The best replacement for clay soil is sandy soil.

The best alternatives to clay soil are rated as following:
★★★★★  sandy soil
  sand
  sand soil

Your alternative for clay soil is not listed? Suggest!
Speaking about clay soil, one probably shouldn't forget about gypsum.

Other search terms related to clay soil and their ratings are:
★★★★★ gypsum
★★★ peat moss
You have in mind a companion for clay soil and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of clay soil in all years. Click on graph for more.
clay soil
sandy soil
sand