ESTABLISHMENT OF KURA AND RED CLOVER ON SOIL AND MINE SPOIL
David C. Ditsch, Michael Collins and Norman L. Taylor
Numerous benefits result from the addition of forage legumes to
livestock diets. Superior nutritive value and intake of legume forage
generally increase individual animal productivity compared with grass
alone. This is particularly important with tall fescue where dilution
of the diet with legumes can partially alleviate toxicosis associated
with endophyte fungus infected fescue (Acremonium coenophialum).
Unfortunately, short-term persistence of most legumes requires periodic
reestablishment, adding to the cost of forage production and complicating
Perennial legumes are beneficial to soil development and the
revegetation of reclaimed surface mined lands (Ditsch and Collins, 1996).
After surface mining, there is little or no organic matter in the soil and
symbiotic nitrogen (N2) fixation by legumes can provide the N to initiate
the N cycle. Persistent legumes could increase the overall level of plant
available soil N during reclamation as well as improving forage yield and
quality where the designated post-mine land use is pasture/hayland or
Kura clover (Trifolium ambiguum Bieb.) is a long-lived perennial
legume introduced from the Caucasian Region of Russia. Kura clover
closely resembles white clover but spreads vegetatively by rhizomes
(horizontal underground stems). Kura's persistence is due primarily
to it's ability to spread over substantial distances by way of rhizome
growth. Researchers have reported kura clover survival after 5 years
to be greater than white clover, red clover and alsike clover
(Trifolium hybridum L.) In 9-yr-old stands, kura clover plants had
spread an average of 23 inches, with the greatest spreading occurring
in pastures subjected to higher stocking rates (Allan and Keoghan, 1994).
Low seedling vigor has been identified as a limitation to successful
establishment of kura clover (Taylor and Henry, 1989; Caradus, 1994; Ehlke
et al., 1994). Failure to effectively inoculate kura clover seed or use of
less effective strains of rhizobia may contribute to the observed low
seedling vigor of kura clover (Strachan et al., 1994). When inoculant
rate was increased to five times the recommended rate, the percentage of
kura clover seedlings nodulated increased from less than 10% to more than
60%. Seedling density increased from less than 0.5 plants/ft2 to more than
Objectives of this study were to compare seedling growth and stand
development characteristics of kura clover with those of red clover on
soil and mine spoil and to assess the potential for improvement of kura
clover establishment by commercial seed treatments.
MATERIALS AND METHODS
Plot studies were established on a Maury silt loam (Typic hapludult)
soil on the Spindletop Research Farm near Lexington, KY and on a coal mine
spoil site in the Appalachian coal fields of eastern Kentucky, near
Quicksand. The Maury soil had a pH of 6.2, > 200 lbs/acre available P
and 281 lbs/acre of exchangable K and received no fertilization during
the term of this experiment. Mine spoil material was a mixture of sandstone
and shale with a pH of 7.9 and Mehlich III extractable P level of 7
lbs/acre and more than 500 lbs/acre of exchangeable K. This site received
158 lbs/acre P2O5 at the time of seeding.
Treatments consisted of Kura clover seed uncoated, coated, or
coated plus fungicide and red clover. Seed of Rhizo' kura clover was
obtained from the U.S.D.A. Natural Resource and Conservation Service,
Plant Materials Center in Quicksand, KY. Uncoated kura clover (K) was
inoculated with the appropriate strain of Rhizobium (LiphaTech Inc.,
Milwakee, WI) and refrigerated for 3 days prior to seeding. Portions of
the same seed lot were coated with a commerial seed treatment (Rhozo-Kote,
Celpril, Manteca, CA) (KC) and the same coating material plus a fungicide,
metalaxyl (N-(2,6-Dimethylphenyl)-N-(methoxyacetyl)-alanine methyl ester
(KCF). Both coating treatments included the peat based Rhizobium inoculum
at a rate of 0.4% w/w. Germination averaged 79, 75 and 76% for uncoated,
coated and coated kura clover plus fungicide, respectively, with not more
than 5% hard seed. Kenstar' red clover had a germination of 95%.
Plots measured 2.6 x 18 ft on the Maury soil site and 5 x 20 ft on
the mine site. Each treatment was replicated 6 times on the Maury soil and
4 times on the mine site, in a randomized complete block design. Uncoated
kura clover (K) was seeded at a rate of 12 lbs/acre using a small plot
drill with a 6 inch row spacing. Seeding rates of KC and KCF seed were
increased 1.34 and 1.44 times that of uncoated seed to account for the
weight of coating materials.
Mine spoil plots were seeded on 29 April 1994 into a seedbed
prepared by using a rotary tine tiller. An earlier seeding on 19 April
1994 on the Maury soil failed due to a series of heavy rain events during
a 2 week period after seeding, and a second seeding on the Maury soil was
made on 24 May 1994. No herbicides were used on the mine site. Methyl
bromide (bromomethane) was used over the Maury soil plot area. Red clover
shoot growth was removed twice during 1994 by clipping at a 2.5 inch
stubble height. Kura clover plots were also clipped but little biomass
was removed. Shoot growth was left unclipped on the mine spoil plots in
accordance with typical management on such sites.
