Project overview

With another dry start across much of the South Australian Mallee in 2025, growers were once again faced with difficult sowing decisions.

Low summer rainfall, limited stored soil moisture and a late seasonal break placed pressure on crop establishment across many parts of the region. As dry sowing becomes an increasingly common strategy in low rainfall environments, understanding where deeper sowing can improve establishment, and where it may increase risk, is becoming increasingly important.

To help investigate this, demonstration trials were established across three Mallee locations in 2025:
• Bowhill, SA.
• Waikerie, SA.
• Lameroo, SA.

The project built on findings from similar demonstrations conducted in 2024 across the NSW, Victorian and South Australian Mallee. Earlier work showed promising results from deeper sowing into moisture, particularly in barley crops and on lighter soil types.

The 2025 demonstrations aimed to test whether crop establishment could be advanced by sowing deeper into available moisture under tougher seasonal conditions.

Each site presented different soil types and seasonal challenges:
• Bowhill focused on non-wetting sandy soils.
• Waikerie experienced severe wind erosion and a lack of sufficient early rainfall.
• Lameroo introduced lentils into the trial program on sandy soils over clay.

Across the sites, researchers compared different sowing depths and crop varieties to better understand how crops respond under dry sowing conditions in the Mallee.

While 2025 proved to be a difficult season, the project delivered valuable insights into the opportunities and limitations of deeper sowing in low rainfall environments.

Key takeaways from 2025

• Deep sowing improved crop establishment and grain yield at Bowhill on non-wetting sands.
• Shallow sowing (20 mm) performed better at Waikerie and Lameroo under harsh dry conditions.
• Wind erosion had a major impact on crop establishment at Waikerie and Lameroo.
• Commodus CL barley consistently established better than Titan AX barley and Calibre wheat at Waikerie.
• Lentils struggled to establish under deep sowing conditions in the dry 2025 season.

2025 season conditions

Seasonal conditions across the Mallee were challenging.

Low summer rainfall, a late break to the season, and decile 2–3 growing season rainfall created difficult establishment conditions across all three sites. Sites also experienced significant wind erosion, causing furrow infill, sand blasting and plant losses.

These conditions provided a strong test of whether deeper sowing could improve crop establishment in difficult seasons.

Bowhill — Deep sowing showed potential on non-wetting sands

At Bowhill, deeper sowing (40-80 mm) increased yields by 74% compared to shallow sowing.

The site experienced low summer rainfall and decile 2 growing season rainfall, however, wind erosion pressure was lower than at Waikerie.

Plant establishment was monitored across three sowing depths — 20 mm, 40 mm and 80 mm — using Commodus CL barley, Titan AX barley and Calibre wheat.

Early establishment counts showed crops sown deeper established faster than the shallow-sown treatments. By the final establishment count, all treatments had reached similar plant numbers, however, the earlier emergence advantage remained important.

Researchers believe the non-wetting nature of the sandy soil played a key role. Rainfall may have funneled into the furrows and infiltrated deeper into the profile where seed had been placed.

Yield snapshot

What does this mean?

The Bowhill site demonstrated there may be value in deeper sowing on non-wetting sands, particularly where furrows help capture and direct rainfall into the seed zone.

Waikerie — Dry conditions favoured shallower sowing

The Waikerie site experienced a very dry start to the season, with less than 10 mm of rainfall recorded across April and May.

The site also suffered significant wind erosion throughout the growing season.

Unlike at Bowhill, shallow sowing (20 mm) performed better at Waikerie.

Plant establishment assessments showed crops sown at 20 mm consistently achieved higher plant numbers than the deeper sowing treatments.

Even the best treatments only achieved around 50 plants/m² — well below the target population of 130 plants/m².

Yield snapshot

What does this mean?

Under harsh dry conditions and high wind erosion pressure, deeper sowing increased establishment risk at Waikerie.

Lameroo — Lentils struggled under deep sowing

Lentils were included in the 2025 demonstration for the first time.

Seasonal conditions at Lameroo were difficult, with low early season rainfall and ongoing wind erosion affecting crop establishment and survival.

Plant numbers declined as sowing depth increased.

The shallow 20 mm treatment achieved the strongest establishment, while the 80 mm treatment performed poorly.

The trial was ultimately not harvested due to poor plant numbers.

What does this mean?

In seasons with very limited early moisture and ongoing erosion pressure, deeper sowing increased establishment challenges for lentils at Lameroo.

Final thoughts

The 2025 season reinforced that there is no one-size-fits-all approach to dry sowing in the Mallee.

Deep sowing (40-80 mm) showed promising benefits at Bowhill on non-wetting sands, with improved establishment and grain yield. However, under the harsher seasonal and erosion conditions experienced at Waikerie and Lameroo, shallow sowing (20 mm) generally performed better.

The project highlights the importance of considering soil type, stored soil moisture, seasonal outlook, erosion risk and crop type when making sowing depth decisions in low rainfall environments.

Read the fact sheet HERE

More information can be found via the MSF Derisking the Seeding Program Project Page

This work was supported by the Australian Government’s Future Drought Fund