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Site Assessment
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SOLUTION 5

Tall wheatgrass

 

5.4  Level of confidence in tall wheatgrass

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NOTE - the Future Farm Industries CRC's own weed risk assessment has determined that Tall Wheat Grass poses a 'very high' environmental weed risk in Victoria and is therefore now not recommending its use in this state.

How reliable is the information?

There is considerable research and farmer experience with tall wheatgrass over many years providing a high level of confidence in it as an option for saltland.
The relevant agencies in four states have produced basic information sheets that cover well-tested establishment and management techniques for tall wheatgrass. 

NSW Agnote on tall wheatgrass

WA Farmnote - Tall wheat grass and balansa clover

VIC AGNote 1287 Management of Tall Wheat Grass

Tassie Technote Salt Tolerant Pastures

We can state reliably:

  • Tall wheatgrass performs well on soils affected by low salinity (ECe 2-4 dS/m) and moderate salinity (ECe 4-8 dS/m) in southern Victoria, the ranges of Victoria and NSW, the upper south-east of SA and the south coast of WA;
     
  • Tall wheatgrass is damaged by salinity/waterlogging interactions. It is therefore not suited to soils affected by high levels of waterlogging.
     
  • While tall wheatgrass has been widely used and studied in southern states, it has recently been shown to be productive and persistent further north with encouraging results during long-term drought conditions.
     
  • The strengths (persistence, water use, out-of-season feed) and weaknesses (cost, animal nutrition limitations and profitability) of tall wheatgrass either as a single species or in a species mix are reasonably well tested and understood.
     
  • Dundas, a variety that was released commercially in 2000, is the preferred option for both livestock production and for reducing weed risk. It has similar salinity and waterlogging tolerance to the old variety Tyrell.
     
  • Tall wheatgrass is generally regarded as a pasture for higher rainfall zones, up to as much as 800mm, but is drought tolerant and will withstand levels of annual rainfall as low as 425mm.
     
  • The ready adaptability of tall wheatgrass to a range of Australian conditions has inevitably meant that it can pose a weed problem if not well managed. This is well demonstrated by infestation of roadsides in the upper south-east of SA. 
     
  • Accordingly,  the Future Farm Industries CRC's own weed risk assessment has determined that Tall Wheat Grass poses a 'very high' environmental weed risk in Victoria and is therefore now not recommending its use in this state. For South Australia, New South Wales and Western Australia the weed risk assessment outcome was a "high" weed risk. 
     
  • Establishment techniques for tall wheatgrass have been well developed and tested and each state has its own fact sheets.

There are other aspects to the use of tall wheatgrass that are not so clear:

  • There are few records of actual animal performance when grazing tall wheatgrass pastures.
     
  • There is potential for fodder conservation (hay and silage) from tall wheatgrass with flow-on management benefits for the grass as it matures rapidly. For more information, see the Manilla Film Clip. However there is little information available on the nutritional and economic value of this fodder.
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Farmer experiences  

“I accept that I can no longer crop much of the valley flats, but I will not accept that I can no longer graze them.” Tim Heffernan, Wickepin, WA, first saw tall wheatgrass in 1984 when visiting a farm in South Australia. “The farmer showed me his salt problem, but all I could see was a paddock covered in waist high green feed in the middle of summer!”

Since then, Tim has gradually transformed 150ha of marginal valley flats into forage areas for around $140 per hectare. 


These comments, in a 1996 DAFWA Farmnote probably reflected the views of many farmers at the time looking for opportunities to deal with increasing amounts of saltland. However, the same Farmnote also referred to preliminary work by WA researchers, where Merino wethers grazing tall wheatgrass showed little improvement in liveweight or wool production compared to those grazing unimproved saltland pastures.

Since then extensive trials, along with farmers’ experiences, have demonstrated the importance of good management to get the full potential benefit from tall wheatgrass. Dairy farmer Ken Shone, Beeac, Victoria, (annual average rainfall 550mm) is a strong advocate, but emphasises that management makes all the difference between good and poor outcomes:

“We first tried tall wheatgrass in the late 1970s in plots sown by the Department of Agriculture. It spread and did quite well, so we decided to sow it across the paddock in 1985, mainly to tackle salinity.

“The first paddock was sown with just tall wheatgrass. I would have to admit it wasn't well managed. It grew wild and rank and the cows didn't like it. But it was better than bare ground and sea barleygrass.

