Scientific Name: Atriplex nummularia
Old Man Saltbush is an interesting, multi-facet plant, of great use to the farmer and the environmentalist alike.
It is a member of the Chenopodiaceae family of plants, and is a halophyte — a plant that can grow in salty soil. It is distributed worldwide, occurring commonly in warm, temperate regions, and arid, dry regions.
Old Man Saltbush is a multi-stemmed shrub that can grow up to 2m in height & 3m wide. It is evergreen, frost resistant, and drought tolerant. It has grey, round-shaped leaves which are covered with minute salty scales. These deflect the direct rays of the sun off the surface of the leaves, keeping the plant cooler, thus allowing it to conserve water.
The plant has the unusual ability to accumulate higher than normal concentrations of salt in its leaves and roots. It has a robust root system consisting of a deep tap-root, additional vertical roots, 3 layers of lateral roots and a layer of special secondary hair-roots that lie just under the surface of the soil. This array of roots affords the plant the best opportunity to absorb ground water, while the surface roots specifically harvest the slightest moisture on the soil from the morning dew.
Due to the higher salt levels present in the cells of its roots, this plant is capable of absorbing, through the process of osmosis, the smallest amounts of water, or moisture, that might be present in the soil.
Commercial value as a fodder plant
This hardy plant is of great benefit as a fodder plant for the stock farmer, especially on farms in arid regions. Once established it requires little water to sustain itself. It can be grazed year long. Its deep root system draws up valuable minerals from the soil and makes them available to the grazers.
The leaves contain a natural bitter constituent — chenopodium oil — which reduces internal parasites in the stock. One further practical benefit of establishing this bushy plant as a fodder plant is that it promotes grazing removed from the surface of the soil where parasite eggs lie dormant.
The plant grows best in soils with a pH of 6 or higher. It does not
tolerate acidic soils. It will thrive in fertile soil, but can
easily be established in unproductive soil, or degraded soil, or in
soil with a high salt content. (More detail on this further on.)
PLANTING FOR GRAZING PURPOSES
Planning and spacing:
It is advised that the plants should be planted in rows which will make it easier for watering and the maintenance of weeds once the plantations are being established.
In poor soils:
Allow approximately 3,330 rooted cuttings (or seedlings) per hectare. Between-plant spacing should be 1m and between-rows 3m.
In very arid, dry regions with very low rainfall:
Reduce plant density to 2,000 plants per hectare, spacing them 1,5 – 2m between-plant, keeping the between-row distance the same, 3m.
In fertile soils, or in regions of guaranteed seasonal
Plant a double row of plants 1m apart & between-plant spacing 2m, with a wide between-row spacing of 4m apart.
If the bushes are to be used for grazing, camps / plantations should be established in fenced off areas to allow for rotational grazing – the more camps, the better.
Soil preparation & planting:
The soil should be well prepared to allow for optimum penetration of water to the sub-soil. Deep rip the rows 3 times, or dig individual holes at least 50cm deep, and loosen the soil. A light dusting of Lime can be worked into the soil.
When planting, gently firm the soil around the rootlets of the cutting / seedling to ensure there will be no air pockets on the rootlets, causing them to dry out.
Immediately after planting each plant should receive, by hand, 2 cupfuls of water (500ml), and then the same amount every day for a minimum of 2 weeks.
The plant should not be allowed to dry out at all during this establishment period, and if necessary a second watering should be given each day.
When it is evident that the plants are starting to grow, water can be applied every second day, using a pipe from a water-cart, or overhead irrigation, if you have this available.
Once the young plants are established they should be watered once a week until they can sustain themselves — you should be able to see that they are doing well (when new growth is visible). When the bushes reach 30-50cm high they can be pruned back by 10cm to encourage spreading. There is no need to apply any fertilizer.
Proper Utilisation of Old Man Saltbush for grazing:
When the Saltbushes are 0.8 – 1m high, which usually takes between 8-10 months in fertile soil, stock can be introduced to graze the bushes for the first time.
A large number of stock should be moved through the camp quickly — over a period of 2 weeks, maximum — for the first intensive grazing, allowing them to defoliate the bushes back to 10% leaf cover, or alternately, a 90% defoliation. This will encourage re-growth and spreading of the bushes.
Thereafter, if there are 4 camps of bushes the maximum grazing period should not be longer than 3 months, and the recovery period 9 months. If there are more camps the ratios change, and for example, if there are 13 camps, with a grazing period of only 2 weeks per camp, the recovery period will be 6 months and each camp can be grazed twice a year. By observing how quickly a specific number of your stock achieves the desired defoliation of the bushes you will arrive at the correct stock rate per camp.
If the plantation is irrigated the biomass per hectare will increase substantially, and the recovery time following grazing will shorten.
Rotational grazing will increase the plantation’s carrying capacity. A grazing system that includes Old Man Saltbush will carry 4 times more stock per hectare in the first year of grazing, and nearly 6 times more each year thereafter. In addition, a sensible stock farmer can increase the grazing potential of the camps by establishing highly nutritional grazing grasses between the rows of the Saltbushes. These camps will provide an exceptional fodder mix of carbohydrate plus a quality protein from the Salt bush.
It stands to reason that stock who are not used to grazing Old
Man Saltbush will need a period of familiarisation to get them to
graze it. At first they will avoid the plant, but once they have
eaten the surrounding food they will start grazing the bushes. At
all times ensure that there is adequate water at their disposal as
the saltiness of the leaves increases their need for water.
If the camps are not grazed regularly the bushes will grow too high for small stock, like sheep, to graze the upper twigs, and the plant will develop woody stems, and fewer useful leafy, soft branches. It will be necessary to prune the bushes back considerably to restore the camp to use.