Seedling density was determined by counting the number of live
seedlings in two randomly selected 1 meter (39 inches) lengths of row in
each plot. Shoot mass was determined by cutting 10-15 consecutive plants
at the soil surface from a randomly selected starting point in each plot.
Final stand density determinations and seedling mass samples were collected
on 4 and 5 May 1995 from the Maury soil and mine spoil sites, respectively.
At the same time, ten whole plants were collected from each plot by digging
to a depth of 12 inches. After washing, each plant was separated into
below-ground components, which included the root and rhizomes, crown and
shoot components. Each sample was dried at 140o F for 72 hr before
weighing. Daughter plants (new plants initiated by the original seedling)
were counted, removed, separated into shoot, crown and root components, and
dried as described above. Grazing damage by wildlife precluded sampling on
the mine spoil site.
Location effects were considered fixed and sampling date effects
were analyzed as repeated measures (SAS, 1985). Contrasts and multiple
comparison test were used to compare coated and uncoated kura clover
(K vs. KC) and to compare red clover and kura clover.
RESULTS AND DISCUSSION
Precipitation during 1994 was generally below long-term mean levels
at both locations, with deficits during 6 of the 8 months between May and
December at both locations. July precipitation was 2.4 and 1.6 inches
below the long-term mean on the soil and mine sites, respecitively. Mean
monthly air temperatures during fall and winter following seeding at the
mine site were 3.1 to 10.1o F above normal after being near normal through
September. Mean monthly temperatures averaged 3.1o F below normal during
Aug. and Sept. on the soil site but were also generally above normal otherwise.
Red clover consistently had greater stand densities than kura clover
at both location. (Fig. 1). Maximum red clover stand densities near 18
plants per ft of row at both sites occured within the first and second
sampling dates. Maximum kura clover stand densities also occured within
the first two sampling dates (2-3 weeks after planting) and ranged between
8 and 11 plants per ft of row at the Maury soil and mine site, respectively.
The stand density of 18 red clover seedling per ft of row represents
emergence of slightly more the one-half (53%) of the live seeds, based on
a 12 lbs/ac seeding rate and 95% germination. At 77% germination and the
same seeding rate, a kura clover stand density of 11 plants per ft of row
represents only 33% of the live seeds. This difference suggest that low
emergence may contribute to delayed or inadequate establishment of kura
clover compared with red clover.
By August of the seeding year, red clover stand densities on the
Maury soil site had declined sharply to about one-third of peak densities,
compared to only a 26% decline on the mine site. Differences in stand
reduction between the two sites is likely due to greater competition
imposed by the much larger red clover seedlings present on the Maury
Except for greater seedling stand densities recorded for KCF than
for K in August of the seeding year on the mine site, seed coating had
no effect on kura clover stand density (Fig. 1). Across coating treatments,
an average of 2.8 kura clover seedlings per ft of row were present at the
mine site on the last sampling date in the year of seeding. Measured 1 yr
after seeding on mine spoil, uncoated kura clover averaged 1.2 plants per
ft of row compared to 6.2 plants per ft of row for red clover (Fig. 1).
After the same time period on the Maury soil site, uncoated kura clover
had 3.1 plants per ft of row compared with 8.3 plants per ft of row for
Red clover shoot mass, measured in June and August of the seeding
year, was significantly greater than that of kura clover at both
locations (Table 1). In June, red clover on the Maury soil site
averaged 13.6 times more shoot mass that kura clover. On the same
date, red clover on the mine site had 4.1 times more shoot mass per
seedling than kura clover. Due at least in part to summer moisture
stress on the mine site, kura clover shoot mass increased from 6.6 mg
per plant in June to 10.9 mg per plant in August. During approximately
the same interval at the Maury soil site, kura clover shoot mass
increased from 8.9 to 222 mg per plant. Seed coating treatment had
no effect on kura clover seedling mass measured the year of seeding.
One year after seeding, kura clover treatments on the Maury soil
site had greater total-seedling, crown, shoot and root/rhizome masses
than those on the mine site (Fig. 2). Although red clover from the Maury
soil site also tended to have greater component and total plant masses
than that from the mine site, the difference was much less than for kura
clover. One-year-old red clover seedlings on the Maury soil site were
1.8 times heavier than those from mine spoil, but kura clover plants were
nearly 16 times heavier on the soil site.
