Thesis.Phase III A comparison of Festulolium cultivars and parental grasses for the reclamation of soil forming materials associated with opencast coal mining
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Thesis.Phase III A comparison of Festulolium cultivars and parental grasses for the reclamation of soil forming materials associated with opencast coal mining
1. Phase III: A comparison of Festulolium cultivars and parental
grasses for the reclamation of soil forming materials associated
with opencast coal mining
By
Mr John Richard Gibson
Submitted in part candidature for the degree of M.Sc., Institute of Biological,
Environmental and Rural Sciences, Aberystwyth University
2015
2. 1
DECLARATION
This work has not previously been accepted in substance for any degree and is not being
concurrently submitted in candidature for any degree.
Signed
...................................................................... (candidate)
Date ........................................................................
STATEMENT 1
This work is the result of my own investigations, except where otherwise stated.
Where *correction services have been used, the extent and nature of the correction is
clearly marked in a footnote(s).
Other sources are acknowledged (e.g. by footnotes giving explicit references).
A bibliography is appended.
Signed
..................................................................... (candidate)
Date ........................................................................
[*this refers to the extent to which the text has been corrected by others]
3. 2
STATEMENT 2
I hereby give consent for my work, if accepted, to be available for photocopying and for
inter-library loan, and for the title and summary to be made available to outside
organisations.
Signed .............................................................. (candidate)
Date ........................................................................
NB:
Candidates on whose behalf a bar on access has been approved by the University,
should use the following version of Statement 2:
I hereby give consent for my work, if accepted, to be available for photocopying and for
inter-library loans after expiry of a bar on access approved by Aberystwyth University.
Signed ............................................................... (candidate)
Date ........................................................
4. 3
ACKNOWLEDGEMENTS
This work is part-funded by the European Social Fund (ESF) through the European Union’s
Convergence programme administered by the Welsh Government.
This dissertation would not have been possible without crucial help from particular individuals.
Firstly, I would like to thank the direct support through John Scullion and his guidance
throughout. Secondly, I would like to highlight what a major part my dyslexia tutor, Alison Nash,
has had with this work and throughout my university education. Without Alison, I would have
truly struggled with academia and she has given me the tools to develop as an individual and as
a post graduate.
Throughout this dissertation there has been help from very kind individuals. Georgina Taubman
at Miller Argent has provided me with exceptional help. Georgina has been key with the
arrangements of site visits and additional help with numerous queries. Andrew Detheridge has
also been a pillar of support throughout all the Laboratory experiments and I would personally
like to thank him for his genuine kindness.
I would also like to take this opportunity to thank my family, friends and partner Rebecca Bryne,
for all their support with academia and this dissertation, which seemed a little less daunting with
your help.
5. 4
ABSTRACT
Coal extraction from opencast mining can cause considerable degradation to
landscapes, including the eradication of vegetation and severe damage to the soil
system’s physical, biological and chemical composition. Public and governmental
heightened awareness of environmental sensitivity and increasing demand for land in
the UK has increased pressures to restore land post-mining. This study investigated the
potential of cultivars as part of a grassland for reclamation of the opencast mine site at
Ffos-y-fran in South Wales. Research included the hybrid Festuloliums, (LpFg, LpFg2,
LpFm and Prior) and parental cultivars, (Ryegrasses - Aber Dart, Aber Magic and Fescues
- Bn1482 and Bf1317), upon four available restoration materials, (Soil forming material,
Weathered shale, Overburden shale and Boulder clay). The Festulolium cultivars
combine the benefical traits of Ryegrasses and Fescue parental species to potentially
create cultivars with enhanced productivity and tolerance amongst challenging abiotic
and biotic conditions on site. This study has collected data from the experimental plots
within its third year after establishment and analysed the above and below ground
development of all cultivars. Overall, the Fescue Bn1482 consistently produced the
greater herbage yields and percentage ground cover compared to all other cultivars in
the third year. The cultivar also produced a highly significant (P<0.001) greater
cumulative herbage yield for this growing period. This was contrary to previous findings
from the plots in their second year which concluded that Festuloliums created
significantly greater yield and ground cover within initial establishment. Bn1482 also
produced significantly greater (P<0.05) root mass within near surface topsoil, bar LpFg
and initial distribution trends have suggested Bn1482 has replicated this development
6. 5
at depth as well. However, this is not conclusive and there is no previous fully replicated
root data for comparison. The soil forming material available on site consistently aided
the cultivar’s above ground development throughout the three year study on the Ffos-
y-fran site. Investigations were undertaken into soil organic matter and microbial
activity, but these were inconclusive due to site specifics and inappropriate analytical
methods. At this stage of investigations, the Festuloliums and Fescue Bn1482 have
provided evidence that they could contribute to erosion mitigation and soil
rehabilitation, potentially as a mixed sward, for this reclamation project with the
utilisation of the soil forming material.
7. 6
CONTENTS
DECLARATION ............................................................................................................................. 1
ACKNOWLEDGEMENTS.............................................................................................................. 3
ABSTRACT.................................................................................................................................... 4
ABBREVIATIONS.......................................................................................................................... 9
LIST OF FIGURES ....................................................................................................................... 10
LIST OF TABLES.......................................................................................................................... 12
1.LITERATURE REVIEW............................................................................................................. 13
1.1 Introduction to reclamation.............................................................................13
1.2 Consequences of mining wasteland without restoration................................14
1.3 Restoration and reclamation definition...........................................................15
1.4 Issues affecting reclamation efforts.................................................................16
1.5 Treatments .......................................................................................................18
1.6 The use of vegetation within reclamation projects .........................................20
1.7 Other benefits of using vegetation as a reclamation tool...............................22
1.8 Grassland beneficial use within reclamation projects .....................................22
1.9 Grass species used within the commercial sector and reclamation projects..24
1.9.1 Perrenial Ryegrasss Lolium perenne .........................................................24
1.9.2 Fescue Fustuca..........................................................................................25
1.10 The breeding of grasses in the UK....................................................................25
1.11 Recent development of Festulloliums and potential benefits for reclamation
projects........................................................................................................................25
1.11.1 Festuloliums potential to provide environmental services ......................26
1.11.2 Festuloliums commercial potential...........................................................27
1.11.3 Festulolium potential as a reclamtion tool ...............................................28
1.12 Why would microbial activity be crucial for reclamation sites? ......................30
1.13 Gaps in Knowledge...........................................................................................32
1.14 Hypotheses.......................................................................................................35
2.METHODOLOGY .................................................................................................................... 36
2.1 Study site..........................................................................................................36
2.2 Miller Argents reclamation aim........................................................................37
2.3 Climate .............................................................................................................38
8. 7
2.4 Geology ...........................................................................................................40
2.5 Soil properties ..................................................................................................40
2.6 The field experiment ........................................................................................41
2.6.1 Experimental plot design ..........................................................................41
2.6.2 Grass species and plot layout....................................................................41
2.6.3 Grass species chosen.................................................................................43
2.6.4 Applied fertiliser........................................................................................45
2.6.5 Herbage collection ....................................................................................46
2.6.6 Ground cover assessment.........................................................................46
2.6.7 Soil cores ...................................................................................................47
2.6.8 Deep rooting distribution assessment......................................................47
2.7 Laboratory investigations.................................................................................49
2.7.1 Root biomass.............................................................................................49
2.7.2 Herbage dry matter...................................................................................49
2.7.3 Soil organic matter (SOM).........................................................................50
2.7.4 Soil respiration assessment.......................................................................50
2.8 Statistical analyses............................................................................................51
3.RESULTS.................................................................................................................................. 53
3.1 Herbage analyses..............................................................................................58
3.1.1 Cut One......................................................................................................58
3.1.2 Cut Two .....................................................................................................58
3.1.3 Cut Three...................................................................................................59
3.1.4 Cut Four.....................................................................................................62
3.1.5 Cut Five......................................................................................................63
3.1.6 Total Herbage............................................................................................65
3.2 Percentage coverage ..........................................................................................69
3.3 Soil Organic Matter (SOM)..................................................................................74
3.3.1 Loss of Ignition at 300 oC analyses results ...................................................74
3.3.2 Loss of Ignition at 400 oC analyses ..............................................................75
3.4 Respiration..........................................................................................................75
3.4.1 Natural state sample CO2 analyses ..............................................................75
3.4.2 Optimised moisture samples CO2 analyses .................................................76
3.5 Root mass ...........................................................................................................77
9. 8
3.6 Root distribution.................................................................................................79
4.DISCUSSION ........................................................................................................................... 81
4.1 Festulolium cultivars will create greater herbage yield and ground coverage
compared to their parental species. ...........................................................................81
4.2 Festulolium cultivars will have a greater root development within material
compared with their parental species. .......................................................................86
4.3 Festulolium cultivars will create greater SOM and an enhanced microbial activity
.....................................................................................................................................92
4.4 Materials will differ in their potential for reclamation objectives......................95
5. CONCLUSION......................................................................................................................... 98
5.1 Recommendations..........................................................................................100
5.2 Future Research..............................................................................................101
6. REFERENCE LIST………………………………………………………………………………………………103
7. APPENDIX (For appendix see disc)
7.1 Subplot designs
7.2 Raw Data
7.3 Two Way ANOVA Results
7.4 ANOVA Results
7.5 Kruskal –Wallis Test Results
7.6 Post Hoc, Tukey Results
7.7 Descriptives
7.8 Log 10 Data
7.9 Levenes Results
10. 9
ABBREVIATIONS
ANOVA Analysis of Variance
CO2 Carbon Dioxide
CV Cultivar
DMY Dry Matter Yield
G Gram
G/M2 Grams Per Metre Squared
HSG High Sugar Grass
IBERS Institute of Biology, Environmental and Rural Studies
KW Kruskal-Wallis test
PPM Parts Per Million
SD Standard Deviations
SOC Soil Organic Carbon
SOM Soil Organic Matter
Spp Species
TWA Two Way ANOVA
Var Variety
WLOI Weight lost on Ignition
11. 10
LIST OF FIGURES
Figure 1. Location of the Miller Argent site.....................................................................37
Figure 2. Aerial photograph of the Miller Argent site at Merthyr Tydfil. The photograph
was taken prior to the extraction of coal, part of the third phase of extraction.............38
Figure 3. Weather data collected from Miller Argent weather station, displaying climatic
variations and individual field experiments and applications of fertiliser. ......................39
Figure 4.Experimental plot layout and illustration of subplot divides.............................42
Figure 5. Illustration of the root distribution analyses and typical soil pit face which was
excavated alongside subplots on the circumference of the plot.....................................48
Figure 6. Total mean herbage (dry weight) collected from each group of grass cultivars
from cut two....................................................................................................................59
Figure 7. Total mean herbage (dry weight) collected from each group of grass cultivars
from cut three.. ...............................................................................................................60
Figure 8. Total mean herbage (dry weight) collected from each group soil material from
cut three..........................................................................................................................61
Figure 9.Total mean herbage (dry weight) collected from each group soil material from
cut four............................................................................................................................63
Figure 10. Total mean herbage (dry weight) collected from each group over all four
materials during cut five..................................................................................................64
Figure 11. Total mean herbage (dry weight) collected from each group of grass cultivars
over all four soil materials.. .............................................................................................66
Figure 12. Total mean herbage (dry weight) collected from each group of grass cultivars
from the soil forming material.........................................................................................67
Figure 13. Total mean herbage (dry weight) collected from each group of grass cultivars
from the overburden material.........................................................................................68
12. 11
Figure 14. Cultivars’ mean root mass weights and their percentage quantity of the20g
soil sample, representing all the materials......................................................................78
Figure 15.Cluster bars show the absolute counts of roots and the split of these
between the shallow and depth counts. ........................................................................80
Figure 16.Evidence of Bn1482 enhanced herbage and ground cover and the established
ground cover of festuloliums. The photographs were taken on the final cut in August on
the best performing material, soil forming material.. .....................................................83
Figure 17. The distribution of the roots of Bn1482 , LpFm and LpFm , on the soil forming
material. ..........................................................................................................................90
13. 12
LIST OF TABLES
Table 1.Statistical analyses procedure for each individual investigation..................................... 56
Table 2. Cultivars mean totals from each investigation. This data is the raw mean values which
was collected from the field subplots and the laboratory experiments...................................... 70
Table 3.Material mean totals from each investigation. This data is the raw mean values which
was collected from the field subplots and the laboratory experiments...................................... 72
14. 13
1. LITERATURE REVIEW
Throughout the history of man, land has been crucial for our existence and an
irreplaceable vital resource. The extraction and utilisation of Fossil-fuels and mineral
resources has recently escalated. Expansion of industrial areas, economic
developments, technological improvements and rapid growth of worldwide human
population, coupled with urbanisation, have driven this demand (Kundu & Ghose, 1997)
and installed a reliance upon them (Sheoran et al., 2010).
