Ripping into subsoil acidity – Update 2018

Managing subsoil acidity for improved crop yield

Ripping into subsoil acidity – Update 2018

Managing subsoil acidity for improved crop yield

Showing the Difference -


The issue

Holbrook Landcare Network (HLN) is one of four regions conducting trials as part of a GRDC project Innovative approaches to managing subsoil acidity in the southern grain region running from 2016 to 2019.

Several trial sites have been set up around Holbrook to run for three cropping seasons. Although acid soils can develop naturally, certain agricultural practices increase the rate of acidification. If left unmanaged acidification will degrade agricultural land and cause larger yield losses in the future.

Scientific plot trials have shown some materials and methods have promise to help combat the issue but this project takes those leads to the paddock to test them in real life situations.

The solution

NSW DPI field technicians, in consultation with local farmers who have been involved previously with deep placement of manures, developed and custom built a modified Grizzly deep ripper to correctly place the amendments for the trials.  It has the capacity to deliver 20 t/ha organic material and a roller system to compresses soil behind rippers and leaves a flat surface ready for sowing. Although it’s the type of machine that wouldn’t be viable or appropriate for every farmer to use, it’s been important that the material placement is done properly so we can see if there’s merit in investigating more efficient methods.

The machinery itself has been a great talking point for the project and a good platform for having discussions about how we could be doing things differently.

The impact

The research team led by NSW DPI principal research scientist, Dr Guangdi Li, has so far found a positive crop response to deep ripping and soil amendments in wheat, barley and canola at seedling and flowering stages.  Deep ripping with lucerne pellets produced more seedling dry matter and improved crop growth than surface liming and ripping alone.

Undertaking research on a working farm under variable conditions has provided its fair share of challenges for the researchers trying to make sense of the data, the Landcare Group maintaining the site and sharing the learning and the landholder seeing how the treatments fit into their farming system.  Only by combining the experiences of everyone involved are we likely to have good ownership and adoption of the project outcomes.

Please see Case study LLCI020-005 for the Project overview.

Key facts

  • Crop yields drop when soil pH falls below 5.0 in CaCl2
  • One site has a pH(CaCl2) of 4.6 at 10-20 cm depth
  • Total losses to agriculture approximately $900 to $1,585M/yr
  • Early results: clear crop responses to a variety of treatments

Project Partners