The need to adapt forage species to a changing climate in pasture based agriculture.
BR Cullen1, RP Rawnsley2, RJ Eckard1, MJ Bell1, K Christie2
1
Melbourne School of Land and Environment, University of Melbourne, Victoria.
2
Tasmanian Institute of Agriculture, University of Tasmanis, Burnie, Tasmania.
Introduction
Adopting plant species with deeper roots, higher heat tolerance and/or greater summer activity are
commonly suggested as adaptations for warmer and possibly drier future climates expected in southern
Australia. In temperate regions of south eastern Australia this may include, for example, replacing
perennial ryegrass with deeper rooted species such as tall fescue and phalaris, or incorporating more
heat tolerant C4 species such as kikuyu into the forage system. These species are all currently used in
livestock production systems in southern Australia and have been selected by producers to fit the
climatic niche of the farm and the characteristics required in the production system. An important
question is: how will the production characteristics of these perennial grass species change in future
warmer and drier climates?
Across southern Australia there is a range of pasture species sown related to annual rainfall and growing
season length, together with characteristics required by the livestock production system. In the high
rainfall regions (>750 mm annual rainfall) perennial ryegrass is the dominant species. It is favoured in
these regions due to its high productivity and nutritive value, ease of grazing management, good
responses to N fertilizer and rapid establishment. It is however susceptible to heat stress and fails to
persist at the lower end of this rainfall zone, two of the key aspects of the climate that are likely to be
challenged in future. Tall fescue is a deeper rooted species than perennial ryegrass, capable of higher
levels of production in the warmer months of the year. Phalaris is a perennial grass typically sown in the
550-750 mm rainfall zone, where perennial ryegrass fails to persist. By comparison, it is deeper rooted
and moderately more heat tolerant than perennial ryegrass; it also has a greater level of summer
dormancy making it more persistent in this rainfall zone. While C4 grasses are not commonly used in SE
Australia, there has been recent interest in using kikuyu because of its heat tolerance and deep rooted
growth habit together with its summer activity potentially providing feed when C3 pastures are of below
optimum feed quality and/or failing to grow. C4 species however are inherently lower in forage quality
than C3 species thus resulting in lower animal production per unit of intake and potentially more enteric
methane production per unit intake. When evaluating forage options differences in quality must be
taken into account.
This brief review indicates that there is a diversity of use of perennial grass options in SE Australia
according to the existing climate. Grazing systems have been established on these plants because they
are well adapted to the environment. The need to adapt the forage base in response to a changing
1
climate will occur when an alternative option provides an improvement over the existing pasture
system. This may be assessed on a number of different levels:
 Annual ME production (taking into account DM and metabolisable energy content)
 Seasonal production (taking into account DM and metabolisable energy content)
 Persistence (related to length of dry periods).
 Year to year variability in production
In this paper the options for adapting to climate change by using deeper rooted and heat tolerance traits
are assessed by modeling the annual and seasonal production of a range of perennial grasses under
historical and possible future climate scenarios at a range of sites in southern Australia. Different levels
of climate change are imposed, representing the range of probable changes out to 2070, using the
‘resistance surfaces’ approach developed by Cullen et al. (2012).
Methods
Sites and pasture types simulated
A description of the sites is provided in Table 1. The sites spanned a range of climatic zones from cool
temperate at Elliott in north-west Tasmania to subtropical at Mutdapilly in south-east Queensland. At
each site three or four pasture types were simulated based on different perennial grasses. The species
modeled at each site represented species currently used in each region and species that may also be
suitable in warmer and drier climate scenario. The pasture types simulated at each site are defined in
Table 2.
The perennial grass species simulated were perennial ryegrass, tall fescue, phalaris, native C3, native C4,
kikuyu and Rhodes grass. The key differences between the perennial grass species simulated can be
summarized in terms of root distribution, shoot:root partitioning of carbon assimilates, photosynthesis
response functions, high and low temperature tolerances and tissue flux response functions (Table 3).
