Comment by mapt

A lot of these observations about the miraculous soil caretaking of the elder Native Americans are in all likelihood just "Look at this garbage dump, so fertile, such agricultural skill!"

Broken half-fired terra cotta is effectively unusable rock. Terra cotta is semi-disposable, so lots of potsherds are produced per person-year before plastics/glasses/metals are introduced. It's the single most common and best-preserved archeological artifact. Broken pottery was used in place of sand to stabilize the clay in new pottery, but other than that it doesn't have many special qualities.