Bringing tropical
pastures south —
can it be done?
Summer fodder: Russell Ellis from NE
Victoria sowed this form of Warrego grass
(paspalidium distans) in 2009, and then
pasture cropped it with wheat in 2010.
He hopes to harvest seed from it during
April 2012.
The growing interest in practices such as pasture cropping and a desire to capitalise
on summer rainfall has increased interest in warm season pasture perennials
L
ivestock producers throughout
Australia are aware of the importance
of maintaining year-round ground
cover on their pasture paddocks.
But this can be challenging for
producers in southern Australia with
predominantly
improved
pastures
consisting of winter-active species.
Native,
summer-active
perennial
pasture species respond well to summer
rainfall and provide some grazing during
the warmer months, but feed quality can
be low for many of these species.
To bulk up summer feed quality, and
explore possibilities in pasture cropping,
producers in southern Australia have
begun trialling some of the more nutritious
C4 perennial pasture species to see which
can handle cold, wet winters and how to
best manage them for persistence.
Defining features
Perennial grasses can be classified as
either C3 or C4 plants, according to how
they capture carbon dioxide during
photosynthesis.
While all species have the more
primitive C3 pathway, which results in a
3-carbon molecule when carbon is fixed,
C4 plants produce a 4-carbon molecule
which enters the C3 cycle.
Although the two pathways are
associated, they have different growth
requirements.
C3 plants are adapted to cool season
establishment and growth in either wet
or dry environments, while C4 is are
more adapted to warm or hot (sub-tropical
and tropical) seasonal conditions under
moist or dry environments.
C3 grasses tolerate frost more than C4
species, and while they also generate less
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feed bulk, their feed quality is often
higher.
Table 1 shows the features of C3 and
C4 grasses.
Dual action
It is not uncommon to find both C3 and
C4 species in one paddock, especially if
there are different aspects and conditions
within the paddock to provide niches
each grass type can occupy.
On the South West Slopes of NSW it is
common to find C3 Weeping Grass
(Microlaena stipoides) and Wallaby Grass
(Austrodanthonia spp) and C4 Red Grass
(Bothriochloa macra) and
Kangaroo
Grass (Themeda australis) growing in the
same place.
But to provide greater groundcover and
feed across a range of conditions, the
more species of each type which can be
established in a paddock, the better.
Using management techniques such
as strategic grazing can stimulate many
C4 species in areas where they may have
once been common.
Others more exotic species can be
introduced by being sown or broadcasted
but may require careful management to
ensure successful establishment and
persistence.
Careful budgeting also needs to be
undertaken to look at the full cost of
sowing a tropical pasture and the amount
of time it takes to payback.
Southern experiences
Graeme Hand, chief executive of Stipa
Native Grasses Association, said he has
had few successes with C4 grasses in
southern Victoria except for kangaroo
grass and paspalum.
“The ideal conditions for establishment
of many C4 grasses appears to be a soil
surface temperature greater than 25C and
when soil moisture is around field
capacity,” he said.
“This does not occur frequently in
southern Victoria as many of the C4
Table 1 Features of C3 and C4 grasses
C3
C4
Initial molecule formed
during photosynthesis
3 carbon
4 carbon
Growth period
Cool season or yearlong
Warm season
Light requirements
Lower
Higher
Temperature requirements
Lower
Higher
Moisture requirements
Higher
Lower
Frost sensitivity
Lower
Higher
Feed quality
Higher
Lower
Production
Lower
Higher
Examples
Weeping grass and common
wheatgrass
Kangaroo grass, red grass and wire
grass
Source: NSW DPI
Farming Ahead April 2012 No. 243
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Photo: Russell Ellis
| Livestock Tropical pastures
Tropical pastures Livestock |
species do not go dormant in winter in
areas south of the Great Dividing Range.
They will be grazed out without long
recovery periods between grazing and
maybe just one grazing over winter.”
Nathan Ferguson, district agronomist
with NSW Department of Primary
Industries (Tumut, NSW), said during
January 2009 he sowed tropical grass
species in trials around Tumut and
Tumbarumba. After 18 months of weed
control leading into sowing, conditions
were ideal with a full soil-moisture profile
and 25mm rainfall just after sowing.
“Twelve species were sown in the trials,
and while some germinated, all failed to
persist through the winter,” he said.
“With interest in tropical grasses even
higher, I have sown five species this
summer (2011-12), based on those which
germinated in the previous trials, including
Buffel Grass, Premier Digit Grass,
Bambatsi Panic, Rhodes Grass and
Creeping Blue Grass.”
Nathan said time will tell how they
survive the winter and if they grow again
next summer.
Nigel Phillips, technical pastures
specialist with NSW Department of
Primary Industries (Wagga Wagga) said
while C4 grasses can at times be very
productive and of good feed value, reliably
predicting when feed will be available in
the summer dry environments of southern
Australia is difficult.