In terms of adaptation to future warmer and drier future climates, key differences between the species
were in root characteristics and responses to high temperatures (Table 3). To compare the rooting
characteristics of three different perennial grasses as examples, the maximum rooting depth for
perennial ryegrass was 40cm, phalaris was 160cm and kikuyu was 200 cm. For the deeper rooted
species a higher proportion of photosynthate was allocated to the roots, ie. 20% for perennial ryegrass
versus 30% for phalaris and kikuyu (Table 3).
There are also differences between the species in their response to maximum temperatures (ie. heat
stress). For perennial ryegrass, heat stress begins to limit plant photosynthesis when the maximum
temperature reaches 28°C and stops photosynthesis when it reaches 35°C (Table 3). Recovery from heat
stress requires a T-sum of 50 which equates to 10 days of mean daily temperature of 20°C to fully
recover. The onset of heat stress for phalaris occurs at a higher temperature (30°C), but time to recover
is longer (T-sum= 200, equating to 40 days of mean daily temperature of 20°C to fully recover). This
2
longer recovery time reflects the summer dormancy of phalaris. By contrast, heat stress does not affect
kikuyu until temperatures are higher and it recovers quickly, but its growth is limited by minimum daily
temperatures less than 8°C.
A mean annual metabolisable energy (ME) content for each of the pasture types was specified. This
value was used across sites and seasons, and in the future climate scenarios. The values used were:
perennial ryegrass 11.0 MJ ME/kg DM, tall fescue 10.5, phalaris 10.5, phalaris/nativeC4 9.5, native C3/C4
9.5, kikuyu 9.0, and Rhodes grass 9.0.
The simulations were carried out using DairyMod (version 4.8.6) with non-limiting soil nutrients. The
simulated pasture management was a monthly cut trial where pastures were cut to a residual mass of
1.4 t DM/ha on the last day of each month.
Climate scenarios
The baseline period was at each site was from 1/1/1971 to 31/12/2010, a forty year period centred on
1990. Future climate scenarios were generated by scaling the baseline climate using combinations of 0,
1, 2, 3, 4°C warming (380, 435, 535, 640 and 750 ppm CO2 respectively) and +10, 0, -10, -20, and -30%
rainfall (ie. the resistance surfaces approach of Cullen et al (2012)). For each site the number of hot and
cold days and nights (using the definitions of CSIRO and BoM 2007) under the five temperature regimes
are shown in Table 4.
Data analysis
Annual and seasonal pasture production was expressed as GJ ME/ha based on the simulated pasture
harvest in each month and the pasture ME content (described above) for each climate scenario. The
inter-annual variability of pasture production was presented as the coefficient of variation (CV %).
The mean number of days per year and wet (soil water content > field capacity) and dry (soil water
content < 0.5 readily available water (RAW), where RAW is the mid-point between field capacity and
wilting point) was also calculated for each pasture type and climate scenario. The soil water content
calculations were made to 40cm soil depth for all pasture types. Mean annual runoff and drainage was
also calculated.
No statistical analysis of the climate scenarios was carried out because of inter-correlations in the way
the scenarios were created.
Results
Mutdapilly
Of the irrigated C3 pasture species, perennial ryegrass had higher ME production than tall fescue and
phalaris but all these species were predicted to decline in production with moderate levels (+1-2°C) of
warming (Fig 1). The irrigated C3 pastures provide greater ME production than Rhodes grass in winter,
3
even with warming (Fig 1). The rain-fed Rhodes grass is tolerant of warming, but its production is very
sensitive to changes in rainfall with declining production simulated in the lower rainfall scenarios.
At this site, the modelling suggests that a 30% decline in rainfall will lead to approximately a 50% decline
in runoff (Fig 2).
In the historical climate at Mutdapilly there are few wet days and many dry days (Fig 2). The
proportional changes in these numbers in the future climate scenarios are not large.
