similar to that of a silt loam (Chang et al., 1977).

When fly ash is added to a spoil the particle size distribution of the resulting

soil is modified. In the case of a fine or a course-textured spoil,the modification results in the formation of a medium-textured soil (Capp, 1978).

The silty nature and lack of stable aggregates of fly ash amendment

caused the surface of amended spoil to be susceptible to wind and water erosion (Townsend and Hodgson, 1973). Until vegetation is established, the fly

ash is highly susceptibleto being eroded and moved off the reclamation site.

Water holding capacity, as measured by available water, increased 4%

for spoils and 6% for coal mine refuse when amended with fly ash (Capp,



RECLAMATION OF ACIDIC MINED LANDS



395



1978). Fly ash applied at a rate of 336 tons/ha to acidic spoils improved

water infiltration to a depth of 122 cm (Plass and Capp, 1974). Chang et al.

(1977) noted hydraulic conductivity of soils increased with small amounts of

fly ash added but declined rapidly as fly ash volume increased.

Fly ash applied to spoil in a 1:1 ratio decreased bulk density from 1.38 to

1.15 mg/m3 (Capp and Gillmore, 1973). A decrease in bulk density of a

heavy-textured spoil is considered beneficial to plant growth. Fly ash may

also have a negative impact by being involved in a pozzolanic reaction, the

formation of a stable cement when the fly ash is wetted in the presence of

liming material. This will result in the formation of a crust and may increase

bulk density, reducing water movement and root penetration (Chang et al.,

1977; Hodgson and Townsend, 1973). If soil aggregates are formed due to a

pozzolanic reaction, then percolation of water through soil would be increased (Plass and Capp, 1974). The pozzolanic reaction was not a problem

mentioned by Capp (1978) when summerizing research conducted to investigate the use of fly ash on acidic coal mine spoils. Hodgson and Townsend (1973) reported cementation can be inhibited by adding relatively small

quantities of sewage sludge, peat, or ground straw. The pozzolanic reaction

is more likely to be a problem with unweathered fly ash.

Sewage sludge, derived from organic and inorganic matter removed from

waste water at sewage treatment plants, ameliorates physical properties of

heavy-textured spoils by improving aeration, friability, and water infiltration. Columns of spoil treated with sludge were found to absorb water

faster, and 10% more water passed through the treated columns compared

to the controls (Peterson and Gschwind, 1972). Application of 235-435

tons/ha of sewage sludge decreased the bulk density in the upper 7.5 cm of

spoil from 1.61 to 1.10-1.19 mg/m” (Peterson et al., 1979). Hinesly et al.

(1982) reported water-stable aggregates greater than 0.25 mm increased

from 12.2% in samples from untreated plots to 42.1% in spoil amended

with 896 tons/ha of sewage sludge. The available water holding capacity

was increased from 14.8 to 21.1% with this treatment.



B.



CHEMICAL



Topsoil is generally used in reclamation to provide a cover over acidic spoil.



As such the chemical properties of the reclaimed area will be identical to that of



the topsoil applied. Often it is necessary, however, to add lime or plant nutrients

to the topsoil prior to seeding to provide a more suitable medium for plant

growth. The changes in chemical properties of the topsoil which result, however, are small compared to changes in spoil when amendments such as fly ash

and sewage sludge are mixed directly into the spoil. Also, the influence of the

topsoil cover on the underlying spoil is small and occurs only slowly with time.



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