If you were going to commission a moonshot investment – an exploratory, groundbreaking project with the scale of benefits uncertain – to boost Australian grain production, redesigning the earth certainly fits the bill

Known for their geological age, often poor fertility and a variety of constraints, Australian soils present unique challenges that make a so-called moonshot approach to long-term soil amelioration potentially revolutionary.

Such an ambition is being driven by Dr Gaus Azam from the WA Department of Primary Industries and Regional Development (DPIRD). With GRDC investment, this moonshot initiative seeks to redesign soil profiles to improve soil water-holding capacity and unlock higher yield potential.

Moonshot innovation, a term derived from the Apollo 8 spaceflight project, is characterised by its blue-sky approach, transformative leadership, teamwork and culture – and it is embodied by Dr Azam, whose determination and charisma have rallied a team of skilled researchers.

The team includes Glenn McDonald, Wayne Parker, Kanch Wickramarachchi, Bindi Isbister, Chad Reynolds, Dr Stephen Davies, David Hall, Dr Md Shahinur Rahman, Dr Hasin Rahman, Tom Edwards, Alice Butler and many others from the department’s soils team and other research areas in DPIRD. It combines years of soil amelioration experience from various regions of WA.

Dr Azam says the project focuses on radically re-engineering the physical and chemical properties of the soil profile to provide crops with an unconstrained soil environment.

A key part of this effort involves using road construction equipment to loosen and reconstitute soil layers while adding nutrients and other soil ameliorants such as lime, gypsum and organic matter to soil layers  where needed.

“We were shooting for the stars in terms of pushing yield potential and expecting to achieve 95 per cent of the rainfall-limited yield potential,” Dr Azam says.

The moonshot approach

The process involves diagnosing soil constraints, consulting experts in soil, crop and climate sciences, and conducting experiments in the lab, glasshouse and field. The project also included a financial analysis to evaluate the benefits of these interventions. It targets multiple soil types, from deep sand to heavy clays, developing protocols to spatially diagnose constraints across entire paddocks and at different depths.

Over five years (2018–23), 12 soil profile re-engineering experiments were conducted across WA’s grain growing regions, including low, medium and high-rainfall zones (Figure 1). These trials tested a range of re-engineering treatments, comparing them with surface-based amelioration methods.

“The result is a tailored approach to soil re-engineering in each region, which offers long-lasting, profitable solutions.”

Soil water management

Kanch Wickramarachchi, who led the glasshouse and laboratory studies using cores from paddocks, found that while physical tillage enhanced soil properties, it also increased evaporation.

“This would be problematic in the field, particularly in dry seasons, as experienced  in 2023,” Dr Azam says.

Figure 1: Distribution of soil profile re-engineering experiments across the grainbelt of WA.

Source: DPIRD

Tailored approaches

Tailored approaches were applied in regions with different soil types.

In sandy soils with low clay content, surface applications of nitrogen were found to be as effective as deep banding once the soil profile has been re-engineered.

The project also highlighted the importance of gypsum and the right clay rate to maintain water infiltration, water retention and soil structure. For heavier, calcareous, sodic and alkaline soils, organic matter was found to improve soil structure and nutrient availability.

Field studies also confirmed that soil  profile re-engineering to depths of up to  80 centimetres improved root development, extending crops’ growth periods by up to three weeks and boosting yields and water  use efficiency (WUE).

Yield improvements

In deep sands and sandy duplex (texture contrast) soils, re-engineering led to remarkable yield increases, with improvements ranging from 1.8 to 4.3 times, depending on soil type, crop and seasonal conditions. These results were especially significant in duplex soils, where crops like canola, wheat and barley benefited greatly from removal of the soil constraints.

“The long-term benefits of re-engineering were also evident in sandy soils, where mixing treatments proved effective in treating water-repellent soils. This led to net profits ranging from $90 to $317 per hectare per year,” Dr Azam says.

Inspired by innovative soil amelioration work hosted on his Holt Rock property, Cameron Mudge has used a Reefinator on some of his land to break up rocky outcrops and improve productivity of paddocks. Photo: Evan Collis

Mixed results in heavy soils

The effects of soil profile re-engineering in heavy soils have been mixed.

“In some areas with heavier soils, such as on Cameron Mudge’s property at Holt Rock, re-engineering nearly doubled yield, but in others, like the site at Stewart Witham’s in Toolbrunup, the results were more modest,” Dr Azam says.

These mixed results highlight the importance of site-specific strategies and the need for continued monitoring to understand the full benefits of heavy soil re-engineering.

While tillage practices on heavy soils have improved soil properties, their effects on yield have been inconsistent across sites and seasons. In low-rainfall areas, especially on heavy soils, biological and physical tillage showed limited effectiveness in improving WUE and productivity. However, tillage increased evaporation while sorghum (SSS – Super Sweet Sudan) increased transpiration, both impacting soil moisture levels.

“This points to future research that should focus on alternative techniques such as mineral mulches and water harvesting, which may offer more reliable benefits in challenging environments,” Dr Azam says.

At the grower level, addressing soil issues like acidity, compaction and water repellence has generally improved yields and soil properties. However, Dr Azam emphasises that it is necessary to fully understand the range of soil constraints present throughout the soil profile and have a plan to address them to achieve the potential benefits.

Mission number two: The SWAN collaboration

Building on the positive outcomes from DPIRD and GRDC’s last decade of investment in soil and crop nutrition research, development and extension, which included the new yield potential demonstrated by the soil re-engineering project, a second major initiative has been launched: the Soil Water and Nutrition (SWAN) collaboration. This $55.9 million strategic partnership between GRDC and DPIRD aims to improve water and nutrient use efficiency in WA grain production by over 10 per cent. The five-year project will focus on expanding soil re-engineering, nutrient management and fostering industry adoption of these strategies.

More information: Dr Gaus Azam,  gaus.azam@dpird.wa.gov.au

Useful resources: GroundCover^TM story – Researcher on a machinery mission to re-engineer soils