Optimising grain and pasture yields after amelioration

2025 – 2028

Dr Melissa Fraser

Meat and Livestock Australia, Grains Research Development Corporation, Murraylands Riverland Landscape Board  

CTLAP, Soil Function Consulting, host producers 

Sandy soils, nutrient management, amelioration, fertiliser efficiency

Upper South East (Meningie to Coonalpyn), Coorong District Council

Deep sandy soils dominate much of the Upper South East of South Australia and are often limited by low organic matter, nutrient constraints, water repellence, compaction and acidity. While amelioration practices are increasingly used to overcome these constraints, many producers remain uncertain about how fertiliser strategies influence the magnitude and longevity of yield responses.

This Producer Demonstration Site project brings together a core group of producers between Meningie and Coonalpyn to test how strategic soil testing and targeted nutrient applications affect crop and pasture productivity following amelioration. Demonstration sites will compare farmer standard practice with zone-based nutrient programs designed to correct phosphorus, potassium and sulphur deficiencies and achieve water-limited yield potential.

The project combines on-farm demonstrations, skills-based workshops and economic analysis to build producer confidence in precision soil sampling, nutrient planning and fertiliser timing. Early results show that nutrient limitations often persist after amelioration and that targeted fertiliser investment can improve biomass, grain yield and long-term soil fertility.

By tracking soil fertility, production and profitability over multiple seasons, the project aims to demonstrate practical, affordable nutrient strategies that help growers capture the full benefits of amelioration and make more informed input decisions.

Workshops and Field Walks

Three workshops and a regional field walk have been delivered to build grower capability in nutrient management on ameliorated sandy soils.

The first workshop, held in April 2025 at Meningie, focused on soil testing, nutrient balance and fertiliser decision-making for sandy soils. Producers developed a stronger understanding of maintenance versus capital nutrient investment, improved soil sampling methodology and gained practical tools to evaluate limiting factors and cost–benefit outcomes. A core producer co-design session followed, shaping demonstration priorities including fertiliser timing, nutrient imbalances, mapping and economic analysis.

In September 2025, a combined workshop and field walk at Coonalpyn explored precision approaches to nutrient management. Soil pits, spatial mapping layers and NDVI imagery were used to link crop performance with underlying constraints such as subsoil acidity and water repellence. Participants reviewed amelioration techniques including clay incorporation and deep tillage and discussed how zone-based soil sampling and variable-rate inputs can improve productivity and fertiliser efficiency.

The October 2025 Feed to Figures workshop strengthened participants’ ability to evaluate soil and grazing investments using discounted cash flow modelling. Working through real case study data helped producers connect agronomic decisions with financial outcomes, improving confidence in staging fertiliser inputs, assessing return on investment and managing risk.

Across these activities, participants reported strong knowledge gains and clear intent to adopt zone-based soil sampling, refine fertiliser strategies and apply economic analysis to input decisions. The workshops and field walk collectively support the project’s aim of helping growers capture the productivity benefits of amelioration through more targeted, data-driven nutrient management.

Year 1 Demonsatration Site – Meningie 

A Producer Demonstration Site was established near Meningie to evaluate fertiliser strategies aimed at closing yield gaps on ameliorated sandy soils. Soil testing prior to the trial identified phosphorus, potassium and sulphur levels below target, despite acidity constraints having been addressed through liming. The demonstration compares farmer standard fertiliser practice with a higher nutrient (full-rate) application and a split application approach designed to improve nutrient use efficiency over time. 

In the first season, a barley crop was monitored using NDVI imagery, peak biomass measurement and grain yield. Clear production differences were observed between treatments, with the full fertiliser strategy delivering the highest biomass and grain yield. These results confirm that nutrient limitations can persist following amelioration and that targeted fertiliser investment can rapidly improve productivity. 

Ongoing monitoring will include soil sampling, continued biomass and yield assessment, and evaluation of split fertiliser performance and economic outcomes. The demonstration is designed to provide practical guidance on fertiliser timing, nutrient investment and paddock zoning to help growers capture the productivity benefits of amelioration while improving fertiliser efficiency and profitability.