>>2728387Any organic material will help lossen clay soils. Biochar is great for water retention and microbe habit, but any compost, manure, wood chip/mulch, ect, will make the top soil much easier to work and your plants happier.
To use sand to loosen clay you have to hit over 50% sand. Not only is it potentially ungodly expensive but sand offers very little in nutrients, water retention, and the sand will eventually migrate/wash out and your sticky clay will return.
It's better to aim for 15-25% organics in your soil of any kind.