”In later sowings we set out to boost the protein levels with clover. The paddocks were sown with tall wheatgrass, tall fescue, balansa clover, strawberry clover and Persian clover, using direct drilling, combined with DAP fertiliser applied at 60 kilograms per hectare.

“What we found was that unless we kept the tall wheatgrass down, the clovers couldn't compete. When we did manage the grasses we produced a better grazing mixture and could start to think about hay and silage.”

The analysis of silage, hay and green pasture samples taken from tall wheatgrass based pastures on Ken's and another property in the area has continued each year since 1994-95 and the results have consistently demonstrated that high quality feed can be produced with careful management. Averaged over 5 years, tall wheatgrass paddocks in October showed 67% digestibility, 9.4 MJ/kg DM and 14.1% crude protein.

Energy and crude protein levels in tall wheatgrass begin to decline as it enters the reproductive stage, so Ken keeps the tall wheatgrass grazed hard so that it remains green and leafy and doesn't develop the tussocky growth it is known for.

“We cut it for silage towards the end of September or early October. In the paddocks not cut for silage we use a mower or mulcher where necessary to handle any rank growth. You have to cut it just above the crown and keep it above the clover. It's not top silage, but it's better than barleygrass and for what we've got, it's an excellent product.”


Sheep grazier Michael Blake, Hamilton, Victoria (690mm annual average rainfall) sowed 30ha of salt affected land to Dundas at 7kg/ha through an air seeder along with balansa and strawberry clover in 2000, a further 30ha in 2001 and another 30ha in 2003. 

After a poor establishment (due to technical sowing problems) the tall wheatgrass was allowed to set seed and then crash grazed during the first summer season. The pasture stand then improved significantly and has supported a stocking rate of 23DSE/ha during the 8 drier months of the year for the past 3 years (up from 2.5DSE/ha prior to pasture establishment).

The pastures are managed using a 2 paddock grazing rotation for a fixed interval of 6 weeks per paddock. Whilst this isn’t recognised as optimal management as it doesn’t allow for seasonal changes in pasture growth, it works sufficiently well to maintain pasture quality.

“In an early trial along a recharge area that flows into the Fern Hill Creek, we fenced and tried Tyrell tall wheatgrass. It did alright but became pretty tussocky over time based on management practices recommended in the early 1980s.

“Our plan is to use winter active lucerne on the higher ground to improve the pasture utilisation of the water available. The whole process incorporates a rotational system of grazing to maintain a balanced level of nutrition for our superfine/fine wool Merino sheep enterprise.

“It’s really all about growing wool at a minimum of 2.5mm a week, every week for eight months to supply to specific Italian markets with a minimum of 40 newtons per kilotex.

“The tall wheatgrass and lucerne combination will contribute to our pasture availability throughout the year to satisfy this requirement.

“There is a disadvantage though, with increasing production on the saltland we’ve gone from 2.5DSE to 26DSE and it has been hard to keep up with our pasture improvement program on non-saline land. We are now improving a saline area with an area not affected by salt to keep the pasture improvement program in balance.

“I believe our saltland can be the best land on the farm and now we have a pasture species that uses the water. It gives us good green feed early in the season to wean our lambs onto and it gives us green feed well through summer and autumn.”


In the Upper South East of SA an SGSL producer group investigated the sensitivity of tall wheatgrass productivity to variables such as soil salinity, sodicity, nutrients, and waterlogging on 8 properties. One of the graziers, Charlie Bruce, concedes that he had always been sceptical of the value of applying fertiliser to saltland. However, the grazing trials demonstrated the potential productivity gains if both nitrogen and phosphorus levels are adequate.

“In this region, it is difficult to carry enough stock during winter because the flats get so wet and boggy, but by the end of spring tall wheatgrass can have bolted and be so rank that nothing will eat it. Managing this so that a potential resource is not wasted was something we were keen to investigate.

“The other issue is that most of us are uncertain about the worth of adding fertiliser to what might be low value saltland pasture – what should you add, at what rate, and what are the benefits?

“So, we wanted to see if we could use fertiliser and grazing management to make better use of these tall wheatgrass and puccinellia pastures.

“We all knew that there would be differences in soil properties from paddock to paddock and from property to property, but we were surprised to find just how strongly these seemed to influence pasture production and fertiliser response. Annual pasture cuts ranged from 3 to 12 tonnes per hectare, apparently mainly reflecting the different soil depths and levels of salinity.

“It is one thing to grow a pasture, but will it grow an animal? The feed tests showed little difference between the fertiliser treatments, but did show that by November the quality of the feed had deteriorated significantly.”  

