Header image

Soil Water Repellency in Sandy Soils: Understanding the Contributions of Climate and Vegetation

Tracks
Wednesday, July 23, 2025
9:44 AM - 9:56 AM

Overview

David Henry | Murdoch University


Speaker

Agenda Item Image
Professor David Henry
Professor
Murdoch University

Soil Water Repellency in Sandy Soils: Understanding the Contributions of Climate and Vegetation

Abstract

Sandy soils are highly susceptible to developing Soil Water Repellency (SWR), which is a major constraint for agriculture. The severity of SWR has been shown to directly correlate with soil texture, percentage total organic carbon, soil moisture. However, SWR shows significant spatial and seasonal variation, even on a paddock scale. Our recent work shows the relative importance of different climate factors on the severity of SWR.

SWR arises from coatings of organic molecules on sand grains and formation of hydrophobic interstitial matter. The organic compounds that contribute to SWR enter soil by being released from living plants, the decomposition of plant material, and microorganism interactions. It is accepted that amphiphilic compounds (containing both a polar hydrophilic and a non-polar hydrophobic functional group) are the class of compounds predominantly responsible for water repellency in sandy soils. However, the amounts of the different compounds released is species specific. Experimental work has identified the efficacy of these different compounds at inducing water repellency, including loading levels and temperature effects. Native Australian species are highly effective at inducing SWR, but agricultural species can also contribute to the phenomenon. We have also found that different parts of the same plant can induce different levels of SWR.

Complementary computer simulations reveal how the compounds are arranged on soil particles for these different loading levels. Our investigations have also revealed the effects of pH on both the inorganic and organic components of soil and how these relate to observed changes in soil water repellency. The findings of these studies are guiding our understanding of how current SWR amelioration treatments function and will allow us to provide farmers with guidelines for managing SWR.

Biography

David is Professor of Chemistry at Murdoch University. His research is focussed on Materials Chemistry applied to agricultural and biomedical applications. He has many years of experience in soil analysis with a focus on characterising soil organic matter in relation to soil constraints such as Soil Water Repellency and Soil Health. His research group are developing efficient extraction and analysis methods to support agriculture. This work is complemented by materials modelling and materials development to address soil constraints for cropping in Western Australia.
loading