Agronomic Strategies to Optimise Productivity on Sandy Soils after Amelioration in South-East South Australia
Tracks
| Thursday, July 24, 2025 |
| 9:12 AM - 9:24 AM |
Overview
Speaker
Dr Melissa Fraser
Company Director
Soil Function Consulting
Agronomic Strategies to Optimise Productivity on Sandy Soils after Amelioration in South-East South Australia
Abstract
The Managing Sands Post-Amelioration project investigated strategies to optimise crop establishment and yield on recently ameliorated sandy soils in the Upper South East of South Australia. This research aimed to address key challenges associated with soil amelioration, including water repellence, soil compaction, nutrient redistribution, and wind erosion risks. Field trials conducted at Coomandook (2022–2024) assessed deep tillage techniques, seeding strategies, and targeted nutrient management approaches to enhance agronomic performance.
Results demonstrated that deep tillage, particularly inversion ploughing and chisel ploughing, effectively mitigated soil constraints by improving root zone accessibility to moisture and nutrients. Inversion ploughing significantly increased pH in acidic subsurface layers and enhanced water infiltration, leading to yield increases exceeding economic targets. However, nutrient dilution following soil disturbance highlighted the necessity for tailored fertiliser strategies to sustain productivity.
Optimised seeding methods were crucial in minimising wind erosion risks and ensuring successful crop establishment. Trials showed that combining in-row seeding with broadcast seed application improved early ground cover and plant density. In the second year, canola establishment in ameliorated plots was nearly double that of untreated controls, confirming the long-term benefits of amelioration.
Economic analyses revealed that while deep tillage incurred high initial costs, these were offset by substantial yield gains and increased profitability. Inversion ploughing, combined with strategic nitrogen application, achieved the highest partial gross margins over two years.
This project underscores the importance of integrating amelioration with precision agronomy to maximise returns on sandy soils. By aligning soil amelioration with targeted nutrient management and seeding practices, growers can enhance productivity, reduce risk, and improve the resilience of farming systems in sandy environments. Ongoing monitoring will be essential to evaluate the sustainability of these approaches over time.
Results demonstrated that deep tillage, particularly inversion ploughing and chisel ploughing, effectively mitigated soil constraints by improving root zone accessibility to moisture and nutrients. Inversion ploughing significantly increased pH in acidic subsurface layers and enhanced water infiltration, leading to yield increases exceeding economic targets. However, nutrient dilution following soil disturbance highlighted the necessity for tailored fertiliser strategies to sustain productivity.
Optimised seeding methods were crucial in minimising wind erosion risks and ensuring successful crop establishment. Trials showed that combining in-row seeding with broadcast seed application improved early ground cover and plant density. In the second year, canola establishment in ameliorated plots was nearly double that of untreated controls, confirming the long-term benefits of amelioration.
Economic analyses revealed that while deep tillage incurred high initial costs, these were offset by substantial yield gains and increased profitability. Inversion ploughing, combined with strategic nitrogen application, achieved the highest partial gross margins over two years.
This project underscores the importance of integrating amelioration with precision agronomy to maximise returns on sandy soils. By aligning soil amelioration with targeted nutrient management and seeding practices, growers can enhance productivity, reduce risk, and improve the resilience of farming systems in sandy environments. Ongoing monitoring will be essential to evaluate the sustainability of these approaches over time.
Biography
Dr Melissa Fraser is the Director and Principal Consultant at Soil Function Consulting, with over 20 years’ experience in agricultural research and extension across South Australia, Queensland, and the Northern Territory. Melissa specialises in overcoming constraints on sandy soils to enhance productivity in low and medium rainfall zones. She collaborates with CSIRO and PIRSA on research trials in SA and Vic and is a leading educator in soil management. Passionate about extension, she plays a key role in supporting growers through GRDC projects and industry events across the Southern Region.
