To assess the impact of the rate of application of clay-rich subsoil to water repellent sand on grain yield and the interaction with incorporation method.

• This trial clearly demonstrates the importance of matching clay application rate and incorporation method when clay spreading for water repellence. For subsoils with a clay content of about 30% using a rate of 100-150 t subsoil/ha incorporated with offsets to a depth of 120-150 mm was sufficient to overcome the repellence and given wheat yield increases of 11-18%.
• Alternatively subsoil application rates of 250-350 t/ha are probably required if the clay is to be incorporated to 250-300 mm with a rotary spader and this gave similar yield increases of 11-14% on what is a better soil type with higher inherent yield potential.
• The main benefit of higher clay application rates and deeper incorporation seemed to be in the canola year, although more seasons with canola need to be assessed to confirm the validity of this finding.