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ARTICLES >> Livestock Articles

Total Grazing Pressure

Posted by Bestprac on Aug 07 2013

by Liz Guerin

The contribution of non-domestic grazing pressure to pastoral areas of western NSW has been reported to increase grazing intensity by at least 50%. So, if you are a good manager and making stocking decisions to conserve feed, this can be a huge issue - both environmentally and financially.

Landholder Ashley McMurtrie, "Gilgunnia", Cobar, with NSW DPI Senior Research Scientist, Dr Cathy Waters and Technical Assistant, Robert Smith, examining results and water spreading and TGP fencing at "Gilgunnia"Total grazing pressure (TGP) is the combined grazing pressure of all herbivores (domestic, native and feral) on vegetation, soils and water. Managing TGP better, particularly in rangeland landscapes, can allow paddocks to be rested and ensure the sustainability of these areas but, importantly, maintain proper functioning of ecosystems and survival of native species.

Greg Brennan, Development Officer (Rangelands) with the Department of Agriculture and Food WA, said that management of grazing pressure is the 'be-all and end-all' of any grazing operation and producers have long known that it is in their economic best interests to protect and conserve groundcover. However, there are few incentives for pastoralists to control TGP. 

"Heavy grazing pressure in dry seasons has decimated perennial grass species in many shrubland environments," he said, "These species are preferentially grazed because they are often rich in the dietary energy needed to sustain growing lambs and lactating ewes. The palatable shrubs generally have higher levels of protein but are low in metabolisable energy. Research has shown that the continual grazing of these perennial grasses below 10cm is likely to cause their death in a following dry season.

Kangaroos need a diet of approximately 60% grass so they move about the landscape to satisfy this need, and like goats are unhindered by most boundary fences."

To add insult to injury, research shows that the perennial grasses are also responsible for holding water in the landscape and for regulating how water moves across the country. This explains how the decline of perennial grasses has helped effectively altered hydrological functioning, causing water to run out of the system.

Mr Brennan said that the pastoral industry in Western Australia recognises the challenge of slowing water movement down so it can soak in and gullies begin to heal. To do this, raindrop impact needs to be managed so that more often raindrops land on ground cover rather than splashing on bare soil.

"TGP control is being driven from two angles; an underpinning philosophy that without control of total grazing pressure we will get neither livestock productivity improvements nor improved natural resource outcomes," he said. "If pastoralists were able to economically control the grazing pressure of both kangaroos and goats, they would surely make more money from their domestic animals."

Recognising the environmental benefits of TGP control through increased groundcover, the Western Catchment Management Authority (CMA) have offered incentive funding for landholders to put up TGP fencing.

Senior Research Scientist (Pasture Systems) with NSW Department of Primary Industries, Dr Cathy Waters, said that they are not only looking at the use of TGP fencing and rotational grazing management and its influence on soil organic carbon, ground cover, diversity and landscape function. They are also looking at how economic it is to undertake management which results in more soil carbon being stored in the soil and better NRM outcomes.

"We want to understand the tradeoffs between beneficial NRM outcomes such as increased soil carbon, increased ground cover or biodiversity and the impact on grazing profitability or production," she said.

The impact of TGP fencing alone, and the impact of TGP fencing under different grazing regimes, (like set stocking versus rotational grazing) within that TGP fence, are currently being examined. Detailed studies are being undertaken at a number of core research sites and additional satellite sites are being used to up-scale the results. The results of these studies will have applicability not only regionally, but also across different enterprise types and management regimes. The major aim of this research is to understand what impact controlling grazing intensity has on soil organic carbon, ground cover and species diversity (and subsequently habitat and fauna diversity). To date preliminary results have shown almost twice the amount of bare ground in unmanaged areas with no TGP fencing, and less than half the number of perennial grasses when compared with areas managed with TGP fencing.

With some results of the project to be published later this year, Dr Waters said that one of the clearest differences to-date was found in the increases in ground cover. "What we have found is that some of the compositional differences are pretty varied depending on location but increased groundcover appears to be consistent across all sites studied to-date," she said.
One of the secondary benefits is the carbon sink potential – this project will also provide benchmark results on changes in carbon stock, under alternative management for western NSW.

In addition to this project, NSW DPI are also into the process of developing a restoration guide for the southern Australian rangelands, including different fencing designs and their costs. This manual is due to be completed mid 2014.

Both Mr Brennan and Dr Waters agree that the issue of managing TGP goes way beyond just having an exclusion fence.
"We have entered a new era of precision pastoralism, where managing your total grazing pressure is not just about managing kangaroos and goats (non-domestic grazers). Programs like Lifetime Ewe Management and CashCow show how fine tuning domestic numbers, to achieve target body condition scores, can improve the reproductive potential of their flocks and herds, without compromising the viability of perennial species, " Mr Brennan said.

Greg Brennan says that control of total grazing pressure can be both the biggest risk and the biggest opportunity currently in the Australian rangelands.

"The biggest risk is animal welfare and desertification, whilst the biggest opportunity is to quadruple the productive capacity of the Australian rangelands. The challenge is how we move forward with this. NRM organisations are showing the lead and facing up to this challenge."
 

Last changed: Aug 08 2013

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Comments

TGP By Paul Flipo on Aug 09 2013
It seems to me you have missed the point.
Building a roo proof fence around a 50,000 ac grazing property is very difficult and expensive,but not impossible.
What I need to know is how to get 20,000 or more roos out of the paddock....
Any suggestions?
Paul Flipo.

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