1.1 Introduction to reclamation
Mining has been integral to the Welsh economy throughout the nineteenth and early
part of the twentieth century, although the industry has reduced production due to a
competitive global market and financial cost of extraction through deep mining methods
(Haigh, 1992). Recently opencast mining for coal has become more prevalent
throughout Europe, due to increasing costs of importing coal and it is more economically
viable where coal seams are near to the surface (World Coal Association, 2012). This
investigation will be located at the Miller Argent site at Merthyr Tydfil, which uses this
opencast mining technique to extract coal. The coal is relatively close to the surface and
is accessible for extraction by creating large open pits and then removing the surface
material (European Commission, 2015).This process causes a magnitude of destruction
and degradation to on site soil, flora and fauna. Restoring mining wastelands can be
problematic, especially as the mining activities severely disfigure the aesthetic
landscape and disorder the pre-existing ecosystem, including the naturally occurring
vegetation, nutrient cycles, soil profiles, and microbial communities (Kundu & Ghose,
15. 14
1997). Historically, the development of civilisation has seen an increase in degraded sites
due to mining operations (Bradshaw, 1983).
Regular poor husbandry of these mining sites, post extraction, has developed an
increasing emphasis for the mining industry to adopt environmentally sensitive
strategies and greater reclamation efforts (Mason & Milbourne, 2013).The
improvement to reclamation projects and public awareness of this has been crucial to
combat the increasing intolerance within society to neighbouring mining operations,
due to historic legacies of degraded land and pollution originating from these sites
(Haigh, 1993).
1.2 Consequences of mining wasteland without restoration
The process of extracting coal can disfigure landscapes, alter soil aggregation and can
further degrade soils that have potential for restoration through the removal process
and long term stockpiling. All of these detrimental processes can consequently
negatively change the site’s hydrology, nutrient availability and soil dispersal (Six et al.,
2004).
The permanent transformation of the landscape and eradication of vegetation on mine
lands consequently means surrounding environments are also threatened by an
increased runoff and erosion of soil from the site (Zhao et al., 2013). Exacerbated runoff
collects important restoration material such as fine material and nutrients, amplifying
erosion and impeding the reclamation process (Polyakv and Lal, 2004). Local climatic
conditions (e.g rainfall), soil properties and the landscape’s characteristics all contribute
to the degree of erosion and runoff. These detrimental effects crucially hamper
vegetation recovery, which means the effects can proliferate, exacerbating
16. 15
environmental degradation to the site and threatening the surrounding landscape
(Zhang et al., 2015). For this reason, it is widely covered in the literature that re-
vegetating mine wasteland is fundamental for long term stable ecological restoration
and reclamation projects (Bao et al., 2012; Drazic et al., 2012).
Sedimentation is a real issue due to the collection of soil sediment from runoff, creating
gullying effects to the land, especially if the land is left bare (Sengupta, 1993). This is a
concern in Wales, where climatic conditions include periods of prolonged, frequent and
heavy rainfall (Met Office, 2015).Erosion mitigation can include re-angling slopes by
grading/ terracing, sediment traps and re-vegetation of exposed slopes.
Another issue with runoff is the chemical quality. Water that has been in contact with
coal typically contains a moderate to high level of sulphur. Also, the exposure of pyrite
in the material to air and water can lead to oxidation, resulting in acidity issues within
the collected water .This is a common problem of coal mines and the corrosive water
has great potential to affect neighbouring aquatic life, and is generally known as acid
mine drainage (Sengupta, 1993).
1.3 Restoration and reclamation definition
The coal mining industry was privatised in 1994, which allows private companys to
extract coal with restrictions set by the government. However, companies are bound by
legal obligations and guidelines to consider the surrounding environments, local
hertiage and communities (IEA, 2013). Assessments such as “Environmental Impact
Assessments” need to be obtained to assess the degree of impact that the mining
operation will have on the site and surrounding areas. These typically include mitigation
procedures (i.e detailed reclamation projects), which are assessed by the local council
17. 16
or central governments, whether the mitigation is sufficient to limit the impact to an
acceptable level. Planning consent to extract the coal then can be given to the minning
company (DCLG, 2015). Sometimes, mining bonds are set aside for future restoration
needs, post mining extraction, so that minimal environmental standards are achieved
(IEA, 2013). The ambiguous definition of restoration is therefore crucial a problem.
Ecological restoration has no one definition and is broadly seen as the method of aiding
the recovery of the land’s ecosystem (SER, 2015). Literature suggests that “restoration”
implies that rehabilitation should include the structure and functions of an ecosystem
to the exact quality of the pre-mining ecosystem (Bradshaw, 2000). Whereas,
“Reclamation” is the typically used terminology and method, which refers to the process
which aims to restore the land into a beneficial use and meets the minimal standards
required (Cooke & Johnson, 2002). Consequently, land is restored typically for
conservation or commercial use and incorporates measures to limit the site’s effects on
the surounding environment, due to legal protection of surrounding watercourses and
‘polluter pays’ law principles (IEA, 2013). However, typically rehabilitating land into a
productive state, including some biotic function or productivity, means such targets are
limited by site-specific issues or biota. Plant growth is generally crucial to create a
sustainable nutrient cycle and microbial activity (Brown & Lugo, 1994).
1.4 Issues affecting reclamation efforts
A common fundamental problem for reclamation projects is that material is frequently
vastly biologically and physically different to the site’s original soil (Bradshaw , 1997).
Tate et al., (1987) explained that the success of reclamation of Lignite wasteland sites in
18. 17
the USA, especially when topsoil was absent, was highly depending on the rapid creation
of surface soil horizons containing large volumes of soil organic matter. Unfortunately,
replacing topsoil and recreating effective horizons is often costly in the UK, so less
favourable material which is abundant on site is frequently utilised with limited horizons
(Bradshaw, 2000). Without effective mitigation, the residual material is incapable of
supporting rapid regrowth due to undeveloped soil systems and a limited seed bank
(Wick & Daniels, 2009; Piha et al, 1995). Evidence suggests sites can self-regenerate
through colonisation and succession, but this can take 100 years and is reliant on soil
material. However, surrounding environments are left vulnerable during this period and
due to UK demand for land, this has not been a feasible option (Bradshaw, 2000).
Moreover, the stockpiling of available valuable loose material, prior to extraction, is
subject to degradation due to stripping operations, anerobic storage conditions and
pressure related issues (Li, 2006).
In mined areas of South Wales, friable shale is regularly utilised for reclamation, when
there is no available topsoil and mining has extracted deep mine spoils. However when
exposed to the surrounding environment or severely disturbed it is liable to erode
through weathering. Clay particles can be released from the breakdown of the shale,
which then will display similar traits of clay substrates and have a direct impact on the
soil’s quality due to the soil pores becoming congested. Water filtration throughout the
material, like clay, is therefore impeded which can consequently create greater soil
density, waterlogging, hamper vegetation development, increase mortality of soil
microbiota and reduce the soil’s cumulative stability (Haigh, 1992; Ibarra & Moreno de
las Heras, 2004).
19. 18
Overburden, is commonly the most abundant material on site, post mining, but again
this is not a natural substrate for vegetation establishment. Overburden is the material
above coal that needs to be removed to access the coal. Shale and overburden, both
coming from depths and from raw rock, are always deficient in nitrogen. This material
is also characterised with having typically no or unavailable forms of phosphate, calcium
and /or potassium (Coppin and Bradshaw, 1982).
