Diagnosing salinity in cereals

Salinity affects growth by reducing plant root ability to extract water from the soil, and chloride toxicity. Salinity damage varies from season to season due to variations in soil salt concentration as waterlogging increases salinity effects.

Surviving plants appear to be limp and water stressed.
Barley seedling leaves are dull with yellow tips that die back.
Bare saline area with surviving plants dying prematurely.
Leaves have a harsh pale appearance

Primary salinity

  • These are heavy textured, highly alkaline and usually well-drained soils with high levels of salt in the subsoil.
  • Most common are morrell-blackbutt loams on the edge of major valleys or greenstone soil and Dowak clay in the Esperance mallee.
  • These soils yield well in wet seasons and the worst yielding soils in dry seasons.

Secondary salinity

  • Salinity has been caused by salt accumulation from saline watertables or seepages that have increased after land clearing.
  • Soils vary but are frequently duplex or heavy textured.
  • Salinity is frequently accompanied by waterlogging in autumn and winter, which greatly increased plant damage.

Contributing factors

  • In secondary salinity situations, waterlogging greatly increases the toxic effect from high salt content but yields are likely to be less affected if there is sufficient rainfall to leach salts away from plant roots.
  • Naturally saline morrel loam soils are well drained and produce excellent yields during wetter seasons but yield very poorly during dry seasons due to accumulated salt in the subsoil.

 

What to look for

    Paddock

  • Moist bare patches where seed has failed to germinate or seedlings have died.
  • Patches of stunted and apparently water stressed or prematurely dead plants in areas subject to salinity.
  • Most crop weeds will also be affected with the exception of salt tolerant species.
  • Salt crystals may occur on dry soil surface.

    Plant

  • Plants have a harsh droughted appearance, and may be smaller with smaller dull leaves.
  • Old leaves develop dull yellow tips and die back from the tips and edge.
  • Heads are smaller with small grain.
  • Plants die prematurely.
  • Root growth is reduced, and may be brown and poorly branched or die if the plant is also waterlogged.

What else could it be

Condition Similarities Differences
Diagnosing seedling fertiliser damage in cereals Causes poor germination Plants that survive fertiliser damage will recover.
Spring drought, soil acidity, boron toxicity, hostile clay loam to clay subsoil and seedling root damage
Cause early plant death and shrivelled grain Causes can be determined by the soil type and location.

Management strategies

  • Naturally saline soils cannot be ameliorated but managed according to season and their capability.
  • Engineering solutions such as drainage may be possible for secondary salinity but must be assessed on a site by site basis.
  • Barley is the most salt tolerant cereal, but it has poor waterlogging tolerance.

How can it be monitored?

Soil test
Soil test
  • The salinity status of a soil can be assessed from indicator plants, measuring the salt concentration in soil samples or with electromagnetic-induction instruments or by measuring the depth to a saline watertable.

Where to go for expert help

Richard George
+61 (0)8 9780 6296
Page last updated: Thursday, 3 December 2015 - 11:25am