“The overwhelming majority pastures
with a C4 component are in the high
rainfall zones of the slopes and tablelands.
The few pastures that exist in the cropping
regions are usually remnant vegetation of
low productivity,” he said.
“To date most attempts at establishing
sub-tropical C4 pastures have been
unsuccessful.
“Where producers have existing C4
species they should be managed to preserve
or enhance the C4 component in
conjunction with other useful species. Acknowledgments ▶ Jacci Campbell
and Russell Ellis, Benalla, Victoria;
Nathan Ferguson, NSW DPI Tumut;
Graeme Hand, Branxholme, Victoria;
Nigel Phillips, NSW DPI Wagga Wagga;
Colin Seis, Gulgong NSW
Contact ▶ Russell Ellis
0427034629
Drought driving change
After enduring nearly 10 years of drought
and variable rainfall, the Ellis' were keen to
increase the proportion of perennial grasses
in their grazing system, to prevent paddocks
becoming too bare before the autumn break.
Russell Ellis and his family run an 1800-head,
self-replacing Merino flock, and a further
1550 Merino and crossbred ewes to support
their prime lamb enterprise.
They also have 40 Shorthorn-cross cows and
pasture crop between 100ha and 300ha each
year — more in drier years — to increase
winter feed.
The Ellis’ mainly crop with oats and some
wheat, keeping the grain for on-farm use.
“As part of our pasture-cropping program,
we wanted to include grass species in our
system that could make use of summer
rainfall," Russell said.
“Even though we traditionally have hot, dry
summers and cold, wet winters, summer
rainfall actually makes up about 40 per cent
of our annual rainfall on average,” he said.
“So in 2008 we started trialing a variety of
C4 perennial species, mainly as part of our
pasture cropping program.
Keeping cover
“One of our main aims in taking on this
method of farming is the enhance the soil
structure by maintaining ground cover - 100
per cent of ground cover 100 per cent of the
time," Russell said.
"This in turn will improve the water retention
of the soil, which is needed to cope with the
variable rainfall,” he said.
“By reducing the amount of bare ground, we
also hope to out-compete opportunistic weed
species and reduce the need to spray.
"This will increase the diversity and quantity
of soil microbes and maximise the diversity
of plant species, hopefully reducing the need
to continually sow new pastures.
“The C4 grasses we have sown are to be part
of a diverse range of grassland species in
each paddock, not a monoculture. However
we envisage not all the species will be
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natives, and some ‘traditional’ species will be
used as part of the diversity.
“If we can look after these grasslands using
tools such as intensive, rotational grazing,
we hope to remain viable in a market of
ever increasing costs over which we have
no control.”
Target species
The C4 species the Ellis’ have trialled over the
past four years include paspalidium distans
(sometimes referred to as a form of Warrego
grass), arm grass millet, cotton panic, red
grass, silky blue grass, Gatton panic, plantain,
chicory, curly windmill grass, windmill grass,
and early spring grass.
Russell said they have used a variety
of methods to sow the C4 species,
predominantly autumn sowing them at
various rates depending on the species, seed
availability and cost.
“Some of the native grasses have awns
on the seed which does not allow them to
be sown through conventional machinery,
so these are often broadcast and the area
pasture cropped with oats," he added.
Case study
Farm inform ation
Property owners
Russell, Helen,
Andrew and Ally Ellis
Location
Chesney Vale,
north-ea st Victoria
Property size
1000ha
Annual rainfall
550mm
Enterpris es
Wool, sheep meat, prime
lambs and cattle
“Those species which seed type allow have
been sown through the combine, mixed
with the fertiliser. The area is then pasture
cropped the following year.”
A cautious approach
According to Russell, the results of their C4
perennial species trials have been variable
but interesting.
In some crops he said the perennial plants
are seen the year of sowing, while in others
the C4 species have gradually germinated
over the following years.
“In the three areas we have trialled the
Warrego grass (paspalidium distans), it
appears to be performing particularly well,"
Russell said.
"Other grasses have established reasonably
well but do not seem to have the leaf matter
production of Warrego.
“Gatton panic sown in late spring 2011 also
established reasonably well, and the good
rain at the end of January and early March
2012 enhanced its growth.
"But it has not yet been grazed so we do not
know how it will perform or persist."
The Ellis’ admit their trials have not been
going for long enough to know how the C4
species persist in their climate.
Nor are there enough results to reliably
determine how the species will increase
in density, the level of grazing production
they will provide and if they will alter soil
structure or water retention.
“We realise the past two summers have
been unseasonably wet in this area and
have been ideal for establishing many of
these C4 species. But there have still been
challenges such as the dry spring of 2011 so
we will continue to trial all these species,”
Russell said.
“More seed will be sown and other areas
pasture cropped to enhance the natural
seeding and regeneration, to increase
plant density.
No. 243 April 2012 Farming Ahead
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