Maiti and Ghose (2005) investigated the rock content of Welsh overburden on coal
wastelands, concluding that the material comprises on average 55% by mass of particles
greater than the ideal 2mm. This causes an issue with retention of water and nutients
(Nicolau, 2002).
In the absence of topsoil, soil-forming materials can be created from a mixture of onsite
quarred geological and overburden materials plus other refined minerals or organic
substances. The emphasis in this procedure, is to create an effective material base to
support the needs of vegetetation growth and form a base to start the soil forming
process (Forestry Commission, 2002).This provides reclamation projects with an
alternative to overburden and shales
1.5 Treatments
Applications of nitrogen rich fertiliser are common practice, prompting rapid plant
regrowth, but without a natural nutrient cycle then the system is heavily reliant on
repeat applications and therefore is not sustainable. Vegetation such as legumes can be
added to aid nitrogen fixation but applications of phosphorus are needed to maintain
early growth (Bradshaw, 1989). Longhurst & Connor, (1999) researched on vegetation
establishment on coal reclamation sites and stated that nitrogen and phosphorus are
20. 19
both limiting factors, especially during the initial two years. Moreover, the literature
suggests that phosphate is crucial, especially with early growth and root development
within difficult materials (McQueen & Ross, 1982; Hart & August, 1988). Previous studies
into application of fertiliser on reclamation sites in New Zealand have found that varying
volumes of applied fertiliser positively correlated with increased yield. Furthermore, the
vegetation communities changed throughout time, with ryegrass establishing quickly on
materials and fescue species generally developing slower, but becoming more dominant
(Roberts et al., 1988).
One major source of these nutrients is organic matter, hence typically application of this
is required and objectives to improve the ecosystem should include provision to provide
this naturally (Danahoe et al., 1990). Gosh et al. (1983) suggested that organic carbon
within the soils is a good indicator of fertile and healthy soils. Therefore habitats that
can sustain soil organic matter (SOM) through a sustainable carbon cycle, have potential
to create a healthy soil system (Roberts et al., 1988).
The operations of strip mining using heavy machinery, stockpiling and spreading of
material can exacerbate the detrimental effects of compaction, leading to increased
runoff and surface erosion (Thompson et al., 1987). This is because the compacted
material severely limits the ground capacity to absorb the rainfall (Haigh &
Sansom,1999). Compacted land suffers from reduced soil pores and water-stable soil
aggregates. The reduced water infiltration capability and the added density restrict the
root penetrating potential to access water and nutrients (Gerrard, 2003). For these
reasons and the altered soil structure, compacted land does not favour vegetation
growth and restricts soil organisms (Haigh, 2000; Gunwald et al., 1988). Moreover,
21. 20
compacted soils can limit the capacity of organisms within soil systems to respire, which
is liable to create an accumulation of toxic CO2 which directly affects roots and the ability
of micro-organisms to access oxygen (Osman, 2013). However, studies by Keislinga et
al., (1995) concluded that some plant species are capable of adapting their root
behaviour and morphology (reducing biomass, size and increasing distribution) to
combat compacted conditions. Modern mining practices such as ripping have alleviated
compaction caused by activities, but some compaction is generally unavoidable
(Sheoran et al., 2010).
1.6 The use of vegetation within reclamation projects
Plant growth has an essential role in the reclamation process as it directly protects from
surface soil erosion and retains fine soil particles needed for soil development. Multiple
benefits include decreasing the soil density, stabilising the pH and playing an active role
in circulating mineral nutrients and transforming them into a useable form (Bradshaw,
1997). Plants can improve physical soil properties directly (soil density, water retention
and porosity) and its structure, which directly affects filtration, stabilisation and the
availability of gases, nutrients and water (Zhang et al., 2015).
Vegetational growth is highly reliant on the plants ability to access nutrients and water.
Roots are essential to explore soils and they do this by elongating through and
displacing, soil particles. Compaction can inhibit root elongation rate due to the energy
required to overcome the soil particle’s resistance and reduced aeration, although
contact between root and soil is increased (Clark et al., 2003).
Drought conditions can futher challenge the potential for roots to penetrate material,
as soils/ material can become stronger as water content reduces (Whiteley & Dexter,
22. 21
1982). Plants have adapted their roots to their surrounding soil to maximise their ability
to obtain nutrients and penetrate soil. Studies by Whalley et al., (2005) have shown that
roots of plants can also alter water movements within soils due to creating greater soil
pores within rhizosphere areas or altering repellence.
However, roots can become sensitive to rapid changes to their surrounding
environment, including soil properties, and plant species will have varying capabilities
to cope under these pressures (Russell et al., 2013). Plant have adapted their roots to
their insitu soils by developing their own biochemicial mechanisims which create
numerous unique soil-plant systems within indigineous environments (Kabata-Pendias,
2004). It is generally unclear in the literature how plant species will react to site-specific
alterations to soil properties, especially if the material is not typical of natural top/sub
soil material.
Studies by Scholefield and Hall (1985) discovered that Ryegrass root growth was
restricted by their cap & stele diameter . Numerous other studies have found that plant
species can be capable of growing their roots into pores which are smaller than their
root diameter (Bengough & McKenzie, 1997; Scholefield & Hall, 1985). The ability of
plants to penetrate throughout the soil correlates typcially with their ability to access
water and nutrients needed for growth (Humphreys, 2011). The rooting ability of
Festuca arundinacea, a Fescue species which has a deep rooting system, especially when
compared to Ryegrass, allows more access to water resources.The structuring of soil
from the rooting system also improves the water retention, further improving the
fescue’s ability to withstrand drought conditions and adding to its chararcteristic traits
desired for reclamation projects (Humphreys, 2011; Durand et al., 2007).
23. 22
Plants also have an integral part in the aggregation process forming the soil structure,
by providing SOM. This acts as the foundation for the aggregate creation. Greater
aggregation ensures further protection of particular organic matter which is an essential
nutrient supply for plants and microbial communities (Wick & Daniels, 2009).
1.7 Other benefits of using vegetation as a reclamation tool
Vegetation can also create an economic value by becoming a productive landscape or
serve as an ecological value to the site and generally improve the aesthetic value of the
landscape (Hobbs & Norton, 1996; Wong, 2003). As mentioned before, native soil that
would support vegetation is typically degraded or lost, which is a major issue that affects
reclamation success. For vegetation cover to be successful, the reclamation
management must include careful deliberation over the vegetation chosen, referring to
the chemical, physical and biological properties of the substrate material (Sheoran et al.,
2010). The parameters of the chosen vegetation are vital, due to the challenging
environment determining the ability to establish, grow, disperse and reproduce under
harsh conditions (Barnhisel & Hower, 1997).
1.8 Grassland beneficial use within reclamation projects
The restoration team at Miller Argent site at Merthyr Tydfil, have chosen grassland as
part of their reclamation programme due to the effective ground cover provided but
also due to the rooting traits which improve stabilisation and filter surface water. Miller
Argent look to use the grasslands for commercial production as grazing and for
harvesting. The grasslands also have potential for environmental benefits which include
biodiversity through food source and habitat for fauna, above and below ground (Miller
Argent, 2015). Plantations can also be used on reclamation sites, but the Miller Argent
24. 23
site specifics meant that trees could leave the land liable to initial surface erosion
(Weetland et al., 1985) and the compaction meant there was a risk of limiting tree
growth (Forestry Research, 2015; Moffat, 2006; Kuznetsova, 2011). A relamation goal
for the project, is to be commecially viable and sustainable, but in this case trees are
liable for additional maintenace costs and limited yeild, compared to the potential that
grasslands offers (Giardina et al., 1995; Filcheva et al., 2000; Karr,2002).
A successful grassland mix and management can have numerous reclamation benefits
including; aeration, greater drainage, circulating nutrients, stabilising pH, producing soil
organic matter,encouraging microbial activity / mineralisation, forming soil aggregates,
retaining mositure and creating greater soil structure and stabilisation through rooting
systems (Richards et al., 1993).
Grassland have been widely used for reclamation in Wales due to the relatively fast
surface cover and its ability to be self-sufficent without long term additional nutirent
requirements. Grasslands offer a permanent vegetation cover which has great potential
to be self-regenerating and can be utilised for recreational, commericial productivity or
conservation, within a challenging environment (high acidity, low nutrients, limited soil
water) (Halofsky & McCormick, 2005). Re-vegetating can initially reverse the site’s
degradation by limiting surface erosion through the surface vegetation cover and
stabilising soils with their extensive root systems (Li, 2006). However, the advantageous
qualities of grass species for reclamation, such as agressive growth, are also issues due
to dominance which can hinder diversity and growth of other symbiotic species such as
legumes (Halofsky & McCormick, 2005). Legumes are advantageous to grass mixes
because of the volumes of nitrogen that can be fixed within soils. Nitrogen fixation is
25. 24
created by the associated bacterium that exists within their root nodules. Commercial
grasslands including legumes can fix several hundred kilos of nitrogen per year (Hart &
August, 1988; McQueen & Ross, 1982).
1.9 Grass species used within the commercial sector and reclamation projects
As mentioned previously, grass species have been widely utilised within commercial
recreational sectors and reclamation projects. However, the specific species used or
cultivars of that species, is dependent on the beneficial traits the individual exhibits. The
following section will describe some of the most popular species used within the Uk.
1.9.1 Perrenial Ryegrasss Lolium perenne
One of the most common and widespread native grasses found in the UK is the Perennial
Ryegrass Lolium perenne. This species is commonly used throughout UK lowlands in
arable leys and hay meadows, but it is also found in recreational areas, road verges and
rush pastures, to name a few (BSBI, 2014). This species can withstand moderate grazing
pressures, hence been widely sown in grasslands with livestock (Wildlife Trusts, 2015).
The breeding of Lolium species has centred around favourable growing conditions and
therefore these cultivars are vulnerable in less favourable conditions, such as the
uplands. Perennial Ryegrass is best suited to fertile soils, with ample moisture, but
within soils that are well drained and it thrives with additional moderate levels of
fertiliser. However, the grass can exist on poor soils due to its attribute of rapid re-
establishment (Christians, 2012).
