Date
2026/02/13
Organisations
Department of Primary Industries and Regional Development
Understand the likely impact of clay spreading and mixing ahead of your significant investment in the soil
Before spending the time and money spreading clay, it is important to know how much you need based on the clay source you have available.
This simple three-in-one calculator allows you to vary rates, clay % and mixing depth to:
- Calculate the resulting clay % in your soil after application of a clay subsoil
- Estimate the required clay application rate to achieve a target clay %
- Use on-farm data to more accurately calculate final clay % and soil nutrient concentration.
Note: This calculation assumes 100 percent efficiency of clay mixing throughout the profile which is often not achieved in the paddock with current technology. The calculator provides an approximation of final clay percentage within an evenly mixed (homogeneous) profile.
This calculator represents an initial prototype. Ongoing development will improve its ability to predict soil clay percentage through varying depths of mixing.
This work was completed as part of the Soil Water and Nutrition (SWAN) strategic collaboration, a joint investment of the Grains Research and Development Corporation (GRDC) and the Department of Primary Industries and Regional Development (DPIRD).
Clay spreading calculations for soil amelioration
