Saltbush as forage

24.05.17

Saltbush is the general name of a plant family (Chenopodiaceae) that is found all over the world, in desert, seashore, saline and damp environments. There are many types of saltbush native to Australia, ranging from small succulent-like groundcovers to tall woody shrubs.

Overview

Saltbushes are a dominant and important component of natural ecosystems in low rainfall and arid regions of Australia. They are an ideal and frequently chosen species for lowering watertables and reclaiming saline land. Some species of saltbush are recognised as valuable forage for livestock.

The largest of the Australian saltbushes is old man saltbush, Atriplex nummularia (Lindl.). It is a very hardy, perennial shrub adapted to a wide range of environments. It can grow to three metres high and 2–4 metres wide, has thick leaves that are silver-grey in colour, and its woody stems are generally brittle. Old man saltbush is extremely long-lived and records indicate that some plants are over 100 years old.

The value of old man saltbush as a forage plant for sheep and cattle was recognised by graziers in the mid-1800s. However, overgrazing of natural stands, extended drought through the 1940s and the added grazing pressure of rabbits saw widespread depletion of saltbush in rangeland ecosystems.

Remnant stands and new on-farm plantings have maintained the reputation of the species as a valuable supplementary forage, especially in late summer and autumn when annual and perennial pastures may be depleted. While saltbush is a valuable forage source, it should account for no more than 30–40% of the diet at any time because of its high salt and sulphur levels.

There is increasing interest in developing perennial-based grazing systems for low rainfall areas and for a changing climate when rainfall may be less predictable and dry periods extended. Old man saltbush is likely to be a key species in these systems. Old man saltbush is also a key species for salt-affected land where waterlogging is not a problem.

Many farmers claim that meat of stock grazed on saltbush has the marketable benefits of leaner, richer, moister and better tasting meat, compared with the meat of stock that haven’t grazed saltbush. There is scientific evidence of lambs grazing saltbush prior to processing having leaner carcasses with higher meat yields and higher vitamin E levels. Vitamin E is associated with maintaining meat redness and extending shelf-life.

Facts and figures

  • Members of the saltbush family of plants, Chenopodiaceae or chenopods, grow naturally all over the world
  • Old man saltbush is one of 250 species world-wide belonging to the Atriplex genus of the saltbush family, and one of 61 species in Australia
  • Bluebush, a species common through the arid areas of Australia, also belongs to the family Chenopodiaceae
  • The hardiness and adaptability of old man saltbush in arid environments has led to its exportation to many arid and semi-arid parts of the world
  • It is important that old man saltbush is used as supplementary feed and it should account for no more than 30–40% of the diet at any time because of its high salt and sulphur levels
  • Saltbush provides a good  source of protein and minerals at a time of year when pasture and crop stubbles are often depleted and of low quality
  • The life of a well-managed saltbush plantation could be productive for over 70 years and poorly managed stands may only last 10–12 years

Production status

Saltbush is grown extensively in saline systems in the cropping zone of Western Australia. Increasingly, it is being planted on soils that are marginal for cropping in the low to medium rainfall zones of all the southern states and southern Queensland.

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Map of current and potential growing regions

Uses

The hardiness, tolerance of salt and deep root system of old man saltbush has seen it planted extensively in its natural habitat and beyond its natural distribution, to lower watertables and revegetate salinised land. Because it is a perennial plant, it reduces erosion by slowing wind and water movement throughout the year, preventing surface erosion.

The dense foliage provides a good windbreak and shelter for stock. In agricultural landscapes largely cleared of natural vegetation, saltbush provides habitat for invertebrates and small birds. It recovers well after intense defoliation.

In addition to environmental benefits, old man saltbush provides a range of financial benefits when incorporated into agricultural systems. It is regarded as a key species for perennial-based grazing systems in low rainfall areas and an important part of grazing systems in the future farming climates. It is a key species for low to medium rainfall areas where the soil is impacted by dryland salinity.

Old man saltbush is a valuable source of supplementary forage for livestock. Being a summer-active plant, it makes good growth during the warmer seasons and provides fresh feed in late summer and autumn when grass-based pastures are often depleted. It also offers an alternative grazing option to allow grass and legume pastures to be spelled at critical times such as flowering and seed-set.

Saltbush provides a palatable source of crude protein, sulphur, minerals and antioxidants. These nutrients are particularly important because annual pastures have little or none through summer. The sulphur and crude protein is very useful in wool production systems. Saltbush also contains vitamin E, important for preventing muscle wasting over summer, and it may also improve the colour and shelf life of the meat.

