Overcoming constraints to the profitability of cropping systems on ironstone gravel soils within the Southern cropping region of Australia – Phase II

Providing new information on water and nutrient use efficiency of ironstone gravel soils to better inform their management.


Key Messages

  • Ironstone gravel soils are an often-underperforming soil type present across Australia’s Southern cropping regions, concentrated in the croplands in the southwest of Western Australia and the Eyre Peninsula and Kangaroo Island in South Australia.
  • Phase I of this research provided fundamental knowledge of gravel composition, mineralogical structure and interactions with water, nutrients (phosphorus/nitrogen) and microbes.
  • Iron-dominant gravels bind the most phosphorus, making it less available to plants. This contrasts to silica-dominated gravels, which are more porous supporting greater exchange of water and nutrients.
  • State-of-the-art imaging techniques allowed the visualisation of water and nutrient dynamics in gravels from across WA and SA.
  • This Phase II program of research focuses on solutions to the problems identified in Phase I, building on this knowledge to develop gravel-type specific management strategies for increasing water and nutrient use efficiency in the next few years.


The distribution of gravel soils across Australia’s southern cropping zones is well known, with 24 % of land used for crop production in southwestern WA containing gravel and further gravel regions on the Eyre Peninsula and Kangaroo Island, SA. Despite this, gravel soils do not reach their water-limited yield potential (kilograms grain per millimetre of available water). This is thought to be linked to the reactivity of gravel surfaces and their internal pore networks influencing water movement and fertiliser use efficiencies (especially phosphorus and nitrogen) in the soil profile. Gravels vary in composition across the landscape due to differences in their parent geology and soils.  As such, there is a need to understand this variability and its consequence on water and nutrient interactions.

The focus of Phase I of this research was to generate the necessary physical, chemical, mineralogical and biological data to understand the kinetics of how gravel (type, size, depth) interacts with phosphorus, nitrogen and water use efficiency. The aim was to assess whether simple relationships could be derived and used to predict the capacity for phosphorus fixation and nitrogen uptake in gravel soils. The new knowledge generated in this project provides the foundations to develop fertiliser recommendations and management strategies for gravel soils in phase II.


This project is supported by a Grains Research and Development Corporation (GRDC) Investment. In-kind support was provided by Murdoch University, The University of Western Australia, The Centre for Microscopy, Characterisation and Analysis (UWA), Bangor University and Queen’s University Belfast.



Dr. Francesca Brailsford

SoilsWest, Murdoch University

Prof. Daniel Murphy

SoilsWest, Murdoch University

Dr. Rowan Maddern

GRDC Manger Soils and Nutrition - West

Research Team

  • Francesca Brailsford (SoilsWest, Murdoch University)

  • Frances Hoyle (SoilsWest, Murdoch University)

  • Richard Bell (SoilsWest, Murdoch University)

  • Talitha Santini (SoilsWest, The University of Western Australia)

  • Matthias Leopold (SoilsWest, The University of Western Australia)

  • Martin Saunders (CMCA, The University of Western Australia)

  • Peta Clode (CMCA, The University of Western Australia)

  • David Mainwaring (Murdoch University)

  • Davey Jones (SoilsWest, Murdoch University)

  • Emily Cooledge (Bangor University)

  • Gavan McGrath (The University of Western Australia/Murdoch University)

  • Panagiotis Manesiotis (QUB)

  • Brett Masters (PIRSA)

  • Lyn Dohle (PIRSA, KI)

  • Daniel Murphy (SoilsWest, Murdoch University)