Nitrates | United States (1867)

1382155-6405352 - Howe Holly - May 4, 2016 1052 AM - Howe_anthropocene object_image

Dynamiting crows, available under CC 4.0 at http://uwdc.library.wisc.edu/

By Holly Howe

The relationship between humans and nitrates is long and convoluted, and the changing nature of that relationship is a meaningful way to periodize history. A dominant narrative of the Anthropocene is the perceived struggle between human mastery of nature and the limits that nature imposes on the march of progress. The pursuit, production, and consumption of nitrates exemplifies this conflict. Nitrates have influenced the course of world history, and their role in the Anthropocene shapes our shared future.

Nitrogen is as necessary to life as water and oxygen. It is the key component of amino acids, the building blocks of proteins which perform countless functions in the structure and physiology of all organisms. The largest nitrogen reservoirs are the atmosphere and the oceans (Royal Society of Chemistry). When nitrogen is in its diatomic form, it must be incorporated into larger molecules, namely ammonia, in order for plants and animals to use it. This process is called fixation and occurs naturally by lightning strikes and by certain soil microbes that associate with plant root systems (Postgate 1998). Under the biological old regime, humans relied entirely on solar energy inputs into the ecosystem for their survival. Hunting, gathering, and pre-industrial agriculture all depend on resources that are in constant flux with the seasons and with weather events such as El Niño. Nitrate availability was balanced between uptake by plants and inputs of decaying organic material and fixation of nitrogen by soil microbial communities (Marks 2007). The density of edible plants on the landscape and the animals that consume them is dependent on nitrate availability, which limits the size of hunter-gatherer populations. Attempting to grow more crops than a plot can sustainably produce depletes nitrates and results in soil exhaustion (Marks 2007).

Human populations were limited in size by naturally available levels of nitrate, but for centuries they have increased soils’ productive capacity by artificially increasing nitrate inputs. The Romans exported waste from cities to outlying farms to help feed growing urban populations. Pre-Colombian societies in the Amazon Basin used their waste and burnt organic matter to improve the productivity of nutrient-poor rainforest soils, transforming them into terra preta or “black earth.” In 1802, Alexander von Humboldt introduced the European scientific community to guano, which he observed being used as fertilizer in Peru. This began the Guano Age, where nitrate-rich guano mined in Chile, Peru, and nearby coastal islands fueled an intensification of European agriculture (Cushman 2014). Enriching soil with nitrates allows a relatively large population to survive on a restricted plot of land permanently, without migrating to allow natural vegetation to regrow and replenish the soil nitrates, as early agrarians did, or letting fields lay fallow while planting others, as feudal Europeans did (Smil 2004). These techniques were steps in the path away from direct reliance on solar energy and natural nutrient cycles.

The Haber process, developed in 1909 and improved in 1913 by Charles Bosch, marks another key departure from the biological old regime (Bown 2005). The Haber-Bosch process is a chemical reaction by which atmospheric nitrogen and methane gas are combined under high pressure, resulting in ammonia. Ammonia is a good source of fixed nitrogen and can be applied directly to the soil as a fertilizer or transformed into ammonium nitrate, urea, or nitric acid (Smil 2004). The applications of the Haber-Bosch process were primarily in chemical weapons and explosives during World War I, especially in Germany, where the process was developed and where typical nitrate sources such as Chilean saltpeter were scarce after an Allied trade embargo (Jones 1920).

Nitrates are also used to make nitroglycerin, the explosive ingredient of dynamite. Dynamite was invented by Alfred Nobel and patented in 1867 (Alexander 1920). It is primarily used in civil engineering, but also has agricultural applications. Dynamite blasted tunnels for transcontinental railroads worldwide and channels for the Suez, Eerie, and Panama canals (Bown 2005). Du Pont, a dynamite manufacturer until the mid-1970s, published a handbook advertising their product’s many uses to farmers. They recommended dynamite to clear-cut land, till soil, cultivate trees, and irrigate fields (E. I. Du Pont de Nemours 1912). Dynamite was widely used for these purposes and also to manage agricultural pests. Farmers in the 1930s and 40s in the United States used dynamite to kill flocks of crows and other pest birds, and then plowed the carcasses into the fields to fertilize them (Markland 2016). Farmers today in sub-Saharan Africa blast flocks of quelea, also called the locust bird for the devastation it causes (IRIN 2012). Although widely employed and viewed positively in the past, using dynamite to reshape landscapes and ecological communities has devastating consequences. Dynamite fishing destroys reefs and involves massive catch: it particularly affects juvenile fish, severely reducing the viability of the population (Westmacott 2000). In terrestrial biomes, dynamite blasts obliterate the existing plant community and expose bare soil and rock, leaving ecological niches open for early successional species that are usually invasive. This permanently alters the ecosystem from its original state, creating a new ecosystem that is usually less biodiverse, more susceptible to degradation, and are less productive than older ecosystems (Grace et al. 2016).

The effects of human nitrate use on threatened ecosystems are not limited to such obviously destructive methods as dynamite. Agricultural run-off, polluted with nitrates from pesticides and animal waste, drains into groundwater, rivers, lakes, and streams. The nitrate-rich influx boosts the growth of photosynthetic organisms in the water, creating algal blooms. As the short-lived photosynthetic organisms die, their decomposition uses up oxygen until the water becomes anoxic (Bruckner 2012). This process of eutrophication leads to die-offs such as the one ongoing in the Gulf of Mexico due to agricultural run-off in the Mississippi River. Most multicellular organisms cannot survive with such low levels of oxygen, so there are massive die-offs of the mollusks, crustaceans, and fish that local people depend on for income and subsistence (Bruckner 2012). The effort to feed growing human populations by decoupling production from the natural nitrogen cycle has, in fact, severely destabilized that same cycle for other people.

The history of nitrates in the Anthropocene is a familiar story: striving to expand upwards and outwards has left humans on shaky footing. As we look back on our past relationship with the nitrogen cycle, we can frame our departure from the biological old regime as a technological marvel that has allowed growth and development we never could have achieved otherwise. In this context, the looming crisis of nutrient pollution is a problem to be addressed with more efficient fertilizers or containment of run-off. We may imagine ways to construct a nitrogen cycle in space stations and apply our technological knowledge to further detachment from the earthly cycle we have thrown off course. Perhaps a better way to conceive of our relationship with nitrates in the Anthropocene is not as a struggle for growth unfettered by natural limits, but as changes to people and places contingent on their historical contexts. By re-coupling the broken connection between people and their local nutrient cycles, by re-imagining our relationship with nitrates in an informed and globally-mindful way, those changes can be for the better after all.

Works cited

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Markland, Ben. “3,000 Crows Slaughtered with Dynamite.” Chicago Daily Tribune 18 Jan. 1936: 21. Chicago Tribune. Web. 19 Apr. 2016. <www.archives.chicagotribune.com>.

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“Nitrogen.” Royal Society of Chemistry: Periodic Table. Accessed April 20, 2016. http://www.rsc.org/periodic-table/element/7/nitrogen.

Postgate, John. 1998. Nitrogen Fixation. Cambridge, UK: Cambridge University Press.

“Quelea: Africa’s Most Hated Bird.” IRIN. August 19, 2009. http://www.irinnews.org/news/2009/08/19.

Smil, Vaclav. 2004. Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production. Cambridge, MA: MIT Press.

Westmacott, Susie. 2000. Management of Bleached and Severely Damaged Coral Reefs. IUCN.