Inspired by the fertility and climate change-mitigation properties of the so-called Amazonian Dark Earths (ADEs), soil science has devised a technoscientific replica, a soil amendment known as biochar, intended to improve agricultural sustainability and carbon storage in the biosphere. Drawing on fieldwork with Afroindigenous horticulturalists, this article shows, however, that the activation of these soils' vibrant ecology responds to looping, carbonic, and socially mediated forms of human and other-than-human corporeal interplay. With an ethnography of swidden horticulture in Amazonia, I propose the notion of 'somatosoils' to consider that the fertility and other metabolic properties of ADEs might be located not in the soil, but in the relations between the earth's bodies and the specific human gestures that stimulate these soils' inner life.
Introduction: Carbonic relationsDespite the common imaginaries of the rainforest, the Amazon basin is not exactly a fertile environment. The exuberant Amazonian vegetation is composed of species that have specialized in quickly capturing nutrients from highly weathered soils. Heavy rainfall, among other factors, leaches organic matter from the earth on a daily basis, resulting in acidic and unfertile soils. And yet Amazonia is far from homogeneous in ecological terms. An important exception to the standard low fertility is found on the patches of the so-called Amazonian Dark Earths (henceforth ADEs). These soils, which are rich in organic carbon, have gained scientific attention since Dutch scientist Wim Sombroek (1966) outlined their importance not only for sustaining small-scale agriculture in Amazonia, but also as a 'model' for developing agricultural tools that could help to sequester carbon in the biosphere on a planetary scale.Today, both soil sciences and archaeology recognize the anthropogenic genesis of ADEs in pre-Columbian settlements (Denevan 2001;Erickson 2003;Schmidt 2013). For millennia, the fertility of certain rainforest soils has been enhanced -though not always wittingly -through human practices that have led to accumulated charred wood, decomposing vegetation, animal carcasses and bones, and faeces, thus originating