Moree
The pasture types at Moree that incorporate a C4 species (either C4 native or Rhodes grass) are more
productive under current climate than the phalaris only pasture, and also are more tolerant of warmer
temperatures (Fig 3). The phalaris pasture also has higher inter-annual variability (measured as CV%).
The one advantage of the phalaris only pasture is that it is more productive than native C3/C4 and
Rhodes grass in winter, but less in other seasons (Fig 3).
There was little effect of pasture type or warmer climate scenarios on runoff, but runoff declined in the
lower rainfall scenarios (Fig 4). At this site there were few wet days and many dry days in current and
future climates (Fig 4), and the proportional changes in wet/dry days in the future scenarios were not
large.
Albany
In the historical climate scenario there was little difference in annual ME production from perennial
ryegrass, phalaris and kikuyu, but perennial ryegrass and phalaris both declined with warming while
productivity of kikuyu pasture increased (Fig 5). Kikuyu and Perennial Rye were more sensitive to rainfall
decline than Phalaris, while phalaris was more resilient to warming than perennial ryegrass (Fig 5).
Kikuyu was more productive than the C3 species in spring and summer and this difference increased with
warmer scenarios, but the difference was not as large with -30% rainfall (Fig 5). Warming increased
winter production in all species, but +3-4°C is required before winter production of kikuyu can match
that of the C3 species (Fig 5).
In terms of water balance, warming alone at the Albany site was simulated to reduce drainage, by about
60 mm/year with +4°C, and this was exacerbated by lower rainfall (Fig 6). The warmer and drier future
climate scenarios increased the number of dry days and reduced the number of wet days (Fig 6).
Wagga Wagga
Pasture types that incorporated the C4 native grass at Wagga Wagga had annual ME production in both
current and future climates (Fig 7). The phalaris/native C4 pasture type also had a relatively even
distribution of production throughout the year. Phalaris was more productive than perennial ryegrass
(Fig 7), and the high and increasing number of dry days will likely further challenge perennial ryegrass
persistence in this environment (Fig 8).
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The simulations showed that drainage will be reduced to near zero with a 30% reduction in rainfall
under perennial ryegrass and a 10% rainfall reduction under phalaris only and phalaris/native C4 pasture
types (Fig 8).
Dookie
In the historical climate phalaris is more productive than perennial ryegrass and kikuyu at Dookie (Fig 9).
In the future climate scenarios phalaris production is predicted to decline with +3-4°C warming while
kikuyu will increase a little under the same scenarios. With large rainfall declines (-30%) phalaris is more
productive that kikuyu.
Phalaris was more productive than kikuyu in all climate scenarios in winter, and in spring until >+2°C
warming occurs (Fig 8). Kikuyu was simulated to be more productive in summer under all climate
scenarios, even though its production declined with warming.
Runoff was not affected by pasture type or warming, but declined with reduced rainfall (Fig 10).
Drainage was highest under perennial ryegrass followed by phalaris and kikuyu (Fig 10), and was
reduced by warming and lower rainfall. Overall an increasing number of dry days under warmer and
lower rainfall scenarios (Fig 10), is likely to reduce persistence of perennial ryegrass.
Hamilton
In the historical climate tall fescue was a little more productive than phalaris, followed by perennial
ryegrass (Fig 11). Kikuyu was less productive than the other species in current climate. Kikuyu may
become more productive than the other species with >+2°C warming provided there is little decrease in
rainfall.
Kikuyu has potential to complement production of the temperate species by providing more production
in summer (Fig 11), particularly as temperate species decline in warmer climates. However kikuyu
production in winter was less than the temperate species under all climate scenarios.
The increasing number of dry days in the warmer and drier future scenarios (Fig 12) may limit
persistence of perennial ryegrass. Runoff was not affected by pasture type or warming, but declined
with reduced rainfall (Fig 12).
