National project tackles subsoil constraints

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Photo of soils

Soils high in sodium or magnesium tend to disperse when wet, causing poor water infiltration and root growth, and surface crusting resulting in reduced plant emergence.

PHOTO: Brad Collis

A new GRDC-funded research project running until 2020 will focus on improving diagnostics and management strategies for subsoil constraints at a regional and paddock scale


Australia has the most extensive area of sodic soils in the world. More than 60 per cent of the nation’s 20 million hectares of cropping soils are considered sodic or magnesic.

Soil sodicity in surface and subsurface soils compromises grain yield by as much as 50 per cent due to its negative effects on soil dispersion, water infiltration, crop establishment and root growth.

A new GRDC research project, which will run until 2020, will bring together Australia’s leading experts to identify, develop and demonstrate improvement management strategies for sodic and magnesic soils across Australia’s grain-growing areas. Strategies to be investigated include crop selection, soil ameliorants and tillage techniques.

The project will also work closely with plant-breeding researchers to identify tools to help select for chickpea and wheat genotypes tolerant of dispersive soils.

After collating and reviewing available information on known and novel management solutions for sodic soils, the project team will evaluate these methods across each of the GRDC growing regions.

The project will also test simple on-farm identification tools for diagnosing dispersive soils and extend these methods to industry.

Sodic soils can be broadly classsified into three categories according to pH:

  • acidic-sodic soils: pH less than 5.5 in topsoil with subsoil highly sodic and magnesic;
  • neutral-sodic soils: pH 5.5 to 8.0 with structural problems due to dominance of chloride and sulfate ions; and
  • alkaline-sodic soils: pH greater than 8.5 with bicarbonate and carbonate ions dominating and causing dispersion and toxicities (boron and others).

Each category has different structural issues and as such management solutions need to be tailored accordingly.

More information:

Dr Ram Dalal, Queensland Department of Science, Information, Technology and Innovation,
07 3170 5766,

ram.dalal@dsitia.qld.gov.au

Previous:

Acid soils on the rise across NSW

End of Ground Cover Supplement: Soil constraints
Read the accompanying Ground Cover here:

Ground Cover issue 118: Sept-Oct 2015

GRDC Project Code DAQ00200

Region National