Building Soil Function

Lowbank Soil Amelioration Trials

On-Farm Soil Amelioration Trials in Lowbank – Improving Marginal Soils for Sustainable Cropping

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  • Deep Ripping + Organic Amendments Improve Sandy Soils

    Active Inclusion Deep Ripping (AIDR) combined with chicken manure increased root depth, improved crop growth, and enhanced fertility on sandy soils—even under extreme drought conditions.

  • VRT and Soil Testing Help Optimise Inputs

    Variable Rate Technology (VRT) trials showed that lower fertiliser rates could yield similar results to higher rates during dry seasons, particularly when guided by NDVI imagery and targeted soil testing.

  • Wetting Agents Show Promise – But Are Inconsistent

    Applying wetting agents improved lupin crop performance in some of the most non-wetting sands. However, responses were inconsistent across paddocks and seasons, highlighting the need for site-specific decisions.

Project Overview

Restoring Soil Function for Sustainable Farming in Lowbank

This Lowbank-based soil project explored practical, farm-scale approaches to rehabilitating poorly performing soils such as non-wetting sands, sodic saline clays, and degraded sandhills.

The project aimed to help farmers identify safe, cost-effective strategies to boost productivity and reduce seasonal risk. Led by the Lowbank Agricultural Bureau and supported by UniSA, five field sites were used to test combinations of mechanical and organic treatments, including AIDR, manure, wetting agents, and VRT.

The project also featured a strong extension component, including field days, crop walks, and a harvest report, allowing a broader group of growers to see results and share insights.

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What We Learned

Key Discoveries and Outcomes from Lowbank

  • Farmers Helped Shape the Focus

    Local Ag Bureau members identified the most pressing soil issues, ensuring the project addressed real, on-the-ground challenges.

  • Deep Ripping with a Twist Works Better

    Active Inclusion Deep Ripping (AIDR) improved root growth and crop health more than traditional ripping—especially when paired with manure.

  • Manure Makes a Big Difference on Sandy Soils

    Adding chicken manure helped fix blown sandhills, improving fertility, water retention, and long-term productivity.

  • Wetting Agents Can Help—but They’re Not One-Size-Fits-All

    Wetting agents boosted lupin growth in some areas, but results varied depending on crop type and soil conditions.

  • Precision Fertiliser Pays Off in Dry Years

    VRT trials showed that lower fertiliser rates often gave the best returns during dry seasons, proving the value of zone-based decisions.

  • Seeing Is Believing: Field Walks Sparked Interest

    Crop walks and field days let farmers see root growth, compare treatments, and ask questions directly in the paddock.

  • Drone Images Brought the Data to Life

    At harvest, aerial photos and charts made it easy to compare results—driving strong discussion and shared learning across the group.

  • On-Farm Trials and Treatments Tested

    – Tested AIDR vs conventional ripping across sodic clays, non-wetting sands, and degraded sandhills

    – Applied chicken manure and wetting agents to improve soil fertility, moisture retention, and crop establishment

    – Established VRT zones and fertiliser strip trials using NDVI mapping and targeted soil testing

    – Engaged farmers through crop walks and field days, supported by drone imagery and harvest data analysis

  • Soil Type-Specific Performance

    – On sodic saline clay: AIDR improved root depth by 15–20cm but deep seeding caused crop failure, showing how sensitive these soils are to machinery interaction.

    – On blown sandhills: Reshaping and AIDR led to barley yields of 2 t/ha with just 62 mm of rain.

    – On non-wetting sands: Chicken manure and AIDR enabled deeper root growth and better crop resilience than either treatment alone.

  • Risks and Limitations

    – AIDR treatments increased erosion risk on light sands—highlighting the need for good seasonal timing and rapid ground cover.

    – Wetting agent results were visually striking but not always aligned with yield or consistent across species.

    – Livestock interference (grazing on a demo site) made one sandy site unusable for harvest data.

    – Machinery-induced variability (e.g., uneven sowing depth) limited data in some trials.

Conclusion

Outcomes

  • AIDR significantly improved root penetration and crop growth, even in decile 1 rainfall conditions
  • Amending sands with manure produced better outcomes than ripping alone
  • Wetting agents showed some benefit in lupins but inconsistent responses across the paddock
  • VRT trials revealed that lower fertiliser rates delivered better margins in dry years, with responses varying by soil zone
  • Erosion risks associated with AIDR need to be managed, particularly in sandhills
  • The project has built confidence among growers, shifting initial scepticism into active engagement

What This Means
These trials confirmed that large-scale soil amelioration can work in challenging conditions, but success depends on site-specific treatment and timing. The work also highlights the importance of continued monitoring and refinement of methods, especially to address erosion and cost barriers.

The project has laid a strong foundation for further extension and adoption of best-practice soil management in Lowbank and surrounding areas.

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