Pale deep sand re-engineering brings yield improvements

Much to gain: Research scientist Tom Edwards, technical officers Rachelle Desmond and Joel Kidd dig soil profiles for assessment of root abundance. Photo: Supplied.
Much to gain: Research scientist Tom Edwards, technical officers Rachelle Desmond and Joel Kidd dig soil profiles for assessment of root abundance. Photo: Supplied.

Research by the Department of Primary Industries and Regional Development has found significant potential for yield improvements through re-engineering pale deep sands.

Past field trials have demonstrated that topsoil water repellence can be effectively ameliorated by spreading and mixing clay through the top 300mm with a rotary spader.

However, pale deep sands face additional subsoil constraints including compaction and low cation exchange capacity, which prevent crops from reaching their full potential.

Research investigating means of overcoming these constraints will be presented at the 2020 Grains Research and Development Corporation Grains Research Updates in Perth.

Department research scientist Tom Edwards said the findings could provide the key to increasing and sustaining economic benefits of pale deep sands amelioration.

The research, with co-investment from the GRDC, sought to determine if crop production could be further improved on pale deep sands which had been ameliorated.

"The aim was to improve root growth and the plants' subsequent abilities to forage for water and nutrients later in the season," Mr Edwards said.

"We found significant yield improvements were possible when clayed and spaded treatments were ripped to about 40cm to reduce subsoil strength and increase root penetration.

"This highlighted the need to continue to monitor soil strength and water use efficiency after amelioration as re-compaction can occur through the use of farm machinery and cultivation processes, as well as naturally as the subsoil wets and dries."

The trial also tested the ability and benefits of introducing organic amendments and fertiliser to a 60cm soil depth using a chain trencher.

The process effectively incorporated amendments into the subsoil and improved root abundance, but benefits were only observed within the trenches that had been created.

Ripping with inclusion plates did reduce soil strength between tines and was also able to adequately incorporate chicken manure and fertiliser deep into the profile.

The 2020 GRDC Grains Research Update will be held in Perth on February 24 and 25, while regional updates in the weeks following.