An alternative source of food, particularly high in energy and low in salt, must be on offer when stock are grazing saltbush as it is a moderate energy, high salt food source. It is best considered as a supplement rather than an entire diet. The ideal complementary fodder is pasture established as an understorey between the rows of the saltbush, crop stubbles, hay, otherwise grain or pellets can be fed to livestock. If the supplement has low energy, reproducing and growing animals benefit from grain and/or pellets.

Production Requirements

Growing regions

Old man saltbush is endemic to the western plains of Queensland and New South Wales, northern Victoria, the central and northern regions of South Australia, the southern third of the Northern Territory, and the eastern goldfields region of Western Australia.

As an agricultural plant, saltbush has been established well beyond its natural zone into the cooler and wetter regions of New South Wales (the southern tablelands), north east Victoria, and southern South Australia.

Soil type

Old man saltbush grows naturally on a range of soil types but is found primarily on heavier clay and clay loam soils but it does persist on sandy soils. It is generally well adapted to soils of low fertility and tolerates low phosphorus levels. It prefers soil pH(Ca) in the range of 4.0–8.5.

It has moderate to high tolerance of saline soil conditions and saline groundwater. Good growth can occur at soil salinity levels (ECe) of 12–20 deci Siemens per meter (dS/m).

Old man saltbush can develop roots to four metres deep in the soil. However, with roots at this depth, saltbush is sensitive to waterlogging, particularly at high temperatures. If periodic waterlogging is likely, river saltbush (Atriplex amnicola) is a better choice.

Climate

Old man saltbush occurs naturally in regions of 150–600mm annual rainfall. While saltbush can survive very dry conditions, establishment of stands without watering is unlikely in regions with less than 300mm annual rainfall – unless there is periodic summer rainfall during the establishment year.

Saltbush withstands a large variation of temperature in its natural environment. It is a summer-active plant and optimum growth occurs between 30–35°C. Growth is slowed at temperatures below 10–13°C reflecting its dormancy between late May and late August. It is also very frost tolerant.

Saltbush is unaffected by the high daytime temperatures of arid environments and it is known for its drought tolerance. The shrub has many physiological adaptations to cope with drought, including a deep tap root system and the ability to shed leaves in dry periods. Leaf shedding during hot dry spells in Autumn has led to the development of the ‘use it or lose it’ message for producers.

Varieties

Most old man saltbush seed and seedlings come from provenance stock, ensuring its adaptability and performance in a given region. Two lines of old man saltbush are available as commercial varieties.

The variety de Koch was selected from lines of saltbush in South Africa but the parent material of these lines was originally native to Australia, possibly southern Queensland.

Another variety is Eyres Green, which is produced from plants cloned from an original plant on the Eyre Peninsula of South Australia, selected for its low growth habit and palatability.

Through the Old man saltbush improvement program, the Future Farm Industries CRC used a combination of sheep preference and traditional agronomic and laboratory measurements to help select the most palatable and digestible lines of old man saltbush. From an original collection of 60,000 seedlings and a series of selection processes and field trials, lines to be commercialised have been identified.

As well as improving energy content of the feed, the new saltbush plants will produce up to eight times more biomass and be about 20% more digestible than the average of the ‘wild’ population from which they originated.

Planting and crop management

Old man saltbush can be established by either direct seeding or transplanting nursery raised seedlings. Direct seeding is the most cost effective way of establishing saltbush plantations, however slow germination and poor seedling establishment have limited widespread adoption of this technique. Seeds are very small and germinating seedlings are highly susceptible to drought, salt, competition with weeds and insect attack. In fact, direct seeding has been mostly unsuccessful on commercial scale plantings in New South Wales.

Planting saltbush seedlings (usually purchased as nursery stock) is more expensive than direct seeding, however establishment results are better and more reliable. Saltbush is relatively easy to propagate from cuttings.

Successful establishment of saltbush requires good preparation of the planting site. Weeds should be controlled in the spring before planting. Direct seeded plots will not require cultivation but if seedlings are being planted, the rows should be ripped (to optimise root penetration) and if the site is prone to waterlogging, mounded during summer. Scalping depressions may assist in water harvesting in dry areas.

Weeds should be controlled again after autumn and early winter rains, with sowing or planting taking place in late winter or spring.

Saltbush can be established in block plantings or as alley rows. Plant density in blocks is generally about 700-1,500 plants per hectare depending on the amount of rainfall. Plants are commonly planted three metres apart within the rows and at an intra-row spacing of 1.2 metres.