Terang
In the historical climate the rank order of annual ME production was tall fescue > perennial ryegrass =
kikuyu > phalaris (Fig 13). Of the temperate species, production of tall fescue and phalaris declined with
increasing temperatures while perennial ryegrass increases with 1-2°C warming then declines with
further warming (Fig 13). Phalaris production was more resilient to lower rainfall compared to other
species (Fig 13). Kikuyu will be only be more productive than temperate species with >1°C warming
provided that rainfall does not decline by more than 10% (Fig 13).
5
Kikuyu does have potential to complement production of the temperate species by providing more ME
in summer (Fig 13), particularly as temperate species production declines in warmer climates. However
kikuyu production in winter was less than the temperate species under all climate scenarios.
The increasing number of dry days with warming and reduced rainfall (Fig 14) may limit persistence of
perennial ryegrass. Runoff was not affected by pasture type or warming, but declined with reduced
rainfall (Fig 14).
Ellinbank
In the historical climate scenario, perennial ryegrass, tall fescue and kikuyu produced similar amounts of
ME while phalaris was lower (Fig 15). Production of the temperate species was predicted to decline
with warming while kikuyu was predicted to increase. However, temperate species will remain more
productive than kikuyu in winter.
Annual drainage was simulated to be lower with the deeper rooted species, and drainage declined with
warming and lower rainfall scenarios (Fig 16). An increasing number of dry days was predicted in the
warmer and drier climate scenarios, although the total numbers of dry days per year was less than at
the Terang and Hamilton sites. The simulated reduced number of wet days may reduce winter pasture
damage.
Elliott
In the historical climate, tall fescue and phalaris produced more ME than perennial ryegrass, while
kikuyu had lower productivity than the temperate species (Fig 17). All temperate species were
predicted to increase production with warming. Kikuyu would not become more productive than
temperate species until there was 4°C warming. The benefits of kikuyu providing higher summer
production were not as large as at other sites, owing to higher levels of temperate species production at
this site.
The modeled trend was towards reduced number of wet days (which may lessen winter pasture
damage) and more dry days in the future climate scenarios (Fig 18).
Discussion
Future warmer and drier climate scenarios will alter the balance between the productivity and
persistence of perennial grasses to support livestock production systems. The impact of climate
scenarios will affect regions differently. Those regions that are currently hot and dry (eg. Moree and
Wagga Wagga) will remain so, but existing pasture types at this location based on a mix of C3 and C4
species appears to be quite resilient to the changes in climate.
In other regions, hotter and drier conditions are likely to challenge the productivity and persistence of
current pasture species, particularly where the current species are near the edge of their adaptive
range. A good example of this is perennial ryegrass based pastures at Hamilton and Terang in southwest Victoria. While perennial ryegrass is well adapted to cope with increasing temperature alone, tall
6
fescue (a deeper rooted option) offers some growth advantages particularly in summer. Phalaris (a
summer dormant option) appears more resilient to rainfall declines and offers higher levels of
persistence under hotter (Table 3) and drier (Figs 12 and 14) conditions. In these environments, C4
grasses will be well suited if the climate becomes warmer but only if there is not a substantial decline in
rainfall. The low winter production of C4 species at the sites in southern Victoria, even in warmer
scenarios, will continue to be a limitation to the use of this species.
In a cool temperate site such as Elliott, perennial ryegrass production will increase in warmer and drier
scenarios and its benefits in ease of management are likely to see it continue to be widely used.
However as the climate becomes warmer and drier, deeper rooted options such as tall fescue and
phalaris may be integrated into the systems particularly as they provide higher levels of production over
summer.
Overall, increasing numbers of hot and dry days will challenge persistence shallow rooted perennial
grasses such as ryegrass. This will tend to favour the summer dormant species such as phalaris,
however the tradeoff between the ease of management of ryegrass with the persistence benefits of
phalaris is likely to be amplified in many regions of southern Australia.
