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Exhaustive endeavour to relieve soils headache

Enlisting excavation equipment, a team of researchers are re-engineering soil profiles on Mark Pearce’s property at Tarin Rock.
Photo: Anvil Media

Innovation is the backbone of Australian farming systems, often driven by growers who pioneer cropping practices. But with the support of GRDC, Australian growers can push the boundaries of crop productivity still further.

Mark Pearce, who farms with his wife Lisa at Tarin Rock 300 kilometres south-east of Perth, knows this and has provided an area of his property for a radical experiment to pursue solutions to his main farming limitation.

“The nature of our soils is our major limitation as we have varying constraints across the entire 3000 hectares we crop,” he says.

Mark is a member of the western region GRDC Grower Network, and he is also a member of the Soils Constraints – West initiative since it began in 2015, so has been able to tap readily into the latest research in this space.

“We have tried a number of different approaches to ameliorating our soils including reefinating – crushing rocks, cultivating with Swifter discs – to deal with non-wetting soils – and ripping. But none of these have been effective so we are really keen to find a solution,” he says.

“We have a fair proportion of duplex soils, which should be our more productive soils but aren’t because they are prone to waterlogging as well as being acidic in the top 20 centimetres and sodic at depth.”

So as part of a broader $42 million collaborative venture between the Western Australian Department of Primary Industries and Regional Development and GRDC, Dr Gaus Azam’s team is re-engineering the soil profile of a trial area of the Pearces’ property to determine what can be achieved for plant production in this water-limited environment.

The profile has been excavated to 80 centimetres at 10cm increments and the layers separated. Up to 10 different treatments have been tested, with increasing levels of ameliorating power to the various layers, and then they have been replaced.

If we can get crop roots deeper into the profile where we know there is moisture available, as well as potash, it may also potentially reduce our fertiliser use.

Mark has sown the barley variety Spartacus CL (PBR) across the trial plots using his own equipment on tramlines to avoid compacting the plots. Four further years of crop production will be monitored on the site.

“We have had a very good season this year with up to 450 millimetres of rain, so as the surrounding barley became waterlogged, we have seen the treated trial plots flourish,” he says.

“We will be keeping livestock off this trial site to avoid compaction issues, but it will be interesting to monitor whether the soil remains friable or if it begins to settle and compact over the trial period.”

If significant crop productivity benefits can be demonstrated from this radical re-engineering, Mark says he is hopeful that the necessary machinery innovation will follow.

Read: The great dig to re-engineer soils.

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