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1.9.2 Fescue Fustuca
Another grass species used in the UK agricultural sector, is the Fescue genus (Festuca
spp.). Numerous Fescue species are utilised for their grazing qualities due to their
durability and their ability to withstand drought. A dynamic grass native to Europe,
fescues can tolerate several soil types, as well as a varied scale of light exposure and
availabiity of water, making it in diverse climates and environmental conditions across
the world. Fescues have been utilised for restoration projects because of their
commercial value for increasing productivity. They also offer good coarse ground cover
and deep rooting, which combine to both reduce surface erosion and particulate erosion
(Fribourg et al., 2009).
1.10 The breeding of grasses in the UK
Grasslands have been the UK’s prefered production of fodder for livestock and also for
recreational uses. Currently at least 75% of the UK’s agricultural land is grassland and it
is commonly the primary source of income for farmers. Consequently, the majorty of
breeding research has focused on the agronomic characteristics relating to herbage to
benefit livestock, focusing on grass production and seasonal spread attributes (Thomas
et al., 2003). Breeding has historically focused on improving nutrition and enhancing the
grasses traits (tolerance and endurance) to combat environmental pressures (Nedělník,
Macháč, & Cagaš, 2009).
1.11 Recent development of Festulloliums and potential benefits for reclamation
projects
Aberystwyth University have bred a grass with attributes of both Lolium spp. and
Festuca spp., creating Festulolium species, as a response to global demands to develop
27. 26
grass productivity and environmental services in the face of climate change. The species
are closely related grass genera, which has aided the the interbreeding of both species
(Humphreys, 2015). These species have been known to interbreed naturally within the
UK due this close relations (O’brian, et al., 1967). IBERS has focused on enhancing
popular cultivated grass yields and its efficiency of water use. Success so far has included
the significant (88%) yield enhancement of Lolium multiflorum, by incorporating
favourable drought resistent Fescue genes (Humphreys, 2011). Combining both species
offers the opportunity to increase fodder quality combined with resistance and
persistence within harsh climatic conditions. This has created a geneotype which
displays traits more tolerant to conditions predicted by changing climatic conditions,
including drought and flooding (Humphreys et al., 2003), but also suitable for
challenging environments such as coal reclamation sites.
1.11.1 Festuloliums potential to provide environmental services
Festuloliums also have the opportunity to provide other environmental services below
ground. Similiar to many grasses, the root systems of Festuloliums, due to their growth,
turnover and architecture (Humphreys, 2011), can enhance soil microbial biodiversity,
carbon sequestration, provide flood mitigation and even bioremediation. By breeding
advantage traits of parental species, festuloiliums can benefit reclamation , potentially
more than any other grass species is currently capable of. Evidence suggests that
Festuloliums could play a potential role in ecosystem rehabilitation through enhancing
soil structure and stabilisation and vegetation establishment, plus environmental
services such as carbon capture and flood mitigation (Humphreys, 2005).
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The potenital to accumulate carbon in soil from the atmosphere has gathered global
interest, as a potential approach to decreasing atmospheric CO2 (IPCC, 2007). Carbon
sequestration has been dicussed broadly in the literature, including its feasibility (Smith
et al., 2007; Schlesinger, 1990; Jenkinson et al., 1991; Juwarkar et al, 2010). It has been
suggested by Thomas et al., (1996) that vegetation has the ability to accumulate carbon
in subsurface soils. Hungate et al., (1997) explained that amplified CO2 frequently
encourages photosynthesis, consequently creating the opportunity for the terrestrial
biosphere to sequester carbon at a greater rate. Interestingly, several studies have
suggested that most plants will sequest larger volumes of carbon as a response to
greater volumes of atmospheric CO2 and consequently litter production, root exudation
and root turnover, as increased. Thus, the soil will potentially receive greater nutrient
supplements and a more enriched carbon cycle from additional plant biomass, root
development and capability to sequest more carbon. This suggests that grasslands could
not only improve reclamation sites, but also sequester carbon within a changing
atmospheric environment (Humphreys, 2011). Luo et al., (1996) extensive studies on
Californian sandstone grasslands found that the majority of grasses exhibited a positive
correlation between the plant biomass and below ground respiration, highlighting the
possibility that increased above ground growth could also indicate that there are
corresponding benefits below ground with microbial activity.
1.11.2 Festuloliums commercial potential
Field studies in Aberystwyth found that other Festulolium hybrids, L. perenne × F.
arundinacea var. glaucescens (LpFg) and L. multiflorum × F. arundinacea var.
glaucescens (LmFg) produced high yields similar to parental Rye grasses (Humphreys et
29. 28
al., 2014). However, it is expected that L. perenne × F. mairei (Lpfm) would express
greater resilience to drought and heat than LpFg and LmFg (Wang and Bughrara, 2005).
Again all three showed the high growth rate typical of Lolium and the root strength and
depth of fescues (Humphreys et al., 2014). Plant-soil interactions are yet to be fully
assessed but it is reasonable to suggest the Festuloliums are able to improve SOC
capture with additional restoration benefits such as improved microbial activity
(MacLoed et al., 2013). Therefore, in areas such as reclamation sites where yield would
be stunted due to challenging abiotic and biotic conditions, the agronomic value of the
site could be potentially boosted using these grasses (Humphreys et al., 2014).
1.11.3 Festulolium potential as a reclamtion tool
As mentioned earlier, grasslands, like most vegetation, have the ability to enhance soil
structure and rehabilitate degraded material through the morphology and physiology of
grassland root systems. Deep grass roots can directly stabilise soils, limiting erosion and
therefore aiding the recovery of damaged ecosystems. The stabilisation can also
consequently retain pollutants so that they enter water systems less easily (Jones et al.,
2011; Humphreys, 2011).
Another grass bred by IBERS, Festulolium loliaceum ‘Prior’, (L. perenne x F. pratensis),
illustrated in a hydrological field experiment its superior ability to aid soil water
retention and filtration. Compared to six other graases, including its parental species,
Festulolium loliaceum cultivatars reduced runoff by 65% whilst L. perenne only managed
30% and F. pratensis 50%. Further laboratory analyses of all cultivators used in the field
experiment, revealed that the Festulolium root growth and turn-over were the major
reason behind these results compared to the parental species (Humphreys, 2011). The
30. 29
initial rapid deep rooting of the Festulolium, is followed by significiant root degradation
at depths, creating porous and structured soil, benefitiing water rention and filtration,
which accounts for its capability to reduce runoff (Cookson, 2013). However, whether
Festulolium loliaceum ‘Prior’ would express similar results in most reclamation sites is
questionable, due to the experiment only using a clay rich soil. Also, investigations
analysing the ability of this species to reseed which resulted in highly variable results
depending on location, weather and climate (Humphreys, 2011). It appears the grass
can provide a commercial use and mitigation to flooding, but whether it is possible
within a challenging growth environment, such as a reclamation site with poor
substrate, needs to be investigated. A report by Macleod et al., (2013) explained that
the Festulolium loliaceum cultivars displayed more roots which were larger and
penetrated consistently deeper than those of L. Perenne cultivars. These characteristics
could reduce compaction by providing soil porosity, helping stabilise land, give
resistence against drought and aid establishment, all of which are challenging features
common to reclamation sites (Humphreys, et al., 2013).
Festulolium could provide SOM within challenging coal mining reclamation conditions.
Nutrients from dead plant matter above and below ground are released through
decomposition into the lower soil horizons (Gerrard, 2003). Soil organic matter from
grasses could have three vital functions within reclamation material, which other plants
could benefit from. Physically, the matter influences the structure of the soil by
stabilising, helping develop the upper horizon’s ability to retain water and it also has a
thermal quality. Biologically, it is vital as a source of energy and a reserve of nutrients
for living animals, plants and microbes. Organic matter brings resilience to soil and the
species that rely upon it (Osman, 2013). The chemical composition of soils is highly
31. 30
affected by the volume/ content of SOM. This can aid cation exchange and directly affect
the stabilisation of soil pH, which can consequently have a direct impact on the species
that can exist with soil material. Importantly, organic matter enhances the buffering
effect so fluctuations in the availability of nutrients and fluctuations in pH level are
limited. Soils are therefore better equipped to absorb more nutrients due to the organic
matter and also release them due to the cation exchange (Gerrard, 2003). All of these
functions interact in a dynamic form, which the literature suggests is not fully
understood (Bradshaw, 1983; Bradshaw , 1997; Sheoran et al., 2010).
1.12 Why would microbial activity be crucial for reclamation sites?
The material that is typically used on reclamation sites has limited biological activity. A
healthy ecosystem needs soil biota so it can sustain a natural cycle of nitrogen and
carbon, improve soil porosity and composition of CO2 and organic acids, and all of these
are crucial for plant growth (Edgerton et al., 1995). The microbial communities within
the soil have a vital role of decomposing plant material, having a symbiotic relationship
with plants allowing the uptake of phosphorus and nitrogen. Additionally, plant growth
is enhanced through microbial production of polysaccharides, which also increase soil
aggregation (Williamson and Johnson, 1991). Single celled bacteria called Rhizobia also
are integral to legumes by converting atmospheric nitrogen into a usable form of
ammonia for plants (Gil-sotre et al., 2005). The literature investigating the quality and
recovery of mine soils suggest that both organic matter and the microbial populations
should be assessed as these are key indicators to gauge soil quality and are essential for
soil recovery (Schafer et al., 1979).
32. 31
Microorganisms within the soil use the soil organic carbon energy source and therefore
the total organic carbon is crucial for productivity and fertility of the soils (Edwards et
al., 1999). Soil organic matter is a major sink of soil organic carbon , thus the amount of
SOM can directly and indirectly drive the metabolic activity of microorganisms. Field and
pot experiments by Williamson & Johnson (1991) analysed the ability of Ryegrass to
accumulate microbial biomass from fertiliser, and they found that the carbon within the
soil was the limiting factor instead of phosphrous or nitrogen. However, the
investigation did only analyse the initial year of a coal mine reclamation project
Moreover, Malik & Scullion (1998) study of UK coal mine reclamation sites found that
the total SOM and SOC, accumulated over time and within the initial year the amounts
were miminal. Ussiri et al., (2006) explains that reclaimed mine soils typically have very
low soil organic carbon due to the considerable proportion of shattered and
disintergrated rock material.
