Year Two Trials Underway for Soil Water Repellence Project

Aug 15,2025 Project Update Article, Soil Amelioration Project, 2025, Projects, RAD2406,

By Simon Kruger & Kate Parker, WMG

The GRDC funded Soil Water Repellence Project has entered its second year, with three demonstration trial sites now established across the West Midlands region. Two new sites have been added for the 2025 season alongside the original 2024 site, allowing for a broader look at how different soil types respond to amelioration treatments.

Water repellence is becoming a challenge on a wider range of soil types in the region, extending beyond the deep sands traditionally targeted for amelioration. The project is taking a Participatory Action Research approach, working with local growers, researchers, consultants and industry representatives to test and compare management strategies. The aim is to build grower confidence in addressing non-wetting soils and to evaluate the return on investment of different treatments.

Trial Sites and Treatments

Site 1 – Dandaragan: Shallow sand over gravel, lupins sown in May. Treatments include Plozza plough, Fanger plough, and Nufab rip/delve options.
Site 2 – Gillingarra: Sand over gravel and true gravel plots, barley sown in June. Treatments include Horsch Tiger, Plozza plough, and Fanger plough (Figure 1).
Site 3 – Rowes Rd: Deep grey-yellow sand, wheat sown in May. Treatments include single and stacked machinery passes using ploughs, delvers, spaders and rippers.

All trials follow host farmer fertiliser and crop protection programs, with establishment, biomass, and yield to be monitored through 2026.

**Figure 1.** Site 2 treatments immediately post implementation.

Early Findings

Soil testing at Site 1 confirmed that last year’s amelioration continues to reduce surface water repellence, and increase root penetration depth. At Site 2, water repellence was evident, with field observations pre-sowing showing weeds primarily growing in the previous years furrows, and indication of water infiltration limitations. Site 3’s deep sands displayed significant water repellence before treatment, and the early results suggest marked improvements in rooting depth.

Plant establishment results have varied:

Site 1: Nufab double pass, Plozza plough, and Nufab single pass showed higher lupin establishment compared to untreated controls.
Site 2: No significant differences yet in barley establishment, with variability linked to ryegrass pressure, seeding depth issues and rocky ground.
Site 3: All ameliorated treatments improved wheat establishment over the control, with denser and more uniform crops in treated plots.

**Figure 2.** Plant establishment for each treatment at site 1 taken 09/06/2025.

**Figure 3.** Plant establishment for each treatment at site 2 – sand over gravel plots, taken 16/07/2025.

**Figure 4.** Plant establishment for each treatment at site 2 – true gravel plots, taken 16/07/2025.

**Figure 5.** Plant establishment for each treatment at site 3 taken 02/07/2025. PDH is a combination of Plozza plough, Delver and Horsch Tiger; PDS is combination of Plozza plough, Delver and Spader.

**Figure 6.** Image of Site 3 treatments PDS (left) and Control (right) taken 02/07/2025.

Seasonal Conditions

A late break to the season delayed crop emergence, but July brought above-average rainfall across all sites. While the wet conditions may have eased some establishment challenges, they also make it harder to distinguish treatment effects at this early stage. These results underline the importance of long-term monitoring to understand how amelioration interacts with seasonal variability.

Next Steps

Monitoring will continue through the season, with biomass cuts, plant tissue testing and yield mapping planned. A full economic analysis will be carried out at the end of the project to determine the long-term value of each treatment.

This project is supported by the Grains Research and Development Corporation (GRDC).