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Corangamite Region   'Brown Book'   - How to optimise your soils to enhance productivity
How do I best manage salinity on my farm?
Most relevant to cropping and grazing industries
Key Points
Understanding the problem
Managing the problem
Other related questions in the Brown Book
Resources
References

Source: DEPI Victoria
Key Points
  • Saline land is often an under-utilised resource, which has potential to grow pasture for summer weight gains for stock
  • Sowing adapted pasture species into mildly saline land can increase carrying capacity 2 to 4-fold

  • For small areas of saline land, or where land is strongly saline, it is preferable to fence the area separately and manage to encourage native summer-growing species
Understanding the problem
Why is it important to me as a farmer?
  • Salinity has a negative impact on the productivity of agricultural land
  • It is estimated there is more than 8,000 ha of land affected by salting in the Corangamite region, with the majority of this area on private land (Dahlhaus et al. 2005)
  • This land is primarily used for grazing and broad acre cropping, where salinity is reducing potential yields by as much as 90%
  • These areas typically have carrying capacities of less than 5 DSE/ha, and are dominated by undesirable plants such as barley grass and spiny rush
  • Yet with appropriate management, carrying capacities on some saline areas can be increased 2 to 4-fold
  • Stock can gain weight during summer, because high water tables allow pastures in saline areas to remain green while other pastures are dry
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How and why it occurs
  • Salinity usually refers to a significant concentration of mineral salts in soil or water as a result of hydrological processes
  • Salinity accumulates through salinisation, which is the process by which land or water becomes affected by salt
  • Salinity appears in the Corangamite region as either saline land, saline wetlands or as changes in water quality in our waterways and water storages
  • Land salting occurs through the accumulation of salts in the root zone and on the soil surface, usually by the evaporation of saline groundwater from shallow watertables
  • Land salting is the most obvious manifestation of salinity in the Corangamite region. There is an estimated 17,250 ha of land salting, occurring at 1,500 locations in the landscape (Dahlhaus et al. 2005b)
  • In some landscapes, the processes that cause salinity have been present for many hundreds or thousands of years, resulting in the formation of salt lakes and salt pans that are considered primary salinity sites
  • However, in many landscapes salinity processes have been induced as a result of changed land-use or water-use, resulting in the emergence of secondary salinity
  • It is these secodary salinity sites that are a concern to farmers in the region
    Figure 1 - Mapped salinity in the Corangamite Region. - Source: CCMA Soil Health Strategy    [View larger image] 
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How to recognise it in the paddock
  • The most common way to recognise soil and land salinity is by looking at the plants and condition of the soil
  • In agricultural land where secondary salinity has developed, the most common vegetation indicator species are Buck’s-horn Plantain, Water Buttons and Sea Barley Grass
  • Different collections of plants at a single site can be used to gauge the amount of salt present. There are generally five classes of severity that are used:
    • S0 (Non-saline) – no vegetation appears affected by salinity and a wide range of plants are present
    • S1 (Slightly saline) – salt tolerant species are abundant, salt sensitive plants are affected, no bare ground or salt crystals
    • S2 (Moderately saline) – salt tolerant plants dominate, salt sensitive plants are noticeably affected, small patches of bare ground and salt stains may be seen
    • S3 (Highly saline) – only salt tolerant plants survive, larger areas of bare ground, some salt stains and salt crystals in summer
    • S4 (Extremely saline) – only one or two species of salt tolerant plants survive, extensive areas of bare ground with salt stains and salt crystals evident
    Figure 2 - Slight salinity at Pittong. Spiny Rush and some deterioration of pasture is evident – Photo CCMA    [View larger image] 
    Figure 3 - Moderate salinity at Inverleigh. Salt tolerant plants abundant and the land cannot be cropped – Photo CCMA    [View larger image] 

    Figure 4 - High levels of salinity at Mt Mercer. Salt tolerant plants dominate and bare ground is evident – Photo CCMA    [View larger image] 
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    Figure 5 - Extreme salinity at Werneth. Only a few very salt tolerant plants survive in the saline soil – Photo CCMA    [View larger image] 
  • Plant indicators of saline land:

  • Plants are the best indicators of salinity throughout the year. A paddock walk is a quicker and cheaper way of assessing salinity than soil testing or electromagnetic (EM) surveys

    • Buckshorn plantain
      • A low growing introduced perennial tolerant of flooding, waterlogging and moderate to high salinity
      • It is a good indicator of salt stress, having leaves of a dull grey-green colour at low salinity and dark red at higher salinity
      • Sheep will readily graze buckshorn plantain
    • Yellow buttons
      • An introduced annual plant tolerant of moderate to high salinity, flooding and waterlogging
      • They colonise disturbed areas
      • Yellow buttons are readily grazed by sheep in the vegetative phase, but after flowering starts in November, sheep prefer other components of the pasture

    • Sea barley grass
      • An introduced annual grass tolerant of mild to moderate salinity, but it also grows widely in non-saline areas
      • It is readily grazed by sheep until mid-spring, when it grows a spiky seed head
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Managing the problem
What is the best practice?

  • Traditionally, salinity management has focussed on either reducing the groundwater recharge or controlling the groundwater discharge. Recharge reduction usually occurs through the establishment of tree plantations, tree belts, or perennial pastures. In the Corangamite region it has had little impact to date
  • By contrast, discharge management has been more successful, with the establishment of salt-tolerant vegetation species, surface drains and subsurface drains
  • Saline land can be managed as pasture, to improve ground cover and maintain productivity
  • Separate fencing of saline land is the first step to improving the growth and utilisation of pasture. Unless the area is fenced, sheep tend to overgraze it
  • The next step is to either manage the native and volunteer species already present, or sow a new pasture
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How can you achieve this?
  • Native pastures for saline land
    • Better management of existing volunteer plants on saline land, including natives, is worth serious consideration when desirable plant species are already present and:
      • saline areas are too small to justify sowing and separate management
      • salinity is mainly moderate to high
      • the landholder has an interest in native pastures
  • Sown species for saline land
    • A range of introduced grass and legume species can be established as pasture on saline land such as:
      • Tall wheatgrass
      • Tall fescue
      • Balansa clover
      • Persian clover
      • Strawberry clover
    • Sowing pasture on saline land requires more planning and preparation than sowing pasture on any other land
  • Weed control
  • Fertiliser management
    • Pastures established on saline sites require adequate nutrition, either from the soil or from fertiliser, to achieve satisfactory production rates
  • Grazing management
    • During the first growing season of a tall wheatgrass pasture, grazing should be light until November, to ensure plants are well anchored
    • After this, the pasture should be grazed when it reaches a height of 15 cm, and grazed down to 3 cm
    • Rotational grazing, a small paddock size, and large mob sizes are necessary to maintain the pasture in a vegetative state
    • Small areas should be fenced and managed separately to avoid under or overgrazing
  • Control of spiny rush
    • Spiny rush is an introduced weed that grows on low to moderately saline land, and is not readily eaten by livestock
    • It can dominate saline and waterlogged areas, reducing the carrying capacity of those areas
    • Landowners are required to take reasonable steps to control it and prevent its spread
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Other related questions in the Brown Book


Brown Book content has been based on published information listed in the Resources and References sections below

Resources
References
  • Clarkson T, Department of Primary Industries on behalf of the Corangamite Catchment Management Authority (2007).Corangamite Soil Health Strategy 2007. Corangamite Catchment Management Authority, Colac, Victoria.
  • Managing pastures in saline areas (Chapter 10). Greener Pastures for south west Victoria (2006) – Department of Primary Industries, Victoria.
  • Salinity Training Manual Corangamite Catchment Management Authority.
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This project is supported by the Corangamite Catchment Management Authority, through funding from the Australian Government’s Caring for our Country

Page Updated: September 2013
Produced by AS Miner Geotechnical