There are many environmental problems with
introduced grasses in northern Australia; altered fire regimes
which in turn damage our native vegetation is just one of them.
However, improved pastures are an important part of cattle
production for many markets. Agricultural consultant Trevor
Howard looks at some strategies the grazing industry and
government are implementing to help contain exotics while reaping
the benefits.
Exotics versus natives
| Beef standards tighten | Codes of practices | Weeds or
Pastures | Accreditation framework
|
A past issue of Savanna Links highlighted the problems
associated with introduced pasture grasses in northern Australia.
1,2 The author, David Bowman, portrayed the introduction
of gamba grass Andropogon gayanus as an evolutionary experiment
that pits northern Australian savanna ecosystems against an
extremely fire-tolerant African grass.
There is no doubt that gamba grass is a major fire problem in
unmanaged situations as it contributes to fuel loads far in excess
of native grasses and cures much later in the dry season. There is
now ample evidence of native vegetation being severely degraded by
fires fuelled by gamba grass to warrant serious concern.
The problem is not confined to gamba grass. Para grass
Brachiaria mutica also alters fire regimes on Northern
Territory floodplains and wetter areas, and buffel grass Cenchrus
ciliaris has similar effects in more arid areas. Elsewhere in the
wet tropics of northern Australia guinea grass Panicum maximum is a
species which has deleterious impacts on fire regimes and native
vegetation. 3,4 Even Tully Brachiaria humidicola, a
successful and popular grass for pasture and hay that grows in a
low dense sward, burns with considerable intensity when cured. The
gamba grass issue is part of a much bigger debate about the
introduction of exotic grasses for cattle production.
While native pastures will remain the dominant component of the
north’s grazing systems, there are limits in using native
pastures for beef production across the high-rainfall monsoonal
areas of northern Australia. Despite moderate growth during the
annual wet season perennial grasses become dormant during the dry
season and annuals die after setting seed.
While native grasses may be well adapted to the seasonal cycle,
the growth of cattle in these conditions follows a saw-tooth
pattern with weight gains punctuated by periods of weight loss.
Animals may require several seasons to achieve market weight but
the resulting carcase may not be suitable for quality beef or high
returns. To some extent, improved pastures are also limited by
these cycles, but on the whole they tend to be more productive,
resulting in a more consistent growth path for cattle, a younger
turn-off and a higher quality carcase.
The advantages of improved pastures are being keenly felt now
that beef markets are becoming more competitive and animal
specifications are tightening. Under the domestic Meat Standards
Australia tenderness guarantee scheme the growth path of cattle is
an important factor in the acceptance process which excludes older
animals raised on an erratic plane of nutrition. For live export
cattle, age and weight requirements are specified and premium
prices are paid for young animals suitable for optimum performance
in the Asian feedlot industry.
In this context, improved perennial pastures have advantages as
they offer higher energy, digestibility and protein levels as well
as a capacity to carry more stock during the growing season and
beyond. Many, such as gamba grass, use moisture efficiently and
remain palatable and productive for longer into the dry season than
their native counterparts. An important attribute of some of these
grasses is their resilience under grazing pressure and their
contribution to erosion control. Improved pastures are now an
important part of cattle production for many markets. Where
improved pastures are sown, sound management practices to prevent
off-site environmental and fire control problems are essential.
With quality assurance schemes such as Cattlecare now integral
to many production and marketing pathways it is only a matter of
time until whole property management becomes a focal point for some
markets.
Industry is certainly recognizing and responding positively to
the signs. Ongoing concerns about the potential weediness of the
valuable forage legume Leucaena leucocephala have prompted
commercial growers in Queensland to develop an industry Code of
Practice 5 The Code of Practice provides management
guidelines for producers who wish to plant leaucaena or reduce the
likelihood of problems with existing plantings.
Gamba grass offers similar opportunities for a Code of Practice.
There is no doubt that gamba grass can be managed in a pastoral
situation, although it is no longer recommended by government in
the Northern Territory 6 . At a recent gamba grass
control workshop in the Northern Territory, Jeff Little, manager of
Opium Creek Station, pointed out that although it is twice as
difficult as other improved pastures to manage, it can be done
successfully.
