Sustainable Dryland Farming in the Mallee of South Eastern Australia

1
Sustainable Dryland Farming in the Mallee of
South Eastern Australia

• John Leys
• Centre for Natural Resources
• Department of Infrastructure, Planning and
  Natural Resources

2
Acknowledgments
3
Mallee Sustainable Farming Inc.

• The goal of the project is to increase the
  adoption of sustainable and profitable farming
  practices in the Mallee of South Australia, New
  South Wales and Victoria.

4
Sustainable Agriculture in the Mallee

• Environmentally and agriculturally sustainable
  farming is possible in the Mallee because
• Increased agricultural production has
  environmental benefits, ie increased water use
  and greater ground cover for erosion control
• Low rainfall makes water balance possible
• Deep sandy soils allow deep rooted perennials to
  chase deep drainage
• Recent research has provided a good understanding
  of the physical system

5
Study Area Location

• 4 million ha of land spanning the states of in
  NSW, Victoria and South Australia.

6
The Environment

• Mediterranean climate
• Low rainfall (225 - 350mm)
• Sandy aeolian soils prone to wind erosion
• Originally perennial native vegetation - trees,
  shrubs and grasses
• Currently dominated by annual winter crops
  (cereals and legumes) and introduced pasture

7
A Feature of the Mallee

• The Long Fallow
• Paddock is kept weed free for 6 to 9 months prior
  to the winter crop
• Aim
• to store soil water from the previous Spring and
  Summer until late in Autumn
• mineralise nitrogen
• level the soil and remove excess ground cover to
  allow sowing

8
Long Bare Fallow

• Prone to wind erosion
• Prone to deep drainage of soil water and
  resultant salinity

9
Wind Erosion

• Causes
• long, bare fallow (9 to 6 months of weed free)
• too many cultivations (greater than 3 per crop)
• too many stock for too long
• sandy soils
• ground cover and soil aggregation levels less
  than 50

10
Wind Erosion

• Solution
• no long fallow on sandy soils
• conservation farming methods, maintain cover and
  soil aggregation
• continual cropping or pasture with gt 50 cover

11
Salinity

• Causes
• Salt at depth in soil
• Low water holding capacity of sandy soils (35 mm
  PAW to 1 m depth)
• Deep drainage of rainfall past crop rooting depth
  raises water table, brings salt to surface
• Deep drainage greatest on sands, during wet years
  and during fallows

12
No Deep Drainage
13
Deep Drainage
14
Deep Drainage Events
15
Salinity

• Solutions
• No fallow period on sandy soils - reduce deep
  drainage
• Maximise crop and pasture growth - increase water
  use
• Use deep rooted perennials after deep drainage
  occurs - to use deep drainage water

16
Deep Drainage
17
Elements of the Sustainable System

• More crops more water use greater ground
  cover better soil health less nitrate
  leaching
• More crops offer increased profitability
• Less long fallow on sandy soils less wind
  erosion less deep drainage
• Understanding of the agricultural system by
  landholders

18
Recognition of Success

• Banksia Environmental awards - runner up 2001
• National Landcare winner - 2002
• Various State Landcare awards for the group and
  its members

19
Conclusions

• There has been an increase in the adoption of
  sustainable and profitable farming practices in
  the low-rainfall Mallee through a research /
  action learning model.
• Better matching of farming system to the
  biophysical limits of the landscape results in
  Mallee farming systems that are much more
  profitable and sustainable.

20
Mallee Sustainable Farming Inc.Sharing,
Learning, Doing