Output 1

By May 2029, a comprehensive understanding of the relative contribution of crops and cropping sequences to the expression and severity of soil water repellency (SWR) will be available for different environments and soil types. This information will be provided in a format easily accessible to growers and advisors.

This output will develop evidence on how major common crop types (wheat, canola, barley, oats, and pulses) as well as pasture species (ryegrass and clover), contribute to the expression and severity of SWR both within and across crop rotations. Specifically, it will account for the influence of both short-term seasonal factors, particularly rainfall deciles, and long-term changes driven by different crop sequences on the persistence and intensity of SWR. Throughout the research phase, the form and delivery of the new information will be co-designed in consultation with GRDC managers, growers, and industry members. The aim is to ensure that the information is not only scientifically robust but also practical and freely accessible to all stakeholders.

Multiple layers of information (including proximal and remote sensing data) may inform the likelihood of SWR expression and severity at sub-paddock level as influenced by agronomic management and seasonal conditions. Information and resources that are generated, developed and delivered must help growers manage SWR both strategically (with recommendations on crop sequence, or strategic soil tillage such as spading), and tactically (including optimal sowing times, direction of sowing and the use of soil wetters) and consider seasonal and in-paddock variability of SWR. Note – these will be validated in Output 2.

The successful applicant will need to collaborate with GRDC research partners. These include CSIRO and DPIRD researchers (CSP2403-017RTX and DAW2204-003RTX) to facilitate access to GRDC current farming systems investments, and University of Sydney (UOS2206-009RTX) to build and leverage current approaches or technology from other approaches to identify soil constraints that could be adapted for seasonal prediction of SWR

Output 2

By December 2028, cost-benefit analysis of SWR management strategies

This output focuses on evaluating the cost-benefit of various management strategies to manage soil water repellency (SWR).

A minimum of 6 on-farm case studies per year over three years must showcase management strategies underpinned by evidence from both existing and emerging (developed in Output 1) information and resources on incidence and severity of SWR, and represent diverse regions, environments, and soil types in Australia. Case studies provide the platform to:

a)  validate the relative contribution of identified factors to the incidence and severity of SWR.

b)  discuss and evaluate both short- and longer-term management approaches.

The output will provide information for decision-support tools for growers, promoting more cost-effective and efficient SWR management.

Output 3

By April 2026, complete an analysis of biologicals and wetter chemistry available for growers, opportunities for improvement and a business case for conducting future wetter chemistry work

Annual application of soil wetter products only treats the symptoms of SWR and does not address the underlying causes. Current soil wetter products include surfactants that may even aggravate the issue, if their chemistry is similar to the hydrophobic compounds that are responsible of SWR. The first step to a possible solution to this issue will be to conduct an analysis of the current available wetter chemistry available for growers, opportunities for improvement and a business case for conducting future wetter development. This output will also consider if any biological approaches such as soil microbes could alleviate SWR and what mechanisms make it possible.

This output will deliver a report to GRDC about the analysis of current wetter chemistry, opportunities for improvement and a business case for conducting future wetter chemistry development. The report will also contain recommendations on the optimum rate and placement of wetters and possible areas of chemistry improvement.