In alley rows, seedlings may be planted 2–4 metres apart within the row, there may be 3–4 rows planted together, and the width of the space between the multiple rows (the alley) will be determined by other uses of the paddock, including the size of machinery and vehicles that have to move up and down the alleys.

Careful thought should be given to access needs inside the saltbush belts, as if left uncontrolled stands can become impenetrable thickets in high rainfall areas or after wet summers and mustering animals can become difficult.

The establishment of blocks or rows of saltbush in several paddocks enables livestock extended access to saltbush without putting too much grazing pressure on individual saltbush stands. The benefits and feed value of saltbush are maximised when areas surrounding the saltbush block or the alley are sown with an understorey (legumes and annual or perennial grasses) at the time the saltbush stand is established. In alley systems, the alley may also be part of a cropping rotation.

State departments of agriculture and catchment management authorities can provide localised recommendations on establishment techniques.

The productivity of saltbush will be influenced by many factors, especially rainfall in summer, making it near impossible to provide general estimates. However, by way of example, annual average biomass production from a stand of 2,500 plants/ha, in a 400mm rainfall zone, would be about 1.6t/ha. In low rainfall zones or areas without significant summer rainfall 1 t/ha is a good estimate.

The rule of thumb published by NSW Department of Primary Industries is that the amount of edible material produced is about 4kg of leaf and twig per millimetre of rainfall per hectare. By comparison, lucerne in the same environment produces about 7 kg/mm rainfall/ha.

Weeds, pests and diseases

Saltbush seedlings are not strong competitors, so weeds in the planting rows should be well controlled before seeding or transplanting. Research in New South Wales showed that, once established, saltbush plants were more productive if weed control was maintained one metre either side of the plant.

In Mediterranean-climate zones where the weeds are annuals, they have little impact on saltbush productivity as they are dead during summer. Saltbush may improve growth of the understorey plant by providing shade and drawing nutrients from deeper within the soil.

In its natural dry and arid environment, old man saltbush has no significant diseases or pests. However, red-legged earth mite and lucerne flea can cause significant damage to young plants, especially seedlings. Control measures for red-legged earth mite should be undertaken before seeding or planting.

Attacks on mature plants by pests and diseases is occasional and related to seasonal conditions. Insect pests that have been found on old man saltbush include scale, leafhoppers, borers and several species of caterpillar. Local advisors or resellers should be consulted to determine the best control options for pest infestations. In many cases the plants survive without the need for intervention.

Vertebrate pests such as kangaroos, rabbits, hares and sulphur-crested cockatoos can destroy young plants so protection from these animals is essential in certain areas for successful establishment.

Infrastructure Requirements

The machinery required to establish saltbush plantings is widely available through contracting services. Landholders may use their own seeders or combines to sow saltbush seed, but experts recommend modifications to conventional seeding machinery for this to be successful. In most situations it would not be viable for a landholder to purchase a planting machine to transplant saltbush seedlings. These machines allow two people to plant up to 15,000 seedlings per day.  Costs can be reduced by not planting at high densities, 700 to 1,500 stems per hectare optimises biomass production per plant.

The ongoing management of old man saltbush does not require any specialised equipment or machinery that would not already be required on a grazing or mixed farming property. Once established pests are rarely a problem and the shrubs may respond to nitrogen fertiliser.

Harvesting & Processing

If good early growth of the saltbush stand has occurred, a light grazing can occur when plants are about 9–12 months old. Early grazing is important to increase the number of stems and reduce the development of wood. The first grazing needs to be managed carefully to ensure that the plants are defoliated quickly, but leaving 15% of the foliage remaining to ensure good recovery. Care should be taken to ensure there is no damage to the main stems and plants are not uprooted in sandy soils.

Established stands of old man saltbush can be grazed until 5–10% of foliage remains. Grazing to this level should be achieved in six weeks and then the stand is allowed to recover for 6–12 months.

If plants are not grazed adequately, they can become too tall and grow out of reach of the stock, and become more woody.

Old man saltbush is a summer-active plant with its primary growth period in spring and summer and markedly reduced growth during winter. The ideal grazing time will be in the late summer–autumn period when other pastures on the farm are depleted or passed productive maturity. However, if the plant recovers well and ample feed is available, it is essential that old man saltbush is grazed, even when other feed is adequate, to prevent the plant becoming woody. If plants become too woody they can be slashed back to a height of 30cm, and allowed to reshoot. Some producers have developed techniques to flatten the plants with farm machinery to encourage regrowth from the base.

