The Soil Water Repellence Project

Exploring management options for ameliorating non-wetting soils in the West Midlands region.

Exploring key aspects of soil amelioration on variable soil types through diagnosing paddock scale soil constraints, identifying the most appropriate amelioration method(s) for the constraints and determining the economic advantage (ROI for the paddock) behind these methods.

Commencement: 2024 | Completion: 2026

Funding body(s): Grain Research and Development Corporation (GRDC)
Project Lead Organisation: The West Midlands Group

Background

Farmers across the Geraldton and Kwinana West Port Zones are faced with the significant, ongoing challenge of managing soil water repellence. The regions sandy soils are low in clay content and as a result, have a low surface area. Waxy substances that originate from plant organic matter when they decompose are left in the soil to coat the sand particles and over time, this process causes the soil to have reduced infiltration of rainfall. This leads to patchy crop emergence and lowers grain yield while also causing issues with weed management and fertiliser use efficiency.

Across the region farmers have successfully implemented a range of once-off soil amelioration strategies for the deep sandy soils where there are few physical obstructions to the use of deep tillage equipment like mouldboard ploughs, rotary spaders, and deep rippers. This has led to an increase in grain yield and increased profitability which has been consistent for every year following soil amelioration (Planfarm 2024). While this approach has been successful on the deep sandy soils in the region, farmers have not been confident in tackling some of the other soil types in the region.

A feature of soils in the region is the presence of multiple soil types in one paddock, from rock to gravel to coloured and white sand. Each soil type has its challenges in applying the same soil amelioration practices as the deep sands, and return on investment following the deployment of soil amelioration practices. There is not a ‘one size fits all’ approach in paddocks where there are many soil types, and so farmers require the skills to identify the soil constraints in their paddock, understand which practice is likely to be effective in each soil type, and gain confidence to apply this knowledge and implement the practices across their farm.

WMG have been working in the area of soil amelioration for nearly 15 years, having first starting helping farmers address soil water repellency in the region after 2009. Partnering with DPIRD to deliver a range of trials that explored the first phase of soil amelioration which was new and exciting. The second phase of our research and demonstration activities was focused on reducing the environmental risks of soil amelioration through a later timing of practices (winter amelioration).

Our current focus in soil amelioration is on developing the next generation of strategies that build on the first generation of soil amelioration to improve long-term soil health. This is primarily in the field of stacking soil amendments and amelioration strategies, identifying soil amelioration options for paddocks with variable soil types, and in tackling the issue of re-emergence and/or prevention of re-emergence of soil water repellence in the region.

Over the next three years, WMG will establish a network of Participatory Action Research (PAR) groups and demonstration sites across the Geraldton and Kwinana West port zones. Each year, 1-2 sites will be established with local PAR groups that build on the learnings from previous year to develop the farmer knowledge base on successful soil amelioration strategies.

The PAR groups will explore the three key aspects of soil amelioration on variable soil types: how to diagnose paddock scale soil constraints, identify the most appropriate amelioration method(s) and highest ROI for the paddock, and gain confidence/experience in applying these practices through peer learning and knowledge sharing. Over the course of the project, each PAR group will visit demonstration sites and leading farmers who have made significant progress in understanding and addressing paddock-scale variability and how this affects the implementation of soil amelioration practices.

Project Objectives

The outcome of this project will be that by 2026, 30% of the growers in the Geraldton and Kwinana West Port Zone will have increased knowledge of management techniques to overcome non-wetting issues.  

Trial sites will be established in 2024 and will continue into 2025, with a partial economic analysis to be completed at the end of 2024, and a full economic analysis conducted at the conclusion of the project to evaluate the range of practices employed and their efficacy. 