Festuloliums and other grasses, may have the ability to provide enhanced soil properties
to protect microbial populations, create stablised soils and provide the SOM and SOC
needed to stimulate the development of microbrial populations.
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1.13 Gaps in Knowledge
As the literatre review suggests, the potential benefits that grasslands could provide for
a reclamation project are vast. The vegetation cover and root systems have the
capability to limit surface erosion, increase water infiltration and then enhance soil
properties and the species that exist within it. The advanced investigations into
Festuloliums suggest that the traits of these new hybrids would make them suitable
candidates for application to reclamation of coal mine sites. However, the relationship
between the Festuloliums and the soil are still relatively unknown. In recent field
experiments cultivars of Festuloliums have displayed properties which decrease surface
runoff. Laboratory investigations have also shown they have greater dispersal of roots,
which die back, creating greater porosity and turnover of roots within the soil,
potentially improving microbial populations, SOM and consequntly the SOC within soils.
The Miller Argent site at Merthyr Tydfil that is being investigated in this study, was
previously investigated by between 2013 and 2014 (Chilver, 2014). Findings from her
investigation on the same experimental plots found that all four Festuloliums (LpFg,
LpFg2, LmFm & Prior) were capable of establishing and surviving on the reclamation
materials ( weathered shale, soil forming material, overburden shale and boulder clay).
Moreover, the Festuloliums created greater herbage compared to all parental Fescue
and Ryegrass cultivars also investigated and the soil forming material was the greatest
substrate for the total herbage yield. The study concluded that the Festulolium LpFg
created both the greatest root development and above ground biomass, compared to
all cultvars investigated. An additional greenhouse investgation using a non-destructive
imaging system was unable to correlate with field herbage and root results. The vastly
34. 33
different abiotic and biotic conditions between the field and greenhouse experiements
were concluded to be the reason for the different responses.
Chilvers’ study stated that due to field soil conditions, only one replication of soil sample
of each cultivar was obtainable from each test plot. Key findings relating to SOM and
root mass are therefore in need of further investigations. Root mass was expected to be
correlated with above ground biomass throughout all test grasses, but this was not the
case, except for LpFg.
The study was only within its initial year and as highlighted by Chilver (2014) and other
literature sources ( Sopper, 1993;Malik & Scullion, 1998), the total amount of SOM
would be slight, accumulating with time. Therefore following on from Chilver (2014)
findings, the overall investigation could benefit from an additional year and further
measurements. Also, due to the exceptional drought conditions experienced in 2014,
further field analyses of yield could provide a more accurate reflection of the cultivars
potential, especially as some grasses have differing initial establishment capabilities. As
the field experiment enters its third year, results may give a better undertanding of plant
dynamics and soil interaction after initial establishment. Another important area that
Chilver (2014) was unable to investigate, was the soil microbial population within soil
materials and whether the different cutivars had an effect on these. This is crucial for
the breakdown of dead plant litter into SOM. Therefore, further investigations into this
would provide a better understanding of the cultivars and the soil material’s ability to
maintain these populations.
Therefore, there is a need to determine if there is a relationship between the cutivars
and the different soil materials. Furthermore, whether there is a difference between the
35. 34
parental species and Festuloliums cultivars. Literature has highlighted that vegetation
and soil dynamics might change over time, so investgations into cultivars and the effects
of material on yield is also beneficial within the third year of this study. To investigate
this initially, microbial population, root distribution and mass, SOM and herbage will be
investigated. Also, the literature has highlighted that the quality of minespoils may
deteriorate through weathering. Therefore the materials will be investigated to analyse
if the materials have an effect on the cultivars and whether this agrees with Chilver’s
(2014) study. The results should provide an indication of the potential uses of
Festuloliums within reclamation projects for coal mines and the findings could be
applied to other Welsh sites.
36. 35
1.14 Hypotheses
Festulolium cultivars will create greater herbage yield and ground coverage compared
to their parental species.
Festulolium cultivars will have a greater root development within material compared
with their parental species.
Festulolium cultivars will create greater SOM and an enhanced microbial activity
Materials will differ in their potential for reclamation objectives
37. 36
2. METHODOLOGY
This study has incorporate field research from the Ffos-y-fran site, Merthyr Tydfil and
laboratory experiments on field samples at the Institute of Biological, Environmental &
Rural Sciences (IBERS), Aberystwyth University. The following section will explain the
method of investigation.
2.1 Study site
The experimental plots are located within the site managed by Miller Argent which is an
opencast coal mining project, which is jointly owned by Argent Group plc, The Miller
Group Ltd and Bernard Llewellyn LP. The Ffos-y-fran site is located north east of Merthyr
Tydfil, South Wales, UK, Grid reference: SO 09161 06092 (see Figure 1 ) and this is one
of the largest opencast coal mines in Europe. The site covers 3,500 acres, it opened in
2005 and it is expected to extract 11 million tonnes of coal over 15 years. The
reclamation of this third and final phase is part of the former East Merthyr Reclamation
Scheme and is the largest of all three.
38. 37
Figure 1. Location of the Miller Argent site
Left: Location of the site is marked with a red circle, highlighting its positon in the South
of Wales, United Kingdom. Right: Location of the Miller Argent : Phase III site and the
locality of the town Merthyr Tydfil. The right circle marks the actual site.
Photographs from Bing (2015)
2.2 Miller Argents reclamation aim
The aim of the reclamation scheme, partnered by the Welsh Development Agency, is to
restore derelict and dangerous land. The previous two phases have restored land for
residential, industrial and recreational use. The third reclamation phase aims to restore
the land for recreational use which encourages local biodiversity. See Figure 2, for the
aerial picture of the site prior to the third and final phase of extraction.
39. 38
Figure 2. Aerial photograph of the Miller Argent site at Merthyr Tydfil. The photograph
was taken prior to the extraction of coal, part of the third phase of extraction. The Red
circle highlights the location of the experimental plots, which have been investigated in
this study. Photograph from Miller Argent (2015b)
2.3 Climate
The Merthyr Tydfill climate is essentially a maritime climate, which typcially can be
characterised by mild weather but frequently wet, cloudy and windy. However, the local
uplands are prone to harsh and dramatic flucuations in weather conditions.
Temperatures generally range from 0.5oC in winter to 19.5 oC in mid summer and land
is exposed to frost on 58.7 days of the year, mostly from October to April ( see Figire 3).
The area is prone to frequent unpredictable heavy rainfall throughout the year, but the
40. 39
months of June and July can be prone to prolonged periods of drought (Met Office,
2015). This was especially the case for (Chilver, 2014). Average rainfall for the area is
1674mm (Met Office, 2015).
Figure 3. Weather data collected from Miller Argent weather station, displaying climatic
variations and individual field experiments and applications of fertiliser.
The blue bars represent the total rainfall (mm) for each month, whereas the green line
represents the mean temperature throughout the months of the 2014/2015
investigations. Also highlighted in annotation boxes are the months of which the cuts were
taken of the grass from the material plots. Furthermore, annotation boxes include when
fertiliser was applied to the plots, when soil samples were extracted (.SS.) and when
percentage coverage of grass species (.% C.) was assessed.
41. 40
2.4 Geology
The soil parent material in the site is classified as carboniferous shale and sandstone.
Drift on site is from the Palaezoic sandstone mudstone. The underlying geology has
influenced the low fertility of soil on site (Cranfield University, 2015).
2.5 Soil properties
Soils associated with this area are typically Wilcocks 1 721c, which have fine loamy thin
topsoil’s over upland clayey soils and peaty horizons. These tend to have poor
permeability and therefore are liable to waterlogging. Areas which have been restored
from the opencast mining will have similar characteristics but are classified as “Neutral
Restored Opencast 962” soils and have no peaty horizons, thinner topsoil’s and material
is often stony with fragments of coal (Cranfield University, 2015).
42. 41
2.6 The field experiment
The following section will describe in detail the field experiment
2.6.1 Experimental plot design
Four plots of materials measuring 4 metres by 6 metres, all 1 meter deep, were created
by Miller Argent in 2013, under guidance given by Aberystwyth University. Each plot
consisted of recovered material from the site and represented the available material on
the site for future restoration. These included weathered shale, soil forming material,
overburden shale and boulder clay material, all of which had been stored for an
extensive period before placing as the trail plots (Scullion, 2015; Humphreys, 2015;
Chilver, 2014). The plots were also subject to typical reclamation procedures, ripping
and cultivation, to relieve compaction and improve the filtration of water, thereby
improving the potential for plant growth and establishment (Taubman, 2015; Chilver,
2014). Using a single shank ripper, larger boulders were surfaced and removed with
mechanical cultivation, alleviating compaction and reducing stoniness (Taubman, 2015).
2.6.2 Grass species and plot layout
Each material plot, has been subdivided into 24 subplots measuring 1 metre by metre.
Every grass specie in this experiment has been replicated three times within each
material plot and each one of these has been allocated a subplot by a fully randomised
method. Refer to Figure 4, for the plot layout & design and also appendix 7.1,for the
species specific randomised design for all material plots.
43. 42
Figure 4.Experimental plot layout and illustration of subplot divides.
Top: This photograph was taken of the actual experiment at the Miller Argent site at
Merthyr Tydfil. The illustrations upon the photograph display the allocation of each
material plot: A - Weathered shale, B – Soil forming material, C – Overburden shale & D –
Boulder clay.
Bottom: The drawing design provides an impression of the subplots upon each of the four
main material plots within which individual species were sown. Each subplot measured 1
metre by 1 metre.
Photograph and illustration by Gibson (2015)
44. 43
2.6.3 Grass species chosen
The grasses allocated to the plots have been chosen due to their potential to provide a
productive crop with high yield, improve ecosystem rehabilitation, reduce surface run
off, limit erosion and enhance capability to provide environmental services to the
reclamation site. This section will provide greater detail of the grasses included.
