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Unit 1 - What's in it for me?
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Unit 3 - Can I trust the technology?
Unit 4 - Plant and animal performance
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Unit 6 - Do the $$$'s stack up?
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Site Assessment
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Solution 2: Volunteer pasture
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SOLUTION 2

Fence and volunteer pasture

 

2.4  Level of confidence in fence and volunteer pasture

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How reliable is the information?

With only limited economic analysis of this option, confidence in, and the reliability of the information would typically be low. However encouraging evidence about fence and volunteer pasture and its reduction or elimination of many of costs and risks associated with establishing pastures on saline land, mean this is not the case.

We can state reliably:

  • Except in the most extreme salinity situations, the overgrazing of plants of limited vigour is the major cause of bare ground on saline land.
     
  • While pasture establishment always carries a risk of failure, that risk is significantly magnified on saline sites.
     
  • Once fenced off from grazing, almost all but the most extremely salt scalded areas will revegetate. Areas that suffer severe periods of inundation generally remain bare; just about everything else will grow some kind of plant cover. In fact for the most highly saline and waterlogged areas, fencing off and removing all grazing is the recommended practice
     
  • The likelihood of ‘failure’ from fencing off and allowing volunteer pasture to establish is almost zero as long as there are desirable species adjacent to the area to act as a seed source.
     
  • The costs associated with fencing and volunteer pasture are always significantly lower than if a specific saltland pasture is sown.
     
  • Fencing and allowing a volunteer pasture to establish does not preclude a later decision to sow a pasture on the site.
     
  • In eastern states, sites fenced off from grazing will often be colonised by tall wheatgrass if that has been established on saltland nearby. Other species that can establish naturally in more severely affected areas in WA are samphire, small leaf bluebush and puccinellia.

There are other aspects of the fence and volunteer pasture strategy that reflect a relatively low level of confidence in our knowledge:

  • There has been no research to examine when volunteer pastures might be a better economic proposition than specifically established saltland pastures. However, as a general rule, the production advantage of sown saltland pastures over the ‘controls’ or volunteer pastures declines as sites become increasingly hostile due to salinity and waterlogging. This might indicate that the economics of volunteer pastures (compared to sown saltland pastures) rises with increasing salinity/waterlogging.
     
  • Actual levels of pasture production from these volunteer pastures have rarely been measured.
     
  • The composition of the volunteer pasture is hard to predict.
     
  • The rate of establishment of the volunteer pastures has not been determined, nor has there been any study into the sorts of management that could increase this natural accretion of productivity. However, we do know how dramatic the long term impact can be.
     
  • There has been no research into how grazing or other management practices might encourage either more desirable saltland species into the volunteer pastures or for it to happen more quickly.
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Farmer experiences

There are few published examples of farmer experiences with fencing and volunteer pastures, a reflection of the lack of promotion of such a strategy by research and extension agencies who were the likely collectors and publishers of such anecdotes. Likewise, there has been little commercial interest in saltland solutions that require no seed, chemical or other inputs.

However, in the SGSL initiative some coincidental insights into the fence and volunteer pasture option emerged. It is reflected in the fencing of smaller areas and controlling grazing management. The desire of farmers to adopt pasture improvement options has been a reflection of farmers having large areas of unproductive land that has limited grazing potential.

The NSW Network Committee commissioned an economic evaluation of saltland management (see Section 2.3 How do the $$s stack up?). While the economic focus was on the returns from establishing saltland pastures, other insights also emerged from the study. The report states:

Farm B landholder considers significant environmental benefit (without loss of productivity) can be gained at low cost by simply changing grazing management on saline areas that occupy less than 5% of his 814 ha property.

Some saline sites on Farm B have not been sown to saltland pasture. The landholder has managed these sites using a planned grazing process consistent with holistic management principles. Stock are grazed a minimum of 6 days to a maximum of 10 days per year. Grass species are allowed to colonise bare areas during the periods free of stock. Results from this grazing management approach show, in paddocks previously with significant areas of scalding, bare ground has been revegetated and species diversity has improved to a level equal to elsewhere on the property. In particular, these areas now contain more species of native perennial grasses than are present on other areas of the farm
.

