Soil exhaustion and agricultural revolutions Marx's writings on metabolism were developed during England's "second"
agricultural revolution (1815–1880), a period which was characterized by the development of
soil chemistry and the growth of the use of chemical
fertilizer. Foster argues that Liebig's work became more critical of capitalist agriculture as time went on. From the standpoint of nutrient cycling, the socio-economic relationship between rural and urban areas was self-evidently contradictory, hindering the possibility of sustainability: If it were practicable to collect, with the least loss, all the solid and fluid excrements of the inhabitants of the town, and return to each farmer the portion arising from produce originally supplied by him to the town, the productiveness of the land might be maintained almost unimpaired for ages to come, and the existing store of mineral elements in every fertile field would be amply sufficient for the wants of increasing populations.
Human labor and nature Marx rooted his theory of social-ecological metabolism in Liebig's analysis but connected it to his understanding of the labor process. In
Capital, Marx integrated his
materialist conception of nature with his
materialist conception of history. Fertility, Marx argued, was not a natural quality of the soil, but was rather bound up with the social relations of the time. By conceptualizing the complex, interdependent processes of material exchange and regulatory actions that link human society with non-human nature as "metabolic relations," Marx allowed these processes to be both "nature-imposed conditions" and subject to human
agency, a dynamic largely missed, according to Foster, by the reduction of ecological questions to
issues of value. == Writers since Marx ==