Livestock new to old man saltbush will need a period to become familiar with the new feed. The supply of an alternative food source when stock are grazing saltbush is important to maintain well-balanced nutrition and liveweight. Saltbush should account for no more than 30–40% of the diet at any time.

It is important that old man saltbush is used as supplementary feed rather than the only feed provided to stock. While high in protein, sulphur, minerals and salt, saltbush is low in energy. The high salt content (>20%) will increase the animals’ need for energy, which must be provided by an alternative food source. Saltbush can have high levels of oxalate, leading to oxalate toxicity or calcium deficiency. The high salt content is likely to prevent animals ingesting a toxic dose of oxalate but pregnant and lactating animals may need additional calcium, especially if cereal grains are provided with the saltbush.

Stock grazing saltbush will need access to good quality (non-saline) water. Sheep on saltbush in hot conditions can drink 10 litres per day compared with two litres per day on a low salt feed.

There has been little effort made in developing harvesting methodologies for old man saltbush in Australia. The more standard and cost effective approach is to allow livestock to consume the green feed off the plant.

Markets & Marketing

Saltbush itself is not a marketed product. Rather, it is a component of a farming system that may contribute to increased profitability and sustainability of the farm business and environment. However, many graziers market their meat and consumers choose their meat on the basis that it is saltbush-fed.

Graziers claim that the meat of stock fed on saltbush has the marketable benefits of being leaner, richer and moister, and better tasting than meat from stock that have not had access to saltbush.

Research has been underway for several years to quantify these claims. A CSIRO meat technology update reported in 2012 that studies comparing saltbush-fed lambs to pasture-fed lambs, found no difference in flavour but a diet including saltbush appeared to increase levels of antioxidants in the muscle, making it possible that superior taste is associated with prevention of the off-flavour associated with oxidation. 

Research from CSIRO and the University of Western Australia reported in 2011 that meat from animals grazed on saltbush was a deeper red colour (due to higher vitamin E levels) and had a longer shelf life than meat from animals not grazed on saltbush.

Risks & Regulations

Risks/challenges

Grazing management is critical to achieve the full benefits of old man saltbush as forage. Undergrazed, it can become too woody, which decreases feed quality and allows the stems to grow tall and beyond the reach of stock. If grazing does not occur annually, the ‘stored’ leaves will be dropped if the plant gets water stressed through autumn.

Saltbush alone does not provide a balanced diet. While grazing saltbush, livestock should also have access to other sources of feed such as grain, pellets, hay, crop stubbles or understorey pasture. It is important that saltbush only constitutes 30–40% of the animals’ diet, if liveweight and general wellbeing are to be maintained.

The foliage of saltbush contains high levels of salt compared with other fodder and forage species, so a supply of water must be available to grazing stock. A sheep on saltbush will drink as much as 10 litres of water per day.

The risk of old man saltbush becoming a weed in eastern Australia has been determined as negligible due the widespread natural distribution of the plant and widespread introduction of the plant to other regions, including in Western Australia.

Regulatory considerations

There are no regulatory considerations specific to growing saltbush.

Publications

Publications/information

Saltbush Website information, Department of Agriculture, Fisheries and Forestry, Queensland (2011)

Saltbush for saline land Agnote AG1294, Department of Environment and Primary Industries, Victoria (2009)

Saltland pastures for South Australia A manual for the selection, management and evaluation of saltland pasture systems (2007)

Plants that grow on saline land Department of Agriculture and Food, Western Australia

Bladder saltbush, Department of Agriculture and Food, Western Australia

Silver saltbush, Department of Agriculture and Food, Western Australia

Getting the best from old man saltbush Agfact P2.5.43, NSW Agriculture (Department of Primary Industries, New South Wales) (2004)

Other resources

Sheep and saltbush thrive in the dry article (2013) on the website Farming Ahead Online

Review of High Priority Species for Woody Biomass Crops in Lower Rainfall Southern Australia – FloraSearch 3b Saltbush chapter in RIRDC report (2009)

Industry Bodies

There are no industry bodies specifically concerned with saltbush. Information about establishing and managing saltbush, as forage or for land rehabilitation, is readily available from state departments of agriculture, land management agencies, catchment management authorities and private advisors.

Image Gallery

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Saltbush

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Saltbush after four years

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Sheep grazing on saltbush

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Saltbush foliage

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Growth variation in paddock of old man saltbush