Farmers in northern NSW have also had good success using tall wheatgrass. For more information, see Banoon NSW SGSL site and Bannockburn NSW SGSL site.

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The main risks and challenges

Establishment. Many of the difficulties in establishing tall wheatgrass are those associated with most pastures on saline sites. Because saline sites are often waterlogged for significant periods, there can often be only a small window of opportunity to control weeds and sow the pasture following the opening rains of the season. In higher rainfall areas spring sowing is often preferred, but the risk here is that surface soil salinity levels can rapidly escalate if the season ends abruptly.

Tall wheatgrass is often sown with other pasture species which can require a compromise in sowing methods, particularly with puccinellia which has a very fine seed which should not be buried with harrows.

The relatively slow establishment of tall wheatgrass often requires that it be allowed to set seed in the first year to thicken up. This implies a further year’s wait for the pasture to come into anything like full production. On soils of low salinity balansa clover can out-compete tall wheatgrass and should be sown in the second year.

Agronomic/grazing management. Management of the mature pasture is very important. Good management can mean the difference between a productive sward and paddock that is almost impossible to drive across, is almost completely unpalatable, has low nutrient status, provides no space for complementary species, and acts as a source of potential weed seed. The specific grazing management required to keep tall wheatgrass productive and palatable make it a poor companion species when used in shotgun mixtures.

Weediness. The ready adaptability of tall wheatgrass to a range of Australian conditions has inevitably meant that it can pose a weed problem if not well managed – as demonstrated by infestation of roadsides in the upper south-east of SA. Tall wheatgrass is not a strong competitor as a seedling, so is unlikely to invade non-saline areas where there is established vegetation. However, it should not be planted near native vegetation or saline watercourses, and should not be included in seeding mixtures if the site is not to be grazed regularly. Managing the pasture to prevent seed set beyond the year of establishment should be the aim, as not only does this minimise the risk of spread, it also prolongs the productive vegetative phase of the pasture. Accordingly, the CRC's own weed risk assessment has determined that the species poses a "very high" environmental weed risk in Victoria and is therefore not recommended for use in this state.

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Prospects

Current research

Tall wheatgrass and puccinellia have long been the mainstay grasses for revegetating saline discharge areas, particularly in the eastern states and South Australia. Dense saltbush plantings and saltbush with under-storey have been the preferred in the generally lower rainfall salinity sites in WA.

The long term focus on tall wheatgrass as a mainstay of saltland pastures means that there is a considerable bank of research information underpinning the recommendations about its use and management.

However, work by the CRC Salinity has brought a focus to other grasses, some of which exhibit significantly higher salt-tolerance than tall wheatgrass.

The Salinity CRC screened a range of legumes for salinity and waterlogging tolerance and the evaluation of grass species is a continuation of that work. Grasses are generally more salt-tolerant than legumes, so the salinity levels used to challenge the grasses were twice as high as that used for the legumes.

Seed and vegetative material were collected from salt-tolerant native grasses over the 2005/06 summer, and this material is being evaluating by researchers from the Future Farm Industries CRC.

So far the researchers have evaluated the salt tolerance levels of around 40 species of introduced and native grass species, along with nutritive values and tissue ion measurements.

The trial has already found a native grass, Sporobolus mitchellii (rat’s-tail couch), with similar tolerance to high salinity as puccinellia. A range of other grasses has been found which, while not as tolerant as puccinellia, are more tolerant of salinity than tall wheatgrass.

While overall productivity in some of these species may be lower than that of tall wheatgrass or puccinellia, the aim in this research is to identify species that combine good productivity with high salt-tolerance. Researchers are now evaluating several of these species in field experiments in South Australia and Western Australia respectively.

The challenge for on-going research is to identify species that combine high production potential with high salt-tolerance.

Future Prospects

There are currently no major research projects focussing on tall wheatgrass pastures. However this option has previously received significant research attention with little to indicate that major breakthroughs are still to be made.

The lack of current research is not a negative reflection on the future prospects for tall wheatgrass based pastures in Australia. It is more a reflection of the fact that salinity research has declined in all southern states in recent years as risk estimates have been lowered, and salinity expansion has slowed following the recent run of dry years.

The overall prospect for tall wheatgrass as one of the primary/mainstay species in saltland pastures is assured. Tall wheatgrass-based pastures will continue to be the grass species of choice in south-west Victoria and tall wheatgrass will contribute in other regions of relatively high rainfall and moderate salinity.

The development of a wider range of salt-tolerant legumes would greatly expand the opportunities for tall wheatgrass.

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