Effect of minesoil compaction on growth and yield of KY-31 tall fescue and Sericea lespedeza

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7 ICAALY
United States

Department of
Agriculture

Gar c

Forest Service

Northeastern Forest
Experiment Station

Effect of Minesoil Compaction

on Growth and Yield of KY-31
Tall Fescue and

Research Note NE-320 Sericea Lespedeza

1984

Abstract

Jerry T. Crews

Kentucky 31 tall fescue and sericea lespedeza were sown on clay and
loam minesoils that had been screened through a No. 10 sieve and
compacted to densities of 1.6, 1.8, and 2.0 g/em3, Stands of sericea
lespedeza were more difficult to establish than fescue on both minesoils and
were more susceptible than fescue to increased levels of compaction. Dry
matter yields averaged over all densities were greater on the clay than on

the loan minesoil.

Introduction

In the reclamation of surface-
mined lands, the surface of the
restored minesoil is often compac-
ted by the machinery used to trans-
port and shape the various geologic
materials. Additional compaction
may be caused by equipment used
to apply fertilizer and seed. The
surface of the restored minesoil
may be either a mix of topsoil and
overburden materials or primarily
topsoil or subsoil materials. Nat-

ural vegetation processes can seldom

restore surface cover rapidly enough
to prevent severe erosion from the
compacted surface. The bulk den-
sities of clay, clay loam, and silt
loam agricultural soils normally
range from 1.00 to as high as 1.6
g/em%, They may range from 1.20
to 1.80 g/em in sands and sandy
loam agricultural soils (Brady 1974).
This study was conducted to quan-
tify the effects of compaction (1.6
to 2.0 g/em3) on establishment,

growth, and yield of two species
commonly planted on surface-
mined areas. The effects of tex-
ture on the moisture-supplying
capacity of minesoils and on root
development patterns also were
investigated.

The study showed that sericea
lespedeza was difficult to establish
on both minesoils at all levels of
compaction, but fescue proved
comparatively easy to establish.
Results also indicate that compac-
tion of a loam minesoil to a density
of 2.0 g/em3 may not be detrimen-

tal to the growth and yield of fescue,

but such compaction may drastical-
ly reduce the growth of sericea.
Texture was found to affect the
growth of fescue and sericea signif-
icantly. The finer textured mine-
soil yielded significantly more dry
matter, averaged over all densities,
than did the coarser textured one.

Methods

One heavy and one medium
textured minesoil found in the coal
fields of eastern Kentucky were
used in the study. Neither minesoil
had developed horizon differentia-
tion at time of collection. They
were texturally classified as a clay
and aloam. The clay was collect-
ed from an orphan mine site in
Owsley County, where soils had
been mapped in the Tiisit soil series
before mining began. The loam
was collected from an orphan mine
site in Jackson County. Before
mining, soils on this site had been
mapped in the Rigley series.

Minesoils from each site were
sieved to separate the particles.
These materials measuring 1.3 em
or smaller were saved and crushed
to pass a No. 10 sieve; then each
was blended to insure textural
uniformity.

The minesoils were analyzed
for physical and chemical properties
(Table 1). Texture was determined
by the pipette method (Day 1965).
Organic carbon was determined by
the Walkley Black procedure (Allison
1965). Potassium, magnesium, and
calcium were determined using the
North Carolina extractant and
phosphorus was determined using
the Bray P! extractant (Flannery
and Markus 1971). Moisture reten-
tion characteristics were determined
for the sieved minesoils (Figure 1).
Fertilizer (15-30-15) was applied to
each blended minesoil at a rate
equivalent to 1,000 lb/acre furrow
slice (6 inch depth). Reagent grade
ealcium carbonate (CaCO.) was
applied at a rate equivalent to 2
tons agricultural grade limestone
per acre furrow Slice (6 inch depth).
The minesoils were wetted to approx-
imately 0.33 bar equivalent suction,
wrapped in polyethylene to prevent
drying, and then allowed to equili-
brate for a week.