2.6.3.1 Rye grasses – Aber Dart & Aber Magic
Since 1919, the IBERS institute have been breeding commercial grasses. One of their
great successes has been the ability to create greater sugar content in Perennial Rye
grasses, and as a consequence, enhancing meat and milk production in ruminant
species. The diploid (2x) grasses have been bred using two equal sets of chromosomes
from parent Rye grasses Lolium perenne, which has improved growth and digestibility.
The first commercial successful Rye grasses from IBERS, Aber Dart (Lp) and the recently
commercially released and developed Aber Magic (Lp), have been included in this
investigation for these traits and commercial potential. Aber Dart was the first High
Sugar Grass (HSG) to be released by IBERS. A three year field study by Farm Research in
New Zealand provided evidence that the grass was extremely persistent even amongst
harsh conditions due to its deep rooting and extensive tiller compared to 12 other
leading commercial grasses investigated (Tavendale, et al., 2006). The recent Aber Magic
has seasonal differences compared to Aber Dart: later flowering, longer dry herbage
potential and reportedly benefits from quick establishment in winter and spring
(Humphreys, 2015).
45. 44
2.6.3.2 Fescues – Tall fescue Festuca arundinacea cv.Bn1482 & Meadow fescue
Festuca pratensis cv.Bf 1317
The beneficial traits of fescues have been mentioned previously (Section 1.11.2).
Fescues have had the evolutionary ability to hybridize naturally with each other. This
has given them the ability to colonize and adapt to challenging environments, which
could give greater potential for reclamation establishment and lower mortalities
(O'brien, et al., 1967).
Festuca pratensis cv.Bf 1317 (x2), has the ability to grow in a variety of soil types,
including heavy soils and clay. However, the species benefits from fertile soils and moist
conditions. The species is able to grow throughout low ranging temperatures and
includes frost tolerance (Humphreys, 2015).
Festuca arundinacea cv.Bn1482 (Hexaploid) (x6) is a species that has naturally
hybridized with Festuca pratensis and is a cool season grass that originates from
temperate climates, but is widespread from northern Europe to central Asia and
northern Africa. The wide distribution, with varying ecological environments, suggests
the grass can tolerate a range of temperatures, soil types and moisture (Kirigwi, et al.,
2004). The species expresses drought and heat tolerance and is used throughout
America and Europe due to its proven tolerance to stresses. Previous studies at
Aberystywth University, have isolated genes within Festuca arundinacea which express
traits for drought resistance. However, the species has been criticised by the farming
community for its slow growth and establishment (Humphreys, 2015).
46. 45
2.6.3.3 Festuloliums
(LpFg - Perennial Ryegrass x Mediterranean Fescue, LpFg2 - Perennial Ryegrass x
Mediterranean Fescue (Partial hybrid), LpFm - Perennial Ryegrass x Atlas Fescue, Prior -
Perennial Ryegrass x Meadow)
The benefits and hybridization of Festuloliums and the traits that can be attributed to
them from their parental grasses have been describe previously (Section 1.10). All
Festuloliums included in this study, except for Lpfg2, are tetraploids (4x). These have two
sets of chromosomes from each parental Rye grass and Fescue. However, the Lpfg2 is
only a partial hybrid created by an introgression method, which backcrosses one
particular hybrid parent. Moreover, the Lpfg2 (Diploid) (2x) has the majority of its traits
from the Ryegrass, including its HSG traits, with only a few Fescue traits, consequently
increasing its tolerance to stresses only partially. The fescues included in the other
Festulolium mix include Mediterranean Fescue, which has traits of enhanced resistance
to drought. However, the Atlas Fescue is the most drought-resistant Fescue species
known (Humphreys, 2015).
2.6.4 Applied fertiliser
According to the studies by Chilver (2014), fertiliser was only applied to the experimental
plots after the initial 2013 seeding and once more after the first cut in 2014. This is a
low volume of fertiliser for grassland establishment in challenging abiotic conditions,
according to several sources (Humphreys (2015); Li et al., (2013)). However, Li et al.,
(2013) explained that reclamation sites have to contain lower fertiliser application
47. 46
initially due to the complication of rapid growth consuming all nutrients applied and
reducing the vegetation’s ability to become sustainable. Two more applications were
applied, once in November 2014, after the first cut and again in May 2015. The Super
Cut fertiliser used throughout this study consisted of 23 % Nitrogen, 4% Phosphate, 7%
Sulphur trioxide and 13% Potassium. This is consistent with the investigation by Chilver
(2014). Fertiliser was applied at approximately 40 g/m2 subplot.
2.6.5 Herbage collection
Clippings of all 96 subplots were collected, using a visual judgement of the best growth
within each subplot to be a representative of the species growth. Vegetation growth
was then removed above the quadrat frame, leaving the thickness of the quadrat frame
(2cm) of grass to remain. All five sets of cuts throughout the investigation were
replicated consistently but the placement of the quadrat altered within each subplots.
Entire plots were mown after harvesting
2.6.6 Ground cover assessment
The method used to assess the percentage of grass that covered the ground within each
subplot was guided by studies from Floyd & Anderson (1987) and also Scullion (2015).
The ground cover of grass in each sub plot was estimated by dividing individual plots
into 25 sections. By using this aid and a photograph to guide (from the initial estimation
of vegetation cover), the estimation hoped to be kept consistent. Grass foliage and
tillage cover of ground were incorporated into the estimations.
48. 47
2.6.7 Soil cores
As a consequence of the findings of Chilver(2014) studies, on the difficulties of extracting
soil cores in dry weather, soil cores were taken during a wet period of prolonged rainfall
in July 2015. Material cores were taken using a hammer head soil sampling auger with a
20mm outer diameter and 13mm inner diameter corer. Three locations within each sub
plot were chosen, cores were taken through the crown of the grass, as advised by
Scullion (2015). However, due to compaction, only a depth of 15cm was able to be
achieved. All samples were stored for 2 days and kept at 4oC refrigeration prior to
analysis in the lab.
2.6.8 Deep rooting distribution assessment
As a consequence of compaction, material cores deeper than 15cm were impossible.
Using a method adapted on site, sub-plots on the circumference of each material plot
were able to be assessed. Digging a 20cm by 45cm hole alongside the best growth grass
on the available subplots, gave an indication of root distribution at the depths exposed.
Roots were recorded at 5, 10, 15, 25 and 35 cm depths (refer to figure 5). Unfortunately,
this was only able to be replicated once on each material for each species, at best. Data
for some species is absent, due to not being allocated a subplot on the circumference of
that plot.
It is acknowledged that this will have excluded rooting behaviours of the grasses within
non- exposed areas and that this is only a small sample to provide an indication of root
behaviour at depths.
49. 48
Figure 5. Illustration of the root distribution analyses and typical soil pit face which was
excavated alongside subplots on the circumference of the plot.
The illustrations on the photo, express the depths at which root counts were recorded if
they crossed this line.
Photograph and illustration by Gibson (2015)
50. 49
2.7 Laboratory investigations
The following section will describe the laboratory investigations.
2.7.1 Root biomass
After all visual herbage and dry litter were extracted from the soil samples, a 2mm sieve
was used to extract stones from the samples. After trialling root extraction time periods
(2, 4, 6, 8 minutes), 4 minutes was determined the most justified allocation of time to
extract roots from all samples respectively. This was concluded appropriate due to the
majority of roots being removed in all test materials and the researcher’s available time
for root extraction. The method for root extraction and biomass assessment was guided
by Scullion (2015) and Benomar et al., (2013). Using tweezers, roots were removed from
each sample and excess soil removed using distilled water with gentle washing over a
600 μm diameter pore size sieve. All roots were placed within pre-weighed labelled
pyrex test tubes, then subjected to 72 hours drying at 70oC in an air forced oven and
then re-weighed. All fine soils and stones were also dried and weighed.
2.7.2 Herbage dry matter
All samples were placed into individual paper bags and were dried at 70oC for 72 hours
in an air forced oven. Dry weight was recorded.
51. 50
2.7.3 Soil organic matter (SOM)
The weight loss-on-ignition (WLOI) method was used to analyse the amount of SOM
within soil samples. This method is widely used and accepted (Salehi, et al., 2011;
Scullion, 2015, ,Yerokun, et al., 2007) as a reliable procedure to assess the SOM within
soil samples. Samples were initially dried in an air forced oven for 72 hours at 70oC to
remove moisture. The samples were then ground using mortar and pestle to expose
material further, as the literature has highlighted that ignition of compacted soils is
unreliable if left in their natural state (Ravindranath & Ostwald, 2007). Due to the high
coal carbon content expected in the samples, these were placed at 300oC (below the
ignition temperature of coal) and 400oC, which is an accepted temperature for oxidation
of SOM / organic carbon (Jackson, 1985). Two temperatures were used due to the coal’s
potential to give false SOM weight loss readings (Salehi et al., 2011). Data collected
through calculations represented an indication of the SOM lost through the process of
WLOI.
2.7.4 Soil respiration assessment
The soils were assessed for respiration to investigate the level of biological activity
within the material. This can also give an indication of the SOM and its decomposition
(nutrient cycle).
Soil moisture within field samples was initially investigated. A 5g sample of each material
was weighed and placed within an air forced oven at 70oC overnight. The samples were
weighed again and the loss of weight was attributed to moisture content and evidence
suggested that the samples were distinctively different from one another (Weathered
52. 51
shale - 9.32%, Soil forming material - 12.37%, Overburden shale - 9.55%, Boulder clay -
15.4%).
After thoroughly mixing each raw core from their respective subplot, 10g of material (<
2mm) was placed within 50ml plastic centrifuge test tubes and sealed with parafilm.
(This sample represented the moisture conditions of the field). After 5 days of dark
storage with an average temperature of 21oC, a 5ml air sample was withdrawn from
each tube using a syringe. Using an “Environmental Gas Analyzer” (EGM-4, PP system)
to record the CO2 quantity within air samples via infrared measurement techniques, the
concentration of CO2 was recorded. This procedure was advised by Scullion (2015) and
partly used by Jenkinson & Powlson (1976).
