• Alternatively, plots close to the homestead could be relatively fertile compared to distant plots because homestead plots may benefit from the addition of household refuse and other soil fertility enhancing materials (e.g., ash).

• They have names for many different kinds of plants, ways to diagnose and treat human and animal diseases, and methods to crop fertile and infertile soils.

• Forest and grassland ecosystems can create or regenerate fertile soils, degrade plant litter and animal wastes, and purify water, and this regenerative process is essential for subsistence slash-andburn farming systems