Lawn amendment idea
 

While reading about organic lawn care, a blog mentioned the idea of digging a hole two or three feet down with a post hole digger and filling it in with compost. The idea being this would create a localized area for soil microbes and worms to grow and then spread to the rest of the yard over time. It made me think about terra preta and how it grows over time. Any thoughts on digging a hole and filling it with biochar and compost to encourage the same thing?

I'm no lawn care expert by far. However, it makes sense to me. A few nutrient rich areas will slowly spread to the surrounding areas.

I too think that it may be some helpful until this spread in a limit. You should better take the advice from professional gardener.

Most of the topsoil that forms naturally is only a few inches deep. The organic matter thst builds up over a couple of inches tall is quickly colonized and digested by things the Orkin man seeks to wipe out: termites, ants, etc. These insects do the job you are describing building their homes.

When you want to enrich a certain area, just pile up organic matter on the plot a few inches thick. Let it sit there for a few months and it will miraculously shrink. If you need or want deeper topsoil, plow or till the aged material in right before planting, then pile up some more organic matter on top. Dont worry, you wont kill all of the ants and worms.

your idea has been used in gardens for a long time. If the conditions were right i think it may work for you put why not just aerate the lawn and rake compost into the holes?