Development of soil water repellency management options for Australian grain growers.

Soil water repellency (SWR) is a condition that makes soils temporarily resist wetting, restricting water availability for crops. SWR is associated with the presence of organic material in the soil, with incidence and severity influenced by plant type and species, crop rotation, stubble load and breakdown. SWR affects more than 5M hectares in Western and Southern Australia and costs growers an estimated $100 million per annum through reduced yield due to reduced crop germination, nutrient storage and availability, and plant-available water.

Currently growers use expensive and challenging techniques to manage SWR, such as strategic tillage, spading ($150/ha on average conducted every 3-5 years), clay application ($800/ha on average conducted once) on or near row seeding or annual applications of wetters (up to $22/ha applied annually). Given the unpredictable and transient nature of SWR alongside a lack of understanding where and when to target soil amelioration, wetters are applied as an insurance option, despite current wetter chemistry being inadequate to overcome SWR and under certain instances could be exacerbating the issue.