Saltbush's role in Carbon Grazing
After years of following and being involved in the saltbush debate, my one wish is that the extreme positions would disappear. Saltbush is over-promoted by some as a wonder plant and completely under-valued by others. The truth is, it should be seen as part of a balanced landscape or a complete animal production system, and nothing more. It is true that saltbush is a unique plant in some ways, but that does not make it a better plant than others. What has to be utilised is this uniqueness that allows it to make specific contributions that other plants can not make, such as handling salt or low oxygen levels due to low carbon levels.
Saltbush coming back into favour
After many years of being misunderstood in so many quarters, it would appear that the role of perennial saltbushes and the contribution they make to carbon processes is now being better understood. This is leading to increasing acceptance of their importance.
The Federal Government has recently funded the new $34.5 million Future Farming Industries (FFI) Cooperative Research Centre to research different farming systems based on perennial plants to improve profits, combat a variable and changing climate, fight salinity and generate new regional industries. Saltbush is one perennial plant the CRC will consider closely. A flora search identified saltbush as one of the shrubs having the most to offer in terms of increased profits and landscape reconstruction as well as bio-energy potential.
Moving away from the narrow perspective of Old Man Saltbush
Saltbush has been promoted in a lot of literature as being a living haystack for droughts. This role of saltbush was clarified earlier as really meaning it is a long term protein source, not a complete fodder supply. Saltbush is a management tool, and its drought role should be seen as only one of the many contributions it makes to a rural operation. It does have unique characteristics that allow it to contribute to other landscape processes, such as salinity control and regeneration of badly degraded country.
In degraded country, the secret is to get the first plant to grow to initiate the carbon cycle then other plants will follow as carbon levels increase and encourage further germination. Introducing the perennial edible shrub, Old Man Saltbush (OMSB), is acknowledged by CSIRO rangeland scientist Dr David Freudenberger as the catalyst for the regeneration of degraded soils low in carbon. The drought resistance, water use efficiency and ability to handle low oxygen levels, of OMSB allows it to establish, via seedlings, in soils with a bad water cycle due to low carbon levels.
Geoff Chase "Wiatara" Trangie NSW, was taking a big picture approach when he said to me. "The biggest cause of moisture loss in his area is due to wind. The whole landscape can not function without water. Farming country needs saltbush planted in rows to lift the wind. In dry times this will also help stop wind causing soil erosion."
Geoff is supported by Peter Milthorpe, one of the acknowledged authorities on saltbush in Australia who states, "With good ground cover and grazing management, saltbush intercepts and retains more rainfall than do shrub-free areas because it reduces wind velocity and water evaporation from the topsoil."
Seeing OMSB as a management tool is a paradigm shift for those who see it solely as a drought reserve. OMSB is drought resistant, frost resistant and not eaten by kangaroos, therefore it is always available to provide rural operations flexibility and more options. Using it for resting pastures after a dry spell when good rain arrives, is a perfect example of the paradigm shift away from seeing it strictly in a drought role.
Some people who have never run a rural operation, are inclined to focus on the straight kg production of saltbush and then benchmark it against grass. They overlook the commercial outcomes of having options when the grass has failed. One of its roles is to buy time to allow an organised exit from droughts. Used correctly, it allows stock to be sold into the fat market, rather than the depressed store market. This is an important option when it is established that the dry spell is actually the start of a drought. The landscape also benefits when animals are sold, instead of being held due to their low sale value.
Trials have been conducted with cattle on saltbush to determine how much less grain is needed versus a straight feedlot. The outcome was that only 20% of normal grain rations were required. This could be an advantage in the future if grain prices rise as a result of ethanol production. The energy in a 20% ration is able to overcome the deficiency of energy in saltbush. The other issue is only having to transport 20% of the grain to establish a temporary feedlot.
Quantifying saltbush's commercial contribution
Back in the mid 1980's I decided to quantify the commercial contribution saltbush was making to my rural operation in a dry year. There was one paddock that had much more saltbush in it than the rest of the property, so I decided to benchmark the production of this paddock against the rest of the property. There were cattle on the property, but the calculations were based on comparative analysis of the financial performance of breeding ewes.
The gross production of the animals in the paddock with more saltbush was 30% higher than the rest of the property. This would have been a higher percentage if the analysis was translated into profit increase.