There appears some evidence to support the notion that C4 grasses like kikuyu could be integrated into a
component of the farm under warmer climates because it offers a complementary growth pattern to
the temperate species. However it is not expected to be more productive than temperate species
without the combination of substantial warming and limited rainfall decline. Kikuyu is very reliant on
summer rainfall to grow, so its production is highly susceptible to rainfall decline. In addition low winter
production will limit its adoption as feed grown through this period is valued a lot higher by farmers
The results of this analysis have highlighted that changes in the relative performance of pasture species
is expected in future climates based on their heat tolerance and rooting depth. It has also raised further
questions and issues that need to be addressed as we attempt to design forage systems adapted to
warmer and drier climates. For example:



The tradeoff between production and persistence will change and be amplified across southern
Australia. This will influence farmers’ choice of species.
The role of summer active temperate species (eg lucerne) requires further consideration. The
analysis presented here suggests that there is a niche here, to complement species with winter
dominant growth patterns. We are already seeing farmers switching to more lucerne (on
suitable soils), this and other summer-active options require further work.
Can intensive pasture production systems based on mixed C3/C4 species in southern Australia be
developed? Their complementary growth patterns suggest that this would be desirable. Such
systems do exist for example in mixed ryegrass/kikuyu swards in coastal NSW, except there they
winter irrigate the ryegrass while we may need summer irrigation to keep the kikuyu alive.
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Table 1. The location soil types, annual rainfall (mm, 1971-2010) and climate zone of the sites simulated.
Soil typeA
Annual rainfall
Climate type
Red mesotrophic
1245
Cool temperate
haplic ferrosol
Ellinbank
-38.25, 145.93
Red mesotrophic
1033
Temperate
haplic ferrosol
Terang
-38.25, 142.85
Brown chromosol
771
Temperate
Hamilton
-37.83, 142.06
Brown chromosol
680
Temperate
Dookie
-36.37, 145.70
Vertic calic red
568
Warm temperate
chromosol
Albany
-34.90, 117.80
Petroferric brown
755
Temperate
sodosol
Wagga Wagga
-35.10, 147.30
Red chromosol/
539
Warm temperate
leptic tenosol
Moree
Clay loam
587
Subhumid
Mutdapilly
-27.63, 152.71
Black vertosol
836
Subtropical
A
in all cases soil depth was specified to 2 m to allow maximum rooting depth for kikuyu.
Site
Elliott
Lat./Long.
-41.08, 145.77
Table 2. The pasture types simulated at each site.
Site
Elliott
Ellinbank
Terang
Hamilton
Dookie
Albany
Wagga Wagga
Moree
Mutdapilly
Perennial ryegrass,
white clover
Perennial ryegrass,
white clover
Perennial ryegrass,
white clover
Perennial ryegrass,
subterranean
clover
Perennial ryegrass,
subterranean
clover
Perennial ryegrass,
subterranean
clover
Native C4, phalaris,
sub, annual rye
Native C3/C4
Irrigated perennial
rye
Pasture types simulated
Tall fescue, white
Phalaris, white
clover
clover
Tall fescue, white
Phalaris, white
clover
clover
Tall fescue, white
Phalaris, white
clover
clover
Tall fescue, sub
Phalaris,
clover
subterranean
clover
Phalaris,
Kikuyu,
subterranean
subterranean
clover
clover
Phalaris,
Kikuyu,
subterranean
subterranean
clover
clover
Phalaris, sub,
Perennial ryegrass,
annual rye
sub, annual rye
Phalaris, sub
Rhodes grass, sub
Irrigated tall fescue
Irrigated phalaris
Kikuyu, white
clover
Kikuyu, white
clover
Kikuyu, white
clover
Kikuyu,
subterranean
clover
-
-
-
Rhodes grass
8
Table 3. Key biophysical parameters for the perennial grass species simulated in DairyMod.
