Sand is sharper, so the rolling incurred on impact would graze your knees as a human (but not a T) but works much better as a shock absorber than garden soil does. Scraped knees or broken knees... But we're headed off-topic here...
I think Texas Blonde has the answer perfect. Sand and clay or sand and peat is your best bet - a mix over 100% sand.
I think Texas Blonde has the answer perfect. Sand and clay or sand and peat is your best bet - a mix over 100% sand.