Figure 1.—Moisture retention curves.

wal

30F

.20

me)

WATER CONTENT
QM (mass water/mass dry soil)

Loam (Jackson minesoil)
eileaee

Table 1.—Initial minesoil characteristics

Item Loam Clay
Available nutrients
Potassium 81.53 67.24
Magnesium 288.35 298.04
Caleium 395.57 207.31
Phosphorus 36.97 7.23
Texture

= percent

Sand 40.0 18.9
Silt 33.0 26.6
Clay 27.0 54.6

Other properties

pH? e 5.26 5.18
Organic matter (%) 52 1.45

8491 Soil:water

Determined by Walkley Black organie carbon

x 1.724 (Van Bremmelin factor)

Clay (Owsley minesoil)

[P= ei ia ee ee |

6 8 10

MATRIC POTENTIAL, Ym (bars)

While still moist, the minesoils
were packed in plastic greenhouse
pots that measured 16.5 em in
diameter at the bottom, 23 em
diameter at the top, and 23 em
tall. The minesoils were compacted
in 1 em increments to create columns
of near uniform densities equival-
ent to 1.6, 1.8, and 2.0 g/em3,
allowing for the moisture content
(~.30 g water/g minesoil). After
all the minesoils were compacted,
approximately 100 milliliters of
water were added to the columns
each day for 3 consecutive days
before seeding.

Kentucky 31 tall fescue (Festuca
arundinacea, Selection Ky-31) and

sericea lespedeza (Lespedeza cuneata)

were selected for the study because
these two species are commonly
used in reclaiming surface mines.
Prior to planting, seed of both
species were tested to assure via-
bility. Fifty seeds of each species
were sowed on top of the compacted
minesoil columns and covered with
dampened filter paper to prevent
desiccation.

The containers were placed on
a greenhouse bench in a randomized
complete block design with six
treatment combinations (three
density levels, two species) with
three replications. After a seedling
stand was established, pots were
watered periodically to recharge
the minesoil to near 0.33 bar suction.

Plants were allowed to experience
moderate moisture stress intermit-
tently. Natural day length was
extended by artificial light for
about 4 hours at the end of each
day during February, March, and
April. Ambient air temperature
and relative humidity were monitor-
ed for the duration of the study.

Fescue was readily established
in all pots, but sericea lespedeza
required several seedings to estab-
lish an adequate stand. Germina-
tion of sericea seed was adequate
(50%) but seedling radicles did not
make adequate growth to penetrate
the minesoil surface. An adequate
sericea stand was finally established
in all containers by mid-March.
Warmer spring temperatures and a
more friable minesoil surface may
have contributed to its eventual
establishment. After they were
well established, the fescue and
sericea seedlings were thinned to
20 plants per pot. Fescue and
sericea both were allowed to grow
for approximately 180 days after
thinning. The fescue was harvested
in late July and sericea lespedeza
was harvested in mid-October.

The tops of both sericea and fescue
were dried and weighed immediately
after harvest. Root development
could not be measured accurately
because the minesoil was so com-
pacted, but it was observed for
general growth patterns.

Results and Discussion

Growth and yield data for fescue
and sericea are shown in Table 2.
Plant height of both species gen-
erally decreased with increased
compaction. Height and growth of
sericea were more adversely affect-
ed by increased compaction than
was the growth of fescue. The
yield data for the greenhouse pots
were subjected to analysis of vari-
ance (Table 3). Treatments were
considered to be factorial sets of
density and species. A split plot
with blocks nested in textural types
was used to evaluate the data.
Texture and compaction significant-
ly influenced the final dry matter
yield of both fescue and sericea.
The interaction of texture and
compaction also proved to be signif-
icant. With one exception,
yield of both species decreased at
the highest level of compaction
(2.0 g/em3). Fescue yields on the
loam increased with increased
compaction (Table 2) even though
plant height decreased. With the
exception of sericea yield on loam,
yields of both species increased at
the first increase in compaction
(1.6 g/em3 to 1.8 g/em3). Total
dry mass production of both species
was greater on clay than on loam
(456.3 g vs. 381.2 g).