While many people argue for the declaration of gamba grass as a
noxious weed, followed by a big-stick approach from government,
this will not remove the issues, infestations or plantings. Perhaps
in areas such as the rural residential hinterland of Darwin the use
of legislation could have some merit. But any blanket declaration
would be unrealistic given the cost of enforcement and the fact
that large-scale plantings are still used on many pastoral
properties.
Ongoing debates about whether gamba grass is a weed or a pasture
are meaningless and unproductive. Gamba grass can be both,
depending on the context in which it occurs and the perspective of
the individual. We now know that gamba grass can be effectively
controlled with glyphosate 7 and that seed viability
declines to a minimum over 12 months so that control efforts can be
very rewarding. 8 What is needed is a process that
engages everyone including pastoralists and conservationists, which
promotes best practice in animal production enterprises as well as
control programs, and which communicates the success stories from
both pastoral and conservation perspectives.
Considerable progress has already been made in this regard. Some
recent workshops in both the Northern Territory and Queensland have
attracted participants from all sides of the fence and have
exchanged information of value to all. In November, 2000, a
workshop near Darwin was attended by nearly 100 people from
conservation and land management agencies, the pastoral industry,
landcare groups, fire authorities, horticulturists, small rural
block owners and traditional owners. Effective control techniques
were demonstrated and the results of successful control programs
were presented.
Land managers are very interested in understanding how to manage
and control these new grasses. Learning to live with existing
introduced grasses appears to be the most realistic option.
The ISO 14000 accreditation framework, which is concerned with
the local and regional environmental impacts of production systems
and the policies and practices of an organisation, may well be the
yardstick by which future producer performance is measured in
discriminating markets.
The use of pasture species that improve animal production but
contribute to the degradation of natural resources may limit
domestic processing options or may jeopardise Australia’s
position in overseas markets unless sound management practices are
demonstrated. Meat and Livestock Australia is about to fund a pilot
study to explore the potential for developing an Environmental
Management System for the beef industry based on ISO 14000
standards. 9 Another proposal is being developed to
establish environmental codes of practice for the northern beef
industry. 10 Obviously this will not happen overnight to
resolve current problems and issues, but if current trends continue
there will be a major shift in beef production and marketing over
the next few years.
Trevor Howard is the Coordinator of the Vernon Region
Fire and Weed Project, funded by the Natural Heritage Trust.
Contact details below.
References
1. Bowman, D. (1999), 'Introduced grasses:
triumph or Trojan horse?' Savanna Links , Issue 10
July-August, pp. 6-7.
2. Quirk, M. (1999), 'Cut and dried: the issue is how to manage
disturbance', Savanna Links , Issue 10 July-August, p.
7.
3. Grice, A. & Slatter, S. (Eds), (1996), Fire in the
Management of Northern Australian Pastoral Lands , Tropical
Grassland Society, Occasional Publication No. 8.
4. Wallmer, M., (1994), 'Grass fuel build up over time on
tropical hillslopes', Proceedings of the Fire Ecology
Workshop , S. van-Cuyenberg (Ed) Darwin NT August 1994, Parks
and Wildlife Commission NT, pp. 30-33.
5. Leaucaena Growers' Association, (2000), 'Gospel according to
St. Leuc,' TGS news & views , Vol. 16, No. 3 August, pp.
5-6.
6. Northern Territory Government, (2000), Gamba Grass
Information Sheet, NTDPIF, (see link below).
7. Northern Territory Government, (2000), Tips for control of
mission and gamba grass in the Top End , NTDPIF Tech Note.
8. Flores, T., (1999), Factors affecting the recruitment of
Andropogon Gayanus Kunth , Honours Thesis, Northern Territory
University.
9. Anon, Summer (2000), 'Study on Environmental Certification',
NAP News , Issue 16, Meat and Livestock Australia, pp. 11
.
10. Anon, Summer (2000), 'Environmental codes of practice
proposal in new CRC phase', NAP News , Issue 16, Meat and
Livestock Australia, pp. 8-9.
