In WA an estimated 5 million hectares are affected or have the potential to be affected by water repellence. Sandy soils with less than 5% clay are most at risk of water repellence.
What Causes Water Repellence?
1. Water repellence is caused by a fungi/plant-derived dry coating of hydrophobic substance on soil particles or aggregates;
2. Some legumes such as lupins produce water repelling substances more than cereal crops; and
3. Microbial activity breaks down dead plant material in a way that contributes to the development of water repellence in susceptible soils.
Solutions and Preventions
• Adding clay to sandy soils can reduce water repellency but can be expensive;
• Rotate pasture paddocks with cereal crops to reduce build-up of plant waxes; and
• Maintain or improve soil structure by reducing or treating soil compaction and erosion.
Research continues for viable biological solutions to water repellence on broadacre farms using similar principles to biological clean-up of hydrocarbon spills.
CSIRO. 2015. ‘Water repellent soils.’ https://www.csiro.au/en/Research/AF/Areas/Sustainable-farming/Soil-water-landscape/Water-repellent-soils
Department of Primary Industries and Regional Development (DPIRD). 2018. ‘Utilising soil biological processes to better manage water repellent soils.’ https://www.agric.wa.gov.au/water-repellence/utilising-soil-biological-processes-better-manage-water-repellent-soils
DPIRD. Accessed 26/04/2018. ‘Water repellence.’ https://www.agric.wa.gov.au/climate-land-water/soils/managing-soils/water-repellence
Grain Research and Development Corporation (GRDC). 2018. ‘Managing water repellent soils in WA.’ https://grdc.com.au/archive/key-issues/managing-water-repellent-soils-in-wa
Unkovich, M. et al. 2015. ‘Management of water repellent sands in the Southern cropping region.’ CSIRO. https://publications.csiro.au/rpr/download?pid=csiro:EP161239&dsid=DS1