Once the camps are in constant use the manure or droppings from the stock provide sufficient fertilizer to sustain the plants in the camp.
ENVIROMENTAL BENEFITS OF OLD MAN SALTBUSH
Due to its extensive root system this hardy plant can successfully be utilised to halt soil erosion. When established, the roots bind together and stabilise the soil, and prevent further wash-away during rainstorms.
- The presence of these hardy, dense, bushy plants minimises the impact of wind erosion on the surface of fragile, eroded, or denuded soils, preventing dust storms, and affording protection for pioneer plants to begin to take hold and re-populate the area.
- Hedges of Old Man Saltbush in stock camps provide welcome shelter for stock animals — shelter from harsh sun, driving rain, strong winds and icy cold winds.
- Hedges of Old Man Saltbush make attractive, easy to maintain general wind breaks around gardens, dwellings, settlements, and work areas — providing protection from driving wind, cold weather and fires, and providing permanent natural shelter and nesting places for birds, small mammals, and insects.
Returning fertility to the soil:
Due to its deep and extensive root system Old Man Saltbush draws vital nutrients from deep in the soil up to its aerial parts. These mineral rich leaves are constantly shed onto the surface of the soil, and decompose in situ, building up the nutrient value in the upper layers of the soil.
- This plant, which is capable of surviving in the poorest of soils, can be utilised to restore fertility to unproductive farmlands, turning them into commercially beneficial grazing lands.
- Degraded and damaged soils, such as mine dumps, can also be populated with this plant, in conjunction with others, for the process of rehabilitation.
Due to the high salt content throughout the entire plant, as well as the constant moisture content inherent in its leaves and stems, Old Man Saltbush does not burn easily. It can thus be purposefully utilised to cultivate a physical fire barrier in vulnerable areas. In this instance, dense hedges, several rows deep should be established. Once the bushes are established, the barrier they form ought to be high enough to prevent all but the worst wind driven flames from jumping the distance, wide enough to prevent radiant heat from harming the vegetation growing beyond the hedge, and high and wide enough to be an ember trap.
Drought resistant and "water wise":
Old Man Saltbush is an exceptionally good example of a drought resistant plant which requires a minimal amount of water to survive. It is therefore of great benefit for the stock farmer in arid regions who needs grazing material that will survive periods of drought.
SALT — a unique feature of the Saltbush — Salty soil and
Only 2 % of the plants of the world have the ability to grow in, or tolerate very salty soil. These plants are called halophytes. The Old Man Saltbush plant belongs in this category. It is capable of living in salty soil, because it has the ability to develop and maintain an elevated concentration of salt within its leaves and root cells. This then balances with its external environment, thus ensuring its survival in this hostile situation. It can grow in the very worst areas of salinity, provided there is no surface groundwater.
The Saltbush can, however, withstand being subjected to salt water, as long as it is no more than half the saline strength of sea water (25,000 parts per million). It can tolerate a situation of shallow flooding and water-logged roots periodically, but will definitely die back if there is inadequate drainage of this salty water.
The Saltbush plant can be utilised to desalinate and rejuvenate a problem area which is wet and salty. Many Saltbush plants should be planted close around the problem area, without planting them in water. Their roots will absorb the salt and equalise the salt content of the water and surrounding soil. After some time, more plants can be planted closer and closer to the source of the seepage until the whole area is under control. As the Saltbush is not a water-hungry plant, it will not have a negative effect on the ground water.
Old Man Saltbush belongs to 1% of the known plant species that uses a process called C4 photosynthesis or C4 carbon fixation.
Photosynthesis refers to a process that takes place in the leaf tissue of all plants. In the majority of plants, the process of photosynthesis is termed a C3 process because the cells which perform photosynthesis contain 3 carbon atoms. Those plants that perform a C4 photosynthesis, amongst them the Old Man Saltbush, have 4 cellular carbon atoms and they are considered to have a certain superiority in environmental conditions of high temperatures, high salinity, drought and low nitrogen. During C4 photosynthesis in these plants, the conversion of atmospheric carbon gas into plant material uses less oxygen, less water, fewer nutrients, and minimum destruction of its own living tissue during the process.
Old Man Saltbush is therefore one of the plants that has been identified by the United Nations Carbon Emission Trading Scheme to assist with the combat against global greenhouse warming and the sequestration of atmospheric carbon back into the soil. It has been estimated that Old Man Saltbush, once it reaches 3 years of age, will convert approximately 15-20 tons of carbon per hectare.
The Kyoto Protocol is an agreement which was made in 1997 at the United Nations Framework Convention on Climate Change. Most of the countries of the world signed this agreement and have committed to reduce the emissions of carbon dioxide and other greenhouse gases by whatever means possible.
Old Man Saltbush is listed as a no 2 alien plant in South Africa.
Plants listed as No 2 are plants with the proven potential of becoming invasive, but which nevertheless have certain beneficial properties that warrant their continued presence in certain circumstances. In the case of Old man Saltbush it has economical use as discussed above.
It is not against the law to plant any Plant listed as No 2 Alien plants — providing that the land user apply for a demarcation permit from the Department of Agriculture - to plant it primarily for a commercial or utility purpose, such as a woodlot, shelter belt, building material, animal fodder, soil stabilisation, medicinal or own consumption.
The conditions under which the plant is cultivated, have to be controlled; all reasonable steps have to be taken to curtail the spreading of seeds or vegetatively reproducing material outside the demarcated area, and all specimens outside the demarcated area have to be controlled.
Category 2 plants may not occur within 30 m from the 1:50 year flood line of water sources or wetlands, unless authorisation has been obtained in terms of the National Water Act of South Africa. The Executive Officer of the Department of Agriculture has the power to grant exemption from some of the above requirements.