A second set of samples were investgated using additional moisture (1ml of distilled
water) which was added to the samples with moisture content under 15%. This was to
aid microbial activity and create a closer unity of moisture across all samples. Rewetting
and creating a moisture content between 15-18% was advised by Scullion (2015) and
studies by Fierer et al., (2003) .
2.8 Statistical analyses
All data collected from this investigation has been statistically analysed using the “IBM
SPSS version 22 statistical Analyse package”. Whilst testing for homogeneity of variance
using the Levenes test, the data sets had generally a highly significant spread of variance,
which was also apparent when viewing the Standard Deviations for each set.
Transforming the data using LOG10 was unable to remedy the distribution of data, except
for Cut 3 and CO2 data sets. Therefore could not meet the equality of error variance,
which is an assumption needed to complete the Two Way ANOVA. However, whilst
53. 52
running the Two Way ANOVA it was clear where factors were having a significant effect
and this provided indications for the non-parametric tests to investigate further (Pallant,
2010).
Utilising the non-parametric Kruskal-Wallis analyses, which has stricter requirements to
meet significance, the data sets were able to be statistically analysed for significant
differences between factors. Subsequent investigations using Post Hoc Tukey HSD tests,
to identify where the differences were within these factors (Bonamente, 2013).
54. 53
3. RESULTS
Field data was collected onsite at the Miller Argent site at Merthyr Tydfil from November
2014 through to August 2015. Research focused on three main subjects: grass growth,
root development, and the soil/grass interaction. The overall aim of the experiment has
been to identify key traits of grasslands which could assist the reclamation of the coal
wasteland site and its potential after use value. These include the potential herbage,
SOM provided, root development, and respiration of the soils. The grass species
investigated included four parental grasses which acted as the control species within
this experiment. These consisted of two Fescue cultivars, Meadow Fescue (Festuca
pratensis cv. Bf1317) & Tall Fescue (Festuca arundinacea cv.Bn1482) and two HGC
Perennial Ryegrass cultivars, Aber Magic and Aber Dart. These four parental grasses
have been tested against four hybrid Festuloliums that have varying quantities of traits
from their parental grasses and moreover, a range of potential benefits for use on
materials and conditions that exist in coal reclamation sites. The Festuloliums
investigated included LpFg (Perennial Ryegrass x Mediterranean Fescue), LpFg2
(Perennial Ryegrass x Mediterranean Fescue –Partial hybrid), LpFm (Perennial Ryegrass
x Atlas Fescue), and finally Prior (Perennial Ryegrass x Meadow Fescue). Three replicates
of each species were randomly allocated a 1m x 1m sub plot making 24 subplots within
four separate soil materials. These plots represented materials available on site for a
potential grassland reclamation project. These included weathered shale, soil forming
material, overburden shale and boulder clay. The shales have been extracted from
depths, therefore have limited nutrients and unfavourable texture for vegetation
55. 54
growth. Whereas, both the boulder clay and soil forming materials represent material
that would be typical better suited as a replacement topsoil. All materials have been
stored for three years and exposed to weathering prior to the creation of the
experimental plots .This investigation has gathered data that represents the
experimental plots and cultivars in their third year after establishment in 2013.
Due to the nature of the field plot design, variance within grass species and the materials
in which they were sown has increased throughout the three years of the trial. The
statistical analyses of the data have been particularly challenging. Typically, to compare
the two independent factors against eight dependent factors, a Two Way ANOVA would
be utilised. Unfortunately, due to the considerable distribution range of the data
collected from the subplots, the variance was too dissimilar to meet the required
assumptions of a Two Way ANOVA. All data sets failed the homogeneity of variance,
Levenes test and even with transformation (log 10) the issue was not sufficiently
corrected across all data sets (Appendix 7.8). By ranking data and using a non-parametric
test (Kruskal-Wallis) plus a post hoc test, (tukey), significant differences were able to be
identified. Where both independent factors had a significant effect, the background
interference with each other was tackled by isolating each material plot and conducting
a One Way ANOVA with a Post Hoc, Tukey HSD test. The specific statistical analyses
procedure for each item investigated can be located in Table 1.
The Two Way ANOVA showed that there was no significant interaction found between
the set of two independent factors throughout the data collected, so this was not
57. 56
Table 1.Statistical analyses procedure for each individual investigation.
The results for the Levenes test of homogeneity are displayed to illustrate the variance issues even after transforming data. The Two Way ANOVA
indicated where the significance between groups could be found and the further statistical analyses section, shows the additional analyses where
necessary.
Investigated Result of Levene
test for
Homogeneity of
Variances
Result of Levene
test using
transformed data
(LOG10)
Two Way ANOVA
indicated effect
significance >0.05
Further Statistical Analyses
Grasses Soil
Cut 1 0.000 0.003 No No None
Cut 2 0.000 0.000 Yes No Kruskal-Wallis followed by a post hoc, Tukey.
Cut 3 0.015 0.251 Yes Yes Separated investigation into four separate soil plot and used a One Way
ANOVA ,followed by a post Hoc, Tukey
Cut 4 0.000 0.004 Yes Yes One Way ANOVA on each effect ,followed by a post hoc, Tukey
Cut 5 0.000 0.021 Yes Yes One Way ANOVA on each effect ,followed by a post hoc, Tukey
Total herbage 0.000 0.000 Yes Yes One Way ANOVA on each effect ,followed by a post hoc, Tukey
SOM at 300c 0.000 0.000 No Yes Kruskal-Wallis followed by a post hoc, Tukey.
SOM at 400c 0.000 0.000 No Yes Kruskal-Wallis followed by a post hoc, Tukey.
58. 57
Respiration (Co2) 0.000 0.001 No Yes Kruskal-Wallis followed by a post hoc, Tukey.
Respiration (Co2)
with additional
moisture
0.000 0.000 No Yes Kruskal-Wallis followed by a post hoc, Tukey.
Root mass 0.031 0.002 Yes Yes Separated investigation into four seperate soil plot and used a One Way
ANOVA ,followed by a post hoc, Tukey
Percentage
coverage
0.000 0.000 Yes No Kruskal-Wallis followed by a post hoc, Tukey.
59. 58
3.1 Herbage analyses
Grass samples from each plot were collected in five separate cuts from November 2014 to
August 2015. The duration of time between cuts was not standard, however, so between May
and August cuts were approximately every month. Throughout the histograms shown will
show result the calculated mean amount of herbage created by each cut.
This section will investigate individual cuts and the dry herbage collected from each group.
3.1.1 Cut One
Using a Two Way ANOVA, cut one was found to have no significant combined effects from
either the grasses and/or materials, relating to the total herbage. However, according to the
post hoc test, Prior and boulder clay produced the most herbage, and LpFm produced the
least. Soil forming material produced the least volume of yield. Due to no significant
differences at this stage, no further analyses were conducted.
3.1.2 Cut Two
Using a Kruskal-Wallis test, only the grass cultivars had a highly significant effect on the
herbage collected (X2 = 26.961, p = 0.000), refer to Table 2, for individual mean totals. The
following post hoc test, revealed that Bn1482 created significantly more than all of the other
species (P <0.05). All Festuloliums produced less than all parental species (see Figure 6). The
soil material did not have a significant effect on the herbage. However the post hoc test
indicated that the soil forming material did have a significantly great herbage than overburden
shale and boulder clay (P < 0.05).
60. 59
Figure 6. Total mean herbage (dry weight) collected from each group of grass cultivars from cut
two. All means and standard deviations (SD) have been calculated using the raw data (see
Appendix 7.2).
3.1.3 Cut Three
The Kruskal-Wallis test indicated that grass cultivars had a significant effect on the herbage
collected (X2 = 18.495, P = 0.010), refer to Table 2, for individual mean totals. An additional
post hoc test identified Bn1482 as producing the most overall herbage but only significantly
greater (p<0.05) than Aber Dart, Aber Magic, LpFg2 and highly significantly greater (p<0.001)
than LpFg and Bf1317.Two Festuloliums, Lpfm and Prior, produced the second and largest
amounts of herbage. Both cultivars were significantly greater (P<0.05) than the Fescue Bf1317
(See Figure 7).
61. 60
Figure 7. Total mean herbage (dry weight) collected from each group of grass cultivars from cut
three. All means and standard deviations (SD) have been calculated using the raw data (see
Appendix 7.2).
Materials also were having a highly significant effect on the herbage produced (X2 = 39.442, P
= 0.000), refer to Table 3, for means totals. According to the post hoc test, the weathered
62. 61
shale created the greatest herbage total yield and was significantly greater (P < 0.05) than soil
forming material and highly significantly (P <0.001) greater than the others (See Figure 8).
Figure 8. Total mean herbage (dry weight) collected from each group soil material from cut
three. All means and standard deviations (SD) have been calculated using the raw data (see
Appendix 7.2).
A One Way Anova and post hoc, tukey test were used to statistically analyse each data set
from each material to isolate difference and limit background variability originating from both
independent factors. On both soils forming material and boulder clay materials, Bn1482
produced the most herbage and consistently created significantly (P < 0.05) more herbage
63. 62
than Bf1317 and LpFg. Moreover, Bf1317 produced the least on all materials except soil
forming material.
On the weathered shale there were no significant differences in the herbage created (P> 0.05).
However, on overburden shale, Bn1482 again created the most herbage and was significantly
greater than LpFg and Bf1317 (P< 0.05).
3.1.4 Cut Four
The Kruskal-Wallis test indicated grass cultivars as having a highly significant effect on the
herbage collected (X2 =41.653, p = 0.000), refer to Table 2, for mean totals. An additional post
hoc test revealed that the Bn1482 produced a highly significant yield (P < 0.001), more yield
than all other species. The Fescue Bf1317 produced the least and was significantly lower (P <
0.05) than both Ryegrasses (Aber Dart & Aber Magic), refer to Figure 9.
The materials did not have an overall effect on the total herbage according to the Kruskal-
Wallis test.
64. 63
Figure 9.Total mean herbage (dry weight) collected from each group soil material from cut four.
All means and standard deviations (SD) have been calculated using the raw data (see Appendix
7.2).
