It’s one of the most frustrating things about some sandy soils — the rain finally comes, and yet the moisture won’t penetrate.
Instead of soaking in, water sits on the surface, leaving crops struggling right from the start.

Water repellency is a widespread problem across sandy cropping regions, but the good news is we’re learning more about what causes it — and what you can do to manage it.

What Causes Soil Water Repellency?

As Professor David Henry explains in our latest MSF FarmTalk podcast, water repellency is driven by a build-up of waxy residues on soil particles. These coatings come from plant residues and change the soil surface chemistry, stopping water from moving into the soil profile the way it should.

Surface chemistry, soil texture, seasonal conditions, and past management practices all play a role in how bad repellency becomes, but repellency is mostly a problem that develops in sandy soils due to the relatively low surface area on sand particles

What can be done about it?

As far as solutions go, there are a few options, with many farmers using wetting agents in furrow to overcome non-wetting. If clay is available, either spreading clay or delving works too, and even though it’s a much more expensive approach, it’s also more long lasting.  No till helps too, since intact standing stubbles do provide pathways for water to enter the soils along intact root channels.

Want to Know More?

The “101 Questions About SA Cropping Soils You Were Never Game to Ask” book tackles water repellency head-on, covering the practical questions farmers are asking, like:

• Q50. Why do soils become water repellent?
• Q55. How do wetting agents work?
• Q52. How deep is the repellent soil layer?
• Q53. Why is crop establishment worse on water repellent sand when sown dry?
• Q60. Does fire create water repellent soil?

If you’re dealing with non-wetting paddocks or want to better understand how to manage these tricky soils, this resource is packed with clear, real-world answers.

Find all 12 questions and answers on water repellency in Chapter 7 at the Soils Connect website.

Want to dive even deeper?
Catch the full conversation with Professor David Henry and Nick Paltridge on the MSF FarmTalk podcast.

This podcast is supported by the South Australian Grain Industry Trust (SAGIT) as part of the project Enhancing farmer knowledge of soil function to improve management outcomes.

Thanks to Professor David Henry from the Centre for Sustainable Farming Systems at Murdoch University for joining us, and to GRDC for supporting ongoing research into practical solutions for managing soil water repellency (GRDC Code: UMU2501-005RTX).