Exploring the future of native forage shrubs
From the November 2008 edition of Agriculture Today.
Possible uses
Different ways forage shrubs might be used in a farming system:
- Targeting marginal areas where crops or pasture are unviable and a feed gap exists
- As alleys or blocks of shrubs in cropped paddocks
- Where a farmer wants to reduce the use of supplements or buying in feeds such as grain or hay
Few perennial forages can fill the autumn-summer feed gap in most low rainfall farming areas.
However, shrubs have the potential to do this, so a new evaluation trial is exploring the potential of native Australian shrubs for low to medium rainfall (300-500mm) farming systems.
Shrubs can provide other benefits - drought tolerance, high protein content, ability to store carbon, use water at depth, reduce soil erosion and, in some cases, grow in saline conditions.
The native forage shrub evaluation trial, called Enrich, consists of 50 species and 4700 plants and has been established at NSW Department of Primary Industries’ Condobolin Agricultural Research and Advisory Station as part of a Future Farm Industries (FFI) CRC project.
According to NSW DPI agronomist and FFI researcher, Peter Jessop, rangeland graziers and many farmers already know the benefits shrubs offer livestock - fodder, shade and protection from wind and rain.
To some degree, native fodder shrubs such as Old man saltbush, Rhagodia and introduced Leucaena and Tagasaste have already been incorporated into Australian farming systems but there is the potential to make use of others.
"While shrubs often contain high protein levels, they vary in their digestibility," Mr Jessop said.
"They often contain undesirable compounds, such as salt and oxalates in the case of saltbushes and tannins which can reduce a shrub’s grazing value."
"This means that supplements or other feeds such as hay or grain or, where feasible, complementary herbaceous pastures need to be fed simultaneously with shrubs to counter the imbalance and provide a balanced diet.
"These extra inputs can however reduce the economic benefit of using shrubs in a grazing system."
Traditionally the majority of shrub plantations have consisted of one species.
This project is exploring the possibility of combining shrubs that complement each other and is also evaluating the contribution that lesser known or previously unevaluated shrubs might contribute to more robust and productive shrub systems.
"For instance, one type of shrub might contribute high biomass and protein while another might contribute to digestibility and desirable rumen fermentation patterns," Mr Jessop said.
He said Condobolin was selected for the focus of the main NSW shrub evaluation because it represented a large area of the State’s medium rainfall mixed farming zone.
It is one of three main evaluation sites in South Australia, NSW and Western Australia, with data recorded from these sites being complemented by 11 other smaller sites across the southern States, established in partnership with various regional groups.
The trial shrubs have been selected from an intensive screening of more than 60 species for biomass production, nutritive value for livestock, and bioactive effects on rumen micro organisms and gastrointestinal parasites.
They have come from two project planting sites in South Australia and Western Australia over the last three years.
Mr Jessop said Enrich was the first project in Australia to evaluate so many potential forage shrubs for so many characteristics at the same time and in so many locations across southern Australia.
Contact Peter Jessop, Dareton, (03) 5019 8407.