3.1.5 Cut Five
The Kruskal-Wallis test indicated grass cultivars as having a highly significant effect on the
herbage collected (X2 = 37.353, P = 0.000), refer to Table 2, for individual mean totals. The
post hoc test identified Bn1481 as consistently creating the greatest amount of herbage
compared to all other species, at a highly significant (P < 0.001) difference. Festulolium
cultivars LpFm and LpFg produced the least herbage overall, with LpFm also producing
significantly (P < 0.05) less than Bf1317 (refer to Figure 10). It was worth noting that the LpFg
65. 64
had a P value = 0.053, compared to Bf1317, which indicated that the Festulolium was very
close to creating significantly less herbage.
Figure 10. Total mean herbage (dry weight) collected from each group over all four materials
during cut five. All means and standard deviations (SD) have been calculated using the raw data
(see Appendix 7.2).
Materials also were having a highly significant effect on the herbage produced (X2 = 16.599, P
= 0.001), refer to Table 3, for mean totals. The post hoc test identified the soil forming material
as giving the greatest herbage total yield and was significantly greater (P < 0.05) than both
weathered shale and overburden shale but not boulder clay.
66. 65
A One Way ANOVA and post hoc, tukey test were used to analyse each data set for each
material to isolate difference and limit background variability originating from both significant
independent factors. There was not a significant difference between the cultivars within the
weather shale and boulder clay materials. However, the cultivars within the soil forming
material expressed a highly significant difference (P< 0.001) and a significant difference (P<
0.05) was expressed between cultivars within the overburden shale. Bn1482 produced the
greatest yield overall in both materials. On the overburden shale, Aber Dart produced the
second greatest herbage volume and Bn1482 was significantly greater (P>0.05) than LpFg,
LpFm, Prior and the lowest producer, Bf1317. However, on the soil forming material Bn1482
was highly significantly greater (P<0.001) than LpFg and significantly greater (P<0.05) than
LpFm, moreover Bf1317 produced the second largest volume, and was significantly greater
(P<0.05) than LpFm.
3.1.6 Total Herbage
This section describes the analysis of the cumulative total herbage collected throughout all
cuts.
The Kruskal-Wallis test indicated grass cultivars as having a highly significant effect on the total
herbage collected (X2 = 29.586, P = 0.000), refer to Table 2, for individual mean totals. The
post hoc test, revealed that Bn1482 total herbage was highly significant (P <0.001) greater
than any other cultivar monitored over all materials, refer to Figure 11.
67. 66
Figure 11. Total mean herbage (dry weight) collected from each group of grass cultivars over all
four soil materials. All means and standard deviations (SD) have been calculated using the raw
data (see Appendix 7.2).
Materials also had a highly significant effect on the total herbage created (X2 = 16.407, P =
0.001), refer to Table 3, for means totals. An additional post hoc revealed that the soil forming
material created the greatest herbage total yield, but only significantly greater (P < 0.05) than
the worst material, overburden, which also produced significantly less herbage than
weathered shale, but not boulder clay.
A One Way Anova and post hoc, tukey test were used to analyse each data set on each
material to isolate difference and limit background variability originating from both
68. 67
significantly independent factors. There was no significant difference between cultivars on
weathered shale and boulder clay. However, there was a significant difference (P < 0.05) on
the soil forming material and overburden shale. Bn1482 created the greatest total herbage on
both materials and was consistently significantly (P >0.05) greater than Bf1317, LpFg and Lpfm.
It was also significantly greater than LpFg2 on soil forming material and Prior on the
overburden shale. Refer to Figure 12 & 13, for respective histograms illustrating these
differences.
Figure 12. Total mean herbage (dry weight) collected from each group of grass cultivars from
the soil forming material. All means and standard deviations (SD) have been calculated using
the raw data (see Appendix 7.2).
69. 68
Figure 13. Total mean herbage (dry weight) collected from each group of grass cultivars from
the overburden material. All means and standard deviations (SD) have been calculated using
the raw data (see Appendix 7.2).
70. 69
3.2 Percentage coverage
The Kruskal-Wallis test identified that there was a highly significant difference (P<0.001)
occurring between the grass cultivars (X2 = 40.805, p = 0.000) and a very high variability
accounted by the species groups (refer to Table 2, for individual mean totals). Bn1482 had the
greatest overall ground coverage and was highly significantly greater (P<0.001) than Bf1317
and significantly greater (P<0.05) than LpFg2. Festuloliums, LpFg and LpFm, created the second
and third greatest ground cover, respectively.
The Two Way ANOVA has indicated that there were no significant differences (P> 0.05)
between the percentage coverage, dependent on the materials. Even though the
homogeneity of variance failed, this result has meant that no further analyses were required.
However, the post hoc test revealed that soil forming material provided the greatest coverage
overall and overburden shale produced the least.
71. 70
Table 2. Cultivars mean totals from each investigation.
This data is the raw mean values which was collected from the field subplots and the laboratory experiments Although, this raw data was not
used for direct statistical analyse due to large variances, it does highlight the differences and similarities between sets of data.
Cultivars Mean Totals
Aber Dart Aber Magic Bn1482 Bf1317 LpFg LpFg2 LpFm Prior
Cut 1 (g) 92.84 94.32 92.69 80.07 76.36 96.29 76.22 97.78
Cut 2 (g) 96.41 93.01 171.41 88.00 55.89 75.22 73.51 74.22
Cut 3 (g) 132.64 124.92 195.30 76.05 106.83 128.82 146.41 146.24
Cut 4 (g) 133.14 130.37 199.31 80.51 104.41 96.16 112.37 110.43
Cut 5 (g) 43.62 37.98 83.85 48.97 24.62 41.38 24.34 34.36
Total (g) 498.66 480.60 742.56 373.60 368.11 437.86 432.85 463.02
Percentage cover (%) 76.00 73.17 89.17 64.33 83.42 66.83 82.17 77.25
SOM 300c (g) 3.06 3.28 3.13 3.65 3.21 2.97 6.92 2.93
SOM 400c (g) 7.71 8.10 8.60 8.03 8.39 8.20 7.62 7.97
Respiration-
Field moisture (ppm)
3574.58 4329.25 6509.42 4167.08 4177.75 4989.17 7427.25 3869.00
73. 72
Table 3.Material mean totals from each investigation.
This data is the raw mean values which was collected from the field subplots and the laboratory experiments. Although this raw data was not
used for direct statistical analyse due to large variances, it does highlight the differences and similarities between sets of data.
Soil Material Mean Totals
Weathered Shale Soil Forming Material Overburden Shale Boulder
Clay
Cut 1 (g) 90.96 69.18 91.35 101.79
Cut 2 (g) 88.96 120.85 74.27 79.77
Cut 3 (g) 192.29 151.69 79.24 105.38
Cut 4 (g) 112.77 143.63 111.46 115.49
Cut 5 (g) 35.14 55.89 28.21 50.31
Total (g) 520.13 541.24 384.52 452.74
Percentage cover (%) 77.50 80.00 72.00 76.67
SOM 300c (g) 2.74 3.06 5.70 3.08
SOM 400c (g) 8.41 5.57 12.64 5.70
75. 74
3.3 Soil Organic Matter (SOM)
The amount of SOM within the subplots was investigated with two different temperatures for
“Loss of Ignition –LOI”. This was due to the soil profile characteristics of the site which included
coal fragments, especially within overburden shale, as identified by the Cranfield reports
(Cranfield, 2015). This section will be divided by the temperature used, 300oC (coal doesn’t
burn) and 400oC (coal burns). The SOM was calculated as a percentage of the soil material
core obtained from each subplot and this was used for the statistical analyses to investigate
SOM differences between subplots and material plots.
3.3.1 Loss of Ignition at 300 oC analyses results
The Two Way ANOVA has indicated that there were no significant differences between the
grass cultivars. Even though the homogeneity of variance failed, this result has meant that no
further analyses were required. However, the post hoc test revealed that Prior provided the
least SOM overall and LpFm produced the most, but these were not significant differences.
The Kruskal-Wallis test identified that there was a significant difference in SOM between the
soil materials (X2 = 14.835, P = 0.002), refer to Table 2, for individual mean totals. The post hoc
test revealed that the overburden material produced the most SOM overall and was
significantly greater (P < 0.05) than weathered shale. Boulder clay produced the second largest
volume of SOM.
76. 75
3.3.2 Loss of Ignition at 400 oC analyses
The TWA analysis indicated that there were no significant differences between the grass
species. Even though the homogeneity of variance failed, this result has meant that no further
analyses were required. However, the post hoc test revealed that Bn1482 provided greatest
SOM overall and Aber Dart produced the least.
The Kruskal-Wallis test identified that there was a highly significant difference between the
amount of SOM created between the soil materials (X2 = 79.104, P = 0.000) with a high
variability accounted by the material group, (refer to Table 3, for individual mean totals).
Overburden produced highly significantly (P< 0.001) greater SOM than all other materials.
Weathered shale produced the second largest amount and this was highly significantly
different to the boulder clay and soil forming material, which produced the least.
3.4 Respiration
The following section has investigated respiration of the soil by measuring the CO2 ppm
released from 10g of soil. The experiments firstly analysed the samples in their field moisture
form and then another with additional moisture to optimise conditions for microbial activity.
3.4.1 Natural state sample CO2 analyses
The Two Way ANOVA indicated that there were no significant differences ( P> 0.05) between
the grass cultivars and the CO2 released. Even though the homogeneity of variance failed, this
result has meant that no further analyses were required. However, the post hoc test revealed
that Lpfm provided the greatest CO2 overall and Aber Magic produced the least.
The Kruskal-Wallis test identified that there was a highly significant difference between the
amount of CO2 created between the soil materials (X2 = 26.167, P = 0.000), refer to Table 3,
![1
DECLARATION
This work has not previously been accepted in substance for any degree and is not being
concurrently submitted in candidature for any degree.
Signed
...................................................................... (candidate)
Date ........................................................................
STATEMENT 1
This work is the result of my own investigations, except where otherwise stated.
Where *correction services have been used, the extent and nature of the correction is
clearly marked in a footnote(s).
Other sources are acknowledged (e.g. by footnotes giving explicit references).
A bibliography is appended.
Signed
..................................................................... (candidate)
Date ........................................................................
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