By Edward D. Melillo

This entry is part of the Discard Studies Compendium

19th century advertisement for guano.

In his 1862 novel, Les Misérables, French writer Victor Hugo bemoaned the squandering of Parisian night soil: “A great city is the most mighty of dung-makers. Certain success would attend the experiment of employing the city to manure the plain. If our goldis manure, our manure, on the other hand, is gold. What is done with this golden manure? It is swept into the abyss” (1915). Hugo’s lamentation was part of a wider nineteenth-century critique of the emerging “metabolic rift” between city sewers and country farms. With the rise of the sanitary metropolis and the emergence of input-intensive agriculture in Europe and North America, products that had formerly connected urban and rural nutrient cycles were reclassified as waste (Miller 2000; Alexander 1993; Murray 1999; Melosi 2000).

During the mid-1800s, imported commodity fertilizers like Peruvian guano (dried bird excrement) and Chilean sodium nitrate (NaNO3) rapidly superseded an array of urban contributions to agricultural fertility, such as poudrette (human excrement, dried and mixed with charcoal and gypsum), furnace ashes, ground bone, and dried blood from slaughterhouses (Wines  1985). In effect, agriculturalists replaced metropolitan detritus, which had formerly supplied farmers with key macronutrients for plant growth (nitrogen, phosphorus, and potassium), with nutrient-rich supplements from distant environments along South America’s Pacific Coast (Melillo 2012; Cushman 2013).

As the Industrial Revolution drew workers from rural land into cities, farmers on either side of the Atlantic came under pressure to produce higher yields with which to feed the expanding urban population (Peterson 1940). Agriculturalists responded by relying upon a newfound array of foreign materials, such as imported fertilizers, seeds, and machinery, to produce surplus meat, grains, fruit, and vegetables for an emerging working class. Karl Marx, who witnessed a concentrated phase of this transformation in both Europe and the United States, summarized the shift in 1857 by writing, “agriculture no longer finds the natural conditions of its own production within itself, naturally, arisen, spontaneous, and ready to hand, but these exist as an independent industry separate from it” (1857–1858).

During the twentieth and early-twenty-first centuries, the “metabolic rift” between cities and farms has only deepened. The advent of industrial nitrogen synthesis, an energy-intensive process that requires high temperatures and high pressures, has increased the global availability of commodity fertilizer (Smil  2001). It has also precipitated an array of new, and often unequal, relations across space. As philosopher and sociologist Henri Lefebvre claimed in The Production of Space, the commodification of natural resources exemplifies one of the central environmental “displacements” of capitalism, namely that “those commodities which were formerly abundant because they occurred ‘naturally,’ which had no value because they were not products, have now become rare, and so acquired value. They have now to be produced, and consequently they come to have not only a use value but also an exchange value. Such commodities are ‘elemental’ not least in the sense that they are indeed ‘elements’” (1991). As a result, small farmers in many developing nations struggle with the financial burdens that accompany dependence upon expensive imported agricultural inputs. Likewise, many societies struggle with the costly disposal of urban sewage and the effluence from sprawling, industrialized animal farms. Challenges remain to the safe recovery of human and animal manures as future fertilizers. Appropriate treatment facilities and regulatory safeguards are crucial to preventing the spread of foodborne illnesses and thwarting the contamination of crops with heavy metals. Even so, innovative policy makers and pioneering non-state actors are hoping to once again recover the fertile matter of “the most mighty of dung-makers” (Chen 2012; Gardner 1997).

The concept of social metabolism that emerged from nineteenth-century political economy has much to offer practitioners of Discard Studies. One of the most crucial innovations of this theory is its departure from culturally contingent, historically variable, and conceptually weak concepts like money and price. Instead, social metabolism analysis adopts more robust and universally equivalent metrics like energy, matter, embodied land (ecological footprints), or embodied labor. These alternative measures of material exchanges and flows reveal processes across time and space that would otherwise remain invisible. The inequalities of global trade, the displacement of environmental burdens onto impoverished populations and places, and the possibilities for recapturing waste streams as sources of renewable energy are among the factors that such a theory illuminates (see: Bellamy and Holleman 2014; Horborg 2009; Fischer-Kowalski and Haberl 2005; Kaïka 2005; Swyngedouw 2004; Gandy 2002; Tarr 2002; Foster 2000).


Victor Hugo, Les Misérables, trans. Isabel F. Hapgood (New York: Thomas Y. Crowell Co., 1915), 84.

Marx, Capital, 3 vols. (1867–1894; repr., New York: Random House, 1981), 3:949.

Benjamin Miller, Fat of the Land: Garbage in New York: The Last Two Hundred Years (New York: Four Walls Eight Windows, 2000);

Judd H. Alexander, In Defense of Garbage (Westport, Conn.: Praeger, 1993);

Robin Murray, Creating Wealth from Waste (London, Demos, 1999).

Martin V. Melosi, The Sanitary City: Urban Infrastructure in America from Colonial Times to the Present (Baltimore: Johns Hopkins University Press, 2000).

Richard A. Wines, Fertilizer in America: From Waste Recycling to Resource Exploitation (Philadelphia: Temple University Press, 1985), 3.

Edward D. Melillo, “The First Green Revolution: Debt Peonage and the Making of the Nitrogen Fertilizer Trade, 1840-1930,” American Historical Review 117 (October 2012): 1028–1060.

Gregory T. Cushman, Guano and the Opening of the Pacific World: A Global Ecological History (New York: Cambridge University Press, 2013).

Arthur G. Peterson, “Agriculture in the United States, 1839 and 1939,” Journal of Farm Economics 22 (February 1940): 98–110.

Karl Marx, Grundrisse: Foundations of the Critique of Political Economy (Rough Draft) (1857–1858; repr., London: Penguin Books, 1973), 518.

[8] Vaclav Smil, Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production (Cambridge, Mass.: MIT Press, 2001).

Henri Lefebvre, The Production of Space, trans. Donald Nicholson-Smith (Malden, Mass.: Blackwell, 1991), 329.

H. Chen, et al., “Utilization of urban sewage sludge: Chinese perspectives,” Environmental Science and Pollution Research 19 (June 2012): 14541463;

Gary Gardner, “Recycling Organic Waste: From Urban Pollutant to Farm Resource,” Worldwatch Paper no. 135 (August 1997), 159.

John Bellamy Foster and Hannah Holleman, “The Theory of Unequal Ecological Exchange: A Marx-Odum Dialectic,” The Journal of Peasant Studies 41 (March 2014): 199233;

Alf Horborg, “Zero-Sum World: Challenges in Conceptualizing Environmental Load Displacement and Ecologically Unequal Exchange in the World-System,” International Journal of Comparative Sociology50 (June/August 2009): 237-62;

Marina Fischer-Kowalski and Helmut Haberl, eds., Socioecological Transitions and Global Change: Trajectories of Social Metabolism and Land Use (Northampton, Mass.: Edward Elgar, 2007);

Maria Kaïka, City of Flows: Modernity, Nature, and the City (New York: Routledge, 2005);

Erik Swyngedouw, Social Power and the Ubanization of Water: Flows of Power (New York: Oxford University Press, 2004);

Matthew Gandy, Concrete and Clay: Reworking Nature in New York City (Cambridge, Mass.: MIT Press, 2002);

Joel A. Tarr, “The Metabolism of the Industrial City: The Case of Pittsburgh,” Journal of Urban History28 (July 2002): 511-45;

John Bellamy Foster, Marx’s Ecology: Materialism and Nature (New York: Monthly Review Press, 2000).