The moisture retention capabil-
ity of the loam seemed to improve
with inereasing compaction to
promote better growth of fescue.
Increased growth at the highest
density (2.0 g/em3) indicates that
water and nutrients both were
available for plant growth. The
closely packed loam reduced the
normal minesoil porosity and main-
tained moisture in a form readily
available to fescue roots. This
agrees with findings of Taylor and
Box (1961) that an increase in avail-
able soil moisture went with an
inerease in compaction on a silt
loam soil. Fescue yield decreased
at the highest level of compaction
on clay minesoil. Root development

Table 2.—Plant height and yield data

Species Compaction Plant Height? meiclon a.
Loam Clay Loam Clay

g/em3 em Timon: aay =a Qari eae
Sericea 1.6 loded 78.4 51.65 50.74
Sericea 1.8 65.4 Gile5 2Deoil 60.94
Sericea 2.0 Dies PxfoAl 16.12 23.44
Fescue 1.6 47.4 41.6 81.87 111.59
Feseue 1,8 46.9 39.6 92.01 114.63
Fesecue 2.0 40.6 41.6 114.21 91.96

8Height is averaged among three replications. Measurements
were taken immediately prior to harvest.

byield is total amount of oven-dry plant material at each
compaction rate.

Table 3.—ANOVA table for plant yield

Souree DF Ss MS Observed F
Texture (T) 1 11,773.82 WN i382 115.34*
Block in T (B) 4 408.34 102.08
Treatment (R) 5 732.78 146.56 4.98*
TR 5 11,457.68 2,291.54 77.86*
BR in T 20 588.69 29.43

*Significant at the .01 level

of fescue on both minesoils was
largely confined to the upper 3 em
of the compacted column. The
fescue roots seemingly were not
able to fully exploit the clay mine-
soil at the highest compaction
rate.

Sericea yields were reduced
drastically at the highest rate of
compaction on both minesoils.
Sericea yields were greater on the
clay than on the loam at 1.8 and
2.0 g/em3 compaction levels. The
primary roots of sericea were found
to extend the full length of the
compacted column in both mine-
soils even at the highest density.
At higher compaction rates sericea
roots may have failed to branch
sufficiently, causing water and
nutrient deficits in the plants.

The results of this study suggest
that the effects of compaction
may vary with the texture of the
reclaimed mine surface. The resist-
ance of the minesoil matrix to root
penetration is somewhat compen-
sated for by the ability of clay to

hold water and thus promote growth.

Probably, the increased water
holding potential of clay reduces
the rate of water loss with increas-

ing compaction. Also, mitigating
factors such as selection of plant
species assist in offsetting the
effects of compaction. The com-
paction of the loam soil promoted
the increased yield of fibrous shallow-
rooted fescue. Moderate compaction
may be desirable to reduce minesoil
porosity and increase the volume
water content of the coarser tex-
tured soils.

The results of greenhouse eval-
uations using containers should, of
course, be applied with caution to
field situations. Even though com-
paction may reduce or limit infiltra-
tion of water into the soil, water
added to greenhouse containers
will be retained on the soil surface
until it can soak in or evaporate,
thus supplying water to plants with
very shallow root systems. If watered
often enough, the plants will be
adequately supplied, whereas under
field conditions, water may not be
retained on compacted soils. Fine-
textured minesoils, when moderate-
ly compacted, are more subject
than coarse-textured soils to the
effects of runoff and erosion. How-
ever, moderate compaction of
coarser textured minesoils may aid
the establishment of vegetation.

xy U.S. GOVERNMENT PRINTING OFFICE: 1984—705-029/514

Literature Cited

Allison, L. E. Organic carbon. In:
C. A. Black, et al., eds. Methods
of Soil Analysis, Part 2. Agronomy
9: 1367-1378; 1965.

Brady, Nyle C. The nature and
properties of soils. 8th ed.
New York: Maemillan; 1974.
639 p.

Day, Paul R. Particle fractiona-
tion and particle-size analysis.
In: C. A. Black, et al., eds.
Methods of Soil Analysis, Part
1. Agronomy 9: 545-552; 1965.

Flannery, Roy L.; Markus, D. K.
Determination of phosphorus,
potassium, calcium, and magne-
sium in North Carolina, ammon-
ium acetate, and Bray Pj soil
extracts by autoanalyzer. In:

L. M. Walsh, et al., eds. Instru-
mental Methods for Analysis of
Soils and Plant Tissue. Madison,

WI: American Society of Agronomy;
1971: 97-112.

Taylor, S. A.; Box, J. E. Influence

of confining pressure and bulk
density on soil water matric
potential. Soil Science 91: 6-
10; 1961.

The author is a soil scientist at
the USDA Forest Service, Northeastern
Forest Experiment Station, Forestry
Sciences Laboratory in Berea,
Kentucky.

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