Figure 9.8

Anthropogenic soil. The soil shown here is a result of San Francisco’s mandatory composting ordinance. The city requires all residents and restaurants to compost food scraps and paper food wrappers. Since 1996, when the program was first implemented, over 1 million tons of topsoil have been made from this compost. Farmers often call this composted soil “black gold,” referring to both its color and how well their crops grow in it.