Parameter
Leaf appearance interval at
20°C (days)
Leaves per tiller
Partitioning of new growth to
leaf + sheath
N content optimum,
maximum (%)
Min T photosynthesis (°C)
Opt T photosynthesis (°C)
Cold stress: on-set (°C)
Cold stress: full (°C)
Cold stress: recovery (T-sum)
Heat stress: on-set (°C)
Heat stress: full (°C)
Heat stress: recovery (T-sum)
Leaf flux – temp: min, opt (°C)
Leaf flux scalar at GLF
water=0, GLF water=1
Maximum root depth (cm)
Depth for 50% root
distribution
Root partitioning with no
water or nutrient stress (%
new growth)
Perennial
ryegrass
10
Tall
fescue
10
Phalaris
Kikuyu
10
Native
C3
20
Native
C4
20
Rhodes
grass
10
10
3
70
3
70
4
60
6
60
4
50
4.5
50
6
60
4.0, 5.0
3.5, 4.0
4.0, 4.5
3.0, 4.0
2.0, 2.5
2.0, 2.5
3.0, 4.0
3.5
20
28
35
50
3.0, 20.0
2.0
20
30
35
200
0.0, 20.0
2.0, 0.5
8.0
32.0
8
1
10
34
39
10
5.0,
20.0
2.0, 0.5
3.0
20.0
0.0,
20.0
2.0, 0.5
10.0
35.0
10
5
400
0.0, 20.0
2.0, 0.5
2.0
20
28
35
50
3.0,
20.0
2.0, 0.5
2.0, 0.5
12.0
35.0
7
3
50
5.0,
20.0
2.0, 0.5
40
15
120
50
150
30
200
50
60
20
100
25
200
40
20
23
30
30
20
20
30
9
Table 4. Mean number of hot days (maximum temperature>35°C), hot nights (minimum temperature
>20°C), cold days (minimum temperature <15°C) and cold nights (minimum temperature <5°C) per
annum at each of the site with 0, 1, 2, 3 and 4°C warming.
0
1
Hot days
Hot nights
Cold days
Cold nights
11
42
0
31
18
64
0
21
Hot days
Hot nights
Cold days
Cold nights
31
46
12
60
45
65
6
46
Hot days
Hot nights
Cold days
Cold nights
4
0
32
14
5
1
15
6
Hot days
Hot nights
Cold days
Cold nights
21
16
69
89
27
24
51
69
Hot days
Hot nights
Cold days
Cold nights
8
5
106
114
13
8
86
89
Hot days
Hot nights
Cold days
Cold nights
7
1
132
99
9
2
103
69
Hot days
Hot nights
Cold days
Cold nights
6
1
115
54
7
2
79
31
Hot days
Hot nights
Cold days
Cold nights
4
1
115
58
6
1
87
37
Hot days
Hot nights
Cold days
Cold nights
0
0
182
99
0
0
152
69
Warming scenario (°C)
2
Mutdapilly
28
88
0
14
Moree
62
84
3
34
Albany
7
5
6
2
Wagga Wagga
36
35
34
51
Dookie
18
13
65
66
Hamilton
13
3
69
46
Terang
9
4
46
17
Ellinbank
9
3
58
22
Elliott
0
0
118
42
3
4
43
112
0
8
64
138
0
5
81
104
1
23
101
124
0
14
9
12
2
0
12
24
0
0
45
47
19
35
57
60
11
22
25
19
44
46
33
27
26
31
16
6
39
28
21
9
19
15
12
7
21
8
15
11
7
3
11
7
33
12
16
13
15
5
0
1
82
22
0
4
46
10
10
(a)
(b)
Figure 1. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for irrigated perennial ryegrass, tall fescue and phalaris,
and rain-fed rhodes grass pastures at Mutdapilly under the temperature (°C) and rainfall (%)
change scenarios.