Latest Updates

• 
  When soil “wakes up”: Ryegrass responses to amelioration
  At Gillingarra, a flush of ryegrass following deep soil mixing has offered an unexpected insight into how soil disturbance can “wake up” both biology and weeds. The findings are helping refine management approaches within the GRDC Soil Water Repellence Project.
• 
  Evolving insights from the Soil Water Repellence Project
  The second year of the Soil Water Repellence Project is revealing how soil amelioration effects shift over time. From Dandaragan to Moora, grower collaboration is helping uncover what works, what changes, and how management needs to evolve as soils respond.
• 
  Amelioration and Nutrition in Focus: WMG & Summit Crop Walk at Minty’s
  A big turnout at Minty’s saw growers tour Summit’s trials and get a mid-season look at WMG’s Soil Water Repellence Project trial. Early results showed improved establishment and reduced compaction, while 2024 economics highlighted the costs and returns of different machines.
• 
  Nitrate Nitrogen vs. Total Nitrogen: Making Sense of Plant Analysis
  Plant testing of a local wheat trial showed big differences in nitrate-N but similar total N across treatments. The results explain why both measures matter and how tillage can influence nitrogen uptake and conversion.
• 
  Soil Strength Following Amelioration: Year Two Results
  Second-year results from the Creagh site in Dandaragan show soil amelioration continues to improve root depth and structure, particularly with Nufab and Fanger treatments, despite some reconsolidation. Findings highlight lasting benefits for crop resilience on gravelly sands.
• 
  Year Two Trials Underway for Soil Water Repellence Project
  The Soil Water Repellence Project is now in its second year, with three trial sites comparing amelioration strategies on different soil types. Early establishment results are in, with monitoring to continue through 2026.
• 
  Dig First, Rip Later: Why Testing to Depth Matters Before Soil Amelioration
  If you are considering soil amelioration this year, testing to depth is essential. We unpack why knowing what lies beneath the surface can help avoid costly mistakes and improve outcomes from deep tillage.
• 
  Turning Dirt at WMG Pop-up Machinery Demo Days
  Our recent soil amelioration demo days at Dandaragan and Gillingarra showcased a range of implements in action. Read what was on display, what was learnt, and why matching machine to soil remains key.
• 
  Soil Amelioration & Groundcover Post-Harvest: Implications for Farmers
  Post-harvest groundcover matters—especially in fragile soils. Learn how soil amelioration improved biomass, reduced weed pressure, and protected soil in a 2024 Dandaragan trial, offering practical insights for managing erosion, moisture retention, and resilience between harvest and seeding.
• 
  Understanding Soil Water Repellence: Causes, Risks and Management Options
  Water repellence is a major constraint in sandy soils—but strategic amelioration can help. Learn what causes repellence, how it affects crop performance, and which management options can improve infiltration, reduce erosion, and support long-term soil function.
• 
  Evaluating the Economics of Soil Amelioration Strategies for Non-Wetting Soils
  How can different soil amelioration methods improve crop yields and farm profitability? See our economic analysis of the 2024 season results from the Dandaragan Soil Water Repellence trial site to find out more.
• 
  How can amelioration affect crop uptake of nutrients in gravel soils?
  Explore how soil amelioration methods like deep ripping and inversion tillage impact nutrient uptake in gravel soils with results and analysis from the Dandaragan Soil Water Repellence Project trial site.
• 
  Capturing the benefit of increased plant growth following amelioration
  How can we get the most out of increased plant biomass in the first year of soil amelioration? Read on to explore insights for grain-and-graze, hay production and other mixed farming systems.
• 
  How does ameliorating gravel soils affect weed populations?
  Explore how the results from the first year of the Soil Water Repellence Project have demonstrated that soil amelioration methods can have significant added benefits such as reducing weed populations.
• 
  Gravel Soil Amelioration Crop Walk – Farmer Summary
  Explore the insights, learnings and key discussion points from our Gravel Soil Amelioration Crop Walk at the Creagh’s Farm in Dandaragan, including synthesised notes, treatment images and a downloadable information sheet from the event.
• 
  Initial results from amelioration of gravel soils at Dandaragan trial site
  Discover some of the early results from the Dandaragan gravel soil amelioration site including insights on soil water repellence, soil testing data and plant establishment.
• 
  Soil amelioration & water repellence: Investigating the next generation of strategies
  Learn about one of our newest projects focusing on soil amelioration and developing the next generation of strategies to combat soil water repellence and improve long-term soil health, including a look at our first site’s progress and a short drone video of some amelioration in action!

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