Slow stand development may also be related to the tendency of kura
clover to partition photosynthate preferentially to root and rhizome
tissues compared with other legumes (Strachan et al., 1994). We found
that 1-year-old kura clover on the mine site contained 49 to 58% of its
total mass below ground compared with only 28% below ground for red
clover from the same site. Both species had lower proportions of their
total mass below ground on the Maury soil site than on the mine site
Two-year-old kura clover parent plants on the Maury soil site
averaged 2.4, 1.1 and 2.9 g per plant for shoot, crown and root tissue,
respectively (Fig. 3). No coating or fungicide effects were found for
kura clover plant component weights measured 2-yr after seeding. Red
clover was omitted from this sampling due to thin stands. On average,
8.9 daughter plants had been initiated on each parent plant, each with
an average of 0.37 g of shoot mass. The small mass of root tissue found
on daughter plants suggests that the parent plants may still play an
important role in daughter plant survival.
Rhizome Number and Size
Moorhead et al. (1994) measured rapid kura clover rhizome growth
on an acid, low-P soil using a strip tillage planting method. Within
5 months after seeding, 75% of kura clover plants had rhizomes averaging
0.82 inches in length. In the our study, two-year-old kura clover plants
had an average of 12.5 rhizomes per plant with average lengths of 6 inches
per rhizome (Fig. 3).
Kura clover dry matter production during the seeding year was much
less than red clover at both locations. However, red clover seedling
density declined more rapidly than kura clover at both locations during
this same period suggesting greater kura clover persistence. These data
also indicate that low kura clover dry matter yields, compared to red
clover, may be related to greater below ground growth, particularly on
mine spoil where frequent periods of moisture stress are common. In
general, seed coatings had no effect on growth and persistence of kura
clover at both locations.
Greater kura clover persistence along with the potential for
higher dry matter production over time, compared to red clover, are
encouraging results, particularly for use on reclaimed surface mined
land. However, more research is needed to identify management strategies
that increase the rate of establishment and seed mixtures that are
compatible to the slow development of kura clover.
Table 1. Shoot dry weight of kura and red clover seedlings sampled
during the year of seeding.
Location Seed coating/species June August
Mine Spoil Kura (K) 8.0 b 9.2 b
Kura-coated (KC) 6.7 b 13.8 b
Kura-coated + fungicide (KCF) 5.2 b 9.7 b
Red clover (RC) 27.1 a 83.2 a
Maury silt loam soil Kura 12.7 b 249 b
Kura-coated 5.6 b 143 b
Kura-coated + fungicide 8.5 b 273 b
Red clover 121.3 a 1901 a
Means within a column and location followed by the same letter are
not significantly different at the 0.05 level based on the LSD test.
Table 2. Plant component yields of kura and red clover one year
Location Treatment Shoot Crown Root Total
....% of Total..... lbs/ac
Mine Spoil Kura (K) 26.3 b 15.9 b 57.8 b 107.4 b
Kura-coated (KC) 30.3 b 13.6 b 56.2 b 130.4 b
Kura-coated + fungicide (KCF) 34.7 b 16.1 b 49.2 b 137.5 b
Red clover (RC) 45.4 a 26.4 a 28.3 a 2368.2 a
Maury silt Kura 42.2 b 22.2 a 35.5 a 3805.9 b
Kura-coated 42.5 c 21.3 b 36.2 bc 2008.4 c
Kura-coated + fungicide (KCF) 44.3 c 21.1 b 34.6 c 1914.6 c
Red clover (RC) 56.4 a 20.6 a 23.0 ab 5499.1 a
Means within a column followed by the same letter are not
significantly different at the 0.05 level based on the LSD test.
Means within a column and location, followed by the same letter,
are not significantly different at the 0.05 level based on the LSD test.
Allan, B.E., and J.M. Keoghan. 1994. More persistent legumes and
grasses for oversown tussock county. Proc. New Zealand Grassl.
Caradus, J.R. 1994. Frost tolerance of Trifolium species. New Zealand
J. Agric. Res. 38:157-162.
Ditsch, D.C. and M. Collins. 1996. Reclamation considerations for
pasture and haylands receiving 66 cm or more precipitation annually.
Proc. 13th Annual Meeting, American Society for surface mining and reclamation. Knoxville, TN, May 18-23, 1996.
Ehlke, N.J., C.C. Sheaffer, D.J. Vellekson, and D.R. Swanson. 1994.
Establishment of kura clover for seed or forage production. Proc.
13th Trifolium Conf., Charlottetown, Prince Edward Island, Canada,
June 22-24, 1994.
Moorhead, A.J.E., J.G.H. White, P. Jarvis, R.J. Lucas, and J.R.
Sedcol. 1994. Effect of sowing method and fertiliser application on
establishment and first season growth of Caucasian clover. Proc.
New Zealand Grassl. Assoc. 56:91-95.
Strachan, D.E., A.H. Nordmeyer, and J.G.H. White. 1994. Nutrient
storage in roots and rhizomes of hexaploid caucasian clover. Proc.
New Zealand Grassl. Assoc. 56:97-99.
Taylor, N.L., and D. Henry. 1989. Kura clover for Kentucky. University
of Kentucky Agric. Exp. Stn. Pub. AGR-141.