11
(a)
(b)
Figure 2. Mean annual runoff (mm) (a) and wet and dry days (b) for rain-fed rhodes grass pasture
at Mutdapilly under the temperature (°C) and rainfall (%) change scenarios.
12
(a)
(b)
Figure 3. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and (b) seasonal production (GJ ME/ha) for phalaris, native C3 C4 and rhodes grass pastures at
Moree under the temperature (°C) and rainfall (%) change scenarios.
13
(a)
(b)
Figure 4. Mean annual runoff (mm) (a) and wet and dry days (b) for phalaris, native C3 C4 and
rhodes grass pastures at Moree under the temperature (°C) and rainfall (%) change scenarios.
14
(a)
(b)
Figure 5. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, phalaris and kikuyu pastures at
Albany under the temperature (°C) and rainfall (%) change scenarios.
15
(a)
(b)
Figure 6. Mean annual drainage (mm) (a) and wet and dry days (b) for perennial ryegrass,
phalaris and kikuyu pastures at Albany under the temperature (°C) and rainfall (%) change
scenarios.
16
(a)
(b)
Figure 7. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, phalaris and C4 native, phalaris
pastures at Wagga Wagga under the temperature (°C) and rainfall (%) change scenarios.
17
(a)
(b)
Figure 8. Mean annual drainage (mm) (a) and wet and dry days (b) for perennial ryegrass,
phalaris and C4 native, phalaris pastures at Wagga Wagga under the temperature (°C) and
rainfall (%) change scenarios.
18
(a)
(b)
Figure 9. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, phalaris and kikuyu pastures at
Dookie under the temperature (°C) and rainfall (%) change scenarios.
19
(a)
(b)
(c)
Figure 10. Mean annual runoff (mm) (a), drainage (mm) (b) and wet and dry days (c) for
perennial ryegrass, phalaris and kikuyu pastures at Dookie under the temperature (°C) and
rainfall (%) change scenarios.
20
(a)
(b)
Figure 11. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, tall fescue, phalaris and kikuyu
pastures at Hamilton under the temperature (°C) and rainfall (%) change scenarios.
21
(a)
(b)
(c)
Figure 12. Mean annual runoff (mm) (a), drainage (mm) (b) and wet and dry days (c) for
perennial ryegrass, tall fescue, phalaris and kikuyu pastures at Hamilton under the temperature
(°C) and rainfall (%) change scenarios.
22
(a)
(b)
Figure 13. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, tall fescue, phalaris and kikuyu
pastures at Terang under the temperature (°C) and rainfall (%) change scenarios.
23
(a)
(b)
(c)
Figure 14. Mean annual runoff (mm) (a), drainage (mm) (b) and wet and dry days (c) for
perennial ryegrass, tall fescue, phalaris and kikuyu pastures at Terang under the temperature (°C)
and rainfall (%) change scenarios.
24
(a)
(b)
Figure 15. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, tall fescue, phalaris and kikuyu
pastures at Ellinbank (red ferrosol) under the temperature (°C) and rainfall (%) change scenarios.
25
(a)
(b)
Figure 16. Mean annual drainage (mm) (a) and wet and dry days (b) for perennial ryegrass, tall
fescue, phalaris and kikuyu pastures at Ellinbank (red ferrosol) under the temperature (°C) and
rainfall (%) change scenarios.
26
(a)
(b)
Figure 17. Mean (a) annual pasture production (GJ ME/ha) and coefficient of variation (CV %)
and seasonal (b) production (GJ ME/ha) for perennial ryegrass, tall fescue, phalaris and kikuyu
pastures at Elliott (red ferrosol) under the temperature (°C) and rainfall (%) change scenarios.
27
(a)
(b)
Figure 18. Mean annual drainage (mm) (a) and wet and dry days (b) for perennial ryegrass, tall
fescue, phalaris and kikuyu pastures at Elliott (red ferrosol) under the temperature (°C) and
rainfall (%) change scenarios.
28