"Sunflower" wrote in message . ..
Mulch. You are not going to get a huge buildup as it breaks down over time.
Every 5-7 years, you can remove the top layer, but you are not going to get
a huge buildup by adding mulch annually.

Why do you suppose archeological finds are usually under 10-15 feet of
soil? They don't sink, they get covered up with mulched plant
material.