Delivering agronomic strategies for managing water repellence in Western Australia

Enhancing productive capacity and management solutions to better manage soil water repellence will help reduce the opportunity cost from lost production associated with water repellence estimated at up to $330 million each year.

ACHIEVEMENTS

Banded wetting agents can make dry furrow sowing of water repellent soils more reliable.
Furrow sowing forms micro-relief, small ridges and furrows, into which water can be harvested.
One-off soil inversion results in the complete burial of the water repellent topsoil in a layer typically at a depth of 15-35 cm, and brings to the surface a layer of wettable subsoil.
Water repellence develops when there is an accumulation of hydrophobic organic substances in a susceptible soil. Hydrophobic compounds are derived from plant and microbial sources. Sands are more susceptible to developing repellence.

OVERVIEW

Water repellence is a widespread problem (link to more information) mostly affecting soils with low clay content or high organic matter levels in the topsoil, in the medium to high rainfall zones. The expression of water repellence appears to be increasing due to an increase in cropping frequency, drier and earlier sowing, minimum tillage and reduced break of season rainfall.

Soil water repellence results in uneven wetting of the soil profile and in poor, delayed and staggered emergence of crops, pastures and weeds and reduced productivity. Management options include improved furrow sowing methods, soil wetting agents, one-off deep cultivation and clay spreading or clay delving.

Partnering researchers from DAFWA, CSIRO and Murdoch University are working together to identify mechanisms and develop strategies to increase infiltration and subsequent use of rainfall to improve plant establishment and increase plant yields. Collaboration with key grower groups including SEPWA, Southern Dirt, Mingenew-Irwin, West Midlands as well as the University of South Australia and the University of Western Australia.

FUNDING

Project funded by the GRDC, in collaboration with the Department of Primary Industries and Regional Development (DPIRD) Agriculture and Food Division - formerly DAFWA