Native shrub offers dining option in drier months

Farmers may be able to ensure their sheep have continuing feed during Australia's long, dry summers thanks to a model which can forecast the growth of a particular native shrub.

CSIRO researchers have developed a farming systems model that includes a perennial shrub known as old man saltbush (Atriplex nummularia Lindl.).

The model, which predicts shrub growth, can be used to strategically address the feed gap for livestock, particularly in low rainfall areas.

Dr Andrew Smith says old man saltbush, and other forage shrubs like it, are a viable option for farmers during times when other feed options are scarce, such as during drought or at the end of summer.

"When there is little available for grazing, old man saltbush provides a useful solution," Dr Smith says.

"Although it is a slow growing plant it can be used to sustain livestock through the summer and can complement annual plant systems in areas with dry summers."

Old man saltbush is native to many parts of Australia and has been used in agricultural farming for many years.

Model works with existing framework

Dr Smith says considering the increasingly variable climate Australia is experiencing, now is the perfect time to rethink our farming systems and make sure that they have the flexibility and resilience required for sustainable farming.

"We need to rethink our farming systems by increasing the roles for these shrubs; we should be using what we have available to us," Dr Smith says.

The new forage shrub model works in the Agricultural Production Systems Simulator (APSIM) framework which is a suite of modules that allow the simulation of a number of agricultural systems

APSIM can simulate biophysical processes in a diverse range of farming systems, and can be used to address the economic and ecological outcomes of management practices in the face of climate risk.

Researchers collected data from two field experiments in Waikerie, South Australia, to ascertain various parameters and to verify the model's performance.

"Our model adds to the APSIM library of tools for planning and designing farming systems where grazing is important," Dr Smith says.

"It gives farmers the information they need to predict old man saltbush's regrowth after grazing across different soil types and climate systems over the long term."

Local CSIRO researchers are also developing new lines of forage shrubs with an improved nutritional content.