Another similar insight emerged from one of the SGSL grower network sites in Western Australia. For more information, see “Productivity potential of salty country”. Most of the discussion in the case study is about a trial to improve saltland pasture, but in the ‘word from the gate’ section at the back, Dr Ed Barrett-Lennard made the following observations:

Sometimes the big message that we get from a research site is not about the success of what we tried, but about what nature did. The story from the SGSL work at the Carter’s farm appears to be one of those instances.

SGSL had two trial sites at the Carters’ near Wubin in WA (285 mm rainfall) – one site associated with the Producer Network and another site associated with the WA2 research project. At each location, nature had a pretty important message to tell us about small leaf bluebush (Maireana brevifolia). Bluebush is a valuable salt tolerant plant that grows and spreads naturally. Quite thick stands of bluebush grow in the road reserves near both of the SGSL sites on the Carter’s farm. With the control of grazing on these sites, seed from the road reserves invaded the SGSL sites to provide a very useful productivity bonus.

For many years we have talked about the ’low cost’ method of establishing saltland pastures – put up a fence and allow natural regeneration to occur. In Western Australia, bluebush is the most important species using this approach. It looks as if the two SGSL sites at the Carter’s farm are well on their way to being revegetated using this simple and effective technique
.

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What are the main risks and challenges?

In almost all the other Saltland Solutions, a major risk is associated with the fact that saline sites are hostile environments for most plants, and especially for establishing seedlings. This makes the risk of pasture establishment failure significantly higher than on non-saline land.

With the Fence and volunteer pasture Saltland Solution, there is little risk of establishment failure. Fencing off a saline site from grazing will result in vegetation establishing there, which in most cases will be able to be grazed for at least part of the year. The only major exception to this is where the naturally establishing plant is samphire: these species can have ash concentrations in the leaves up to 40% and we would recommend that these plants not be grazed. To some degree, the susceptibility of saltland to major colonisation by samphire can be predicted. The seeds are generally carried in moving water – risk of inundation is therefore a driver – and samphires also have relatively specific requirements for subsoil salinity and depth to watertable as outlined in Saltland Solution 1 – Fence and exclude from grazing.

While there is some risk associated with the fact that the volunteer pasture that establishes will likely be less productive and/or less nutritious, and/or less profitable than if a saltland pasture was established, this risk is partly offset by the fact that the establishment cost is minimised.

There is also some risk that the volunteer pasture will include significant weeds such as spiny rush. If this is the case, and weed control is needed, then the cost of the option will be increased.

In addition, the decision not to establish a sown saltland pasture can be reversed – the site has already been fenced, allowing sowing a purpose designed saltland pasture at any time. The plant species that naturally colonise the area can be of great value as indicator species. A period of natural revegetation can give important clues to the best kinds of pasture species to sow in future.

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Prospects

Current research

There is no current research into the fence and volunteer pasture option, and it is a Saltland Solution that has been overlooked in almost all projects since saltland pasture research began in the 1950s.

Despite this, the re-examination of the SGSL research projects has shown how profitable and risk free the option can be.

We would recommend that all future research avoid the problems encountered by SGSL, where fence and volunteer pasture, rather than the original site condition became the control. This resulted in the economics of sown saltland pasture being underestimated because it measured only the additional gain above fence and volunteer pasture, rather than the total gain above the original site production. A good starting point for all future saltland pasture research would be to quantify the potential gains from fence and volunteer pasture at a site, as well as the potential, additional gain from a sown saltland pasture. This is especially the case in the eastern States where fence and volunteer pasture seems to offer better prospects than it does in WA, and often better prospects than sown saltland pastures.

Future prospects

Given that farmers are often strongly motivated by non-economic drivers when revegetating saline land, a Saltland Solution that maximises the area brought under good management and improved visual amenity per dollar spent would seem to be a winner.

Though largely ignored by researchers and commercial interests in the past, the simplicity, economic attractiveness and low risk associated with this option would suggest that it should be considered.

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