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.

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.

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.

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.

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.

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.

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.

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)

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.