In a private trial, prior to the research project, I achieved an extra 30% of lambs by lambing in a saltbush plantation. The outcome had nothing to do with the quality of saltbush, it all related to the ewes being contained in a small area and the lambs not mismothering, as happened to their counterparts in a large paddock.
Carbon storage by saltbush
In 2004 Chris Mitchell the CEO of CRC for Greenhouse Accounting, informed me that little was known on the real impact of saltbush on carbon storage. One piece of positive evidence he was aware of, related to a 5 year-old stand of Old Man Saltbush. In the grass only area measured, 68 tonne/H of carbon was measured, while the area which contained both saltbush and grass, 80 tonne/H was recorded.
Water use efficiency
Trees and shrubs with light coloured, grey or grey green leaves are better at reflecting sunlight and are usually more water efficient than those with dark green leaves. This partly explains the known water use efficiency of saltbush. Their leaf structure also reduces transpiration. Increasingly, with the issue of climate change, the key will be to breed plants that use less water, and ascertain how to best incorporate efficient plants into new farming systems. The newly created FFI CRC will be researching the development of new perennial farming systems, and Old Man Saltbush is one of the perennials they have identified as having potential.
Seeing saltbush as a companion plant
Old Man Saltbush while having a similar role as trees in the landscape, due to its deep roots, is far more compatible with grasses than many species of trees
Perennial cropping
With rising fuel prices and climate change, there will be a shift towards perennial cropping in some areas. When designed correctly as a production system saltbush plantations fulfil this role. The crop has to be managed, but it does not have to be planted each year.
Using a perennial plant with high water use efficiency and very deep roots is the opposite to current cropping based on annuals. There is also the added efficiency of using a C4 photosynthetic pathway to supply protein under marginal conditions. Grasses and other understorey will be critical components of this new farming system, with the saltbush enhancing their performance through lifting wind and shading, not just as a reliable protein source. The protected perennial grasses will enhance soil health which will make greater sub-soil moisture available to the deep rooted saltbushes over time. It is a win-win system.
Pasture cropping could be included in the pasture component between the saltbush rows. This would add to the total energy capture of the system and the overall quality of production. Looking to the future, the shrub component would oscillate between protein production and bio-energy production. Perennial cropping is a shift back to complexity in production systems (i.e. the way nature designed things to happen).
Muscle wasting and vitamin E
CSIRO research has revealed that there are higher levels of vitamin E in the meat of sheep grazed on saltbush. Low vitamin E levels in dry summer feed can lead to a muscle wasting condition in sheep known as "nutritional myopathy".
Vitamin E is a powerful antioxidant and has been shown to improve stability and shelf life of beef.
Saltbush enhances bypass protein in ruminant animals?
While an animal production expert considered it possible that saltbush could enhance bypass protein production, when I raised the issue with him in 1997, it has never been researched by the scientific community. The possibility is that salines actually enhance the production of bypass protein from a mixed diet as the season deteriorates, and saltbushes become a larger percentage of the diet. In a trial by the CSIRO where they fed sheep either grass or Old Man Saltbush only, they concluded that two thirds of organic matter of grass pasture is digested in the sheep's rumen (fore-stomach), with the remainder digested in the lower gut (4th stomach). That compares with about one third for Old Man Saltbush leaves in the rumen. One accepted way to increase bypass protein is increasing the outflow from the rumen to wash out protein before it is fermented. Salt increases the outflow from the rumen. Some protein is not available to the rumen microbes with the early emptying of the stomach. On the other hand, there is a larger volume of food passing through the rumen.
Low Cost Saltbush Technology
After conducting a $272,000 Drought Regional Initiative project on how to incorporate Old Man Saltbush into a rural operation, with an emphasis on using it for resting pastures to allow them to regenerate following rain, it became obvious to me that cost of establishment had to be reduced. Others raised the same cost issue at a range of other events.
We have concentrated on the bare-rooted method which has reduced the cost of seedlings to 20% of those produced by commercial nurseries. The new approach will ensure that seedlings are close to where they are needed for planting. The on property nurseries will allow thicker stemmed seedlings with higher energy reserves to be produced and guarantee the availability of seedlings whenever opportunities present.
A one-pass transplanter which prepares the seed bed as well as transplant the bare-rooted seedlings was developed. This planter is now being modified to allow planting of seedlings under marginal conditions, thanks to NLP funding. To allow grass to be retained between the rows of saltbush, a special ripper has been developed.
Saltbush grows on past rainfall, while grass grows on future rainfall. My point, it is easier to predict the past than the future.
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