Not a direct answer to your question but the first step in replacing a lawn with a garden the nodig way is to cover the grass with something like cardboard and then cover the cardboard with as much as 12 inches of woodchips.
You can get the woodchips for free most of the time as arborists need places to dump. Try to be careful of the type of tree however as some trees have a higher activity than others.
Not a direct answer to your question but the first step in replacing a lawn with a garden the nodig way is to cover the grass with something like cardboard and then cover the cardboard with as much as 12 inches of woodchips.
You can get the woodchips for free most of the time as arborists need places to dump. Try to be careful of the type of tree however as some trees have a higher activity than others.