Claying by delving brings subsoil clays up to the surface. It’s a proven treatment for water repellency. Integrating clays into sandy topsoils also changes their nutrient status. What happens depends on the specific clay material involved.
Testing of clay material prior to spreading or delving is very important to ensure a beneficial outcome. Not all clays are the same, some have favourable characteristics while others can be very inhospitable Soil testing to assess pH, Potassium and a range of other properties including potential toxicities is a necessity. Clay content should be known to ensure the right amount of clay is incorporated. This is done through a Particle Size Analysis, or Particle Analysis test.
Perform claying operations in paddocks with the more favourable subsoils first to maximise the benefits.
If the paddock’s subsoil material is unfavourable consider not treating, or bringing other clays to the paddock over delving.
Spread, delve, spade, invert, a GRDC best practice guide to the addition of clay to sandy soils.
Richard Bell, Murdoch University WA, James Easton CSBP, Liam Ryan DAFWA.