Eating Minerals: Fossil Inputs in 18th Century Agriculture

This is the 2nd in a series of posts written by recipients of a NiCHE New Scholar Travel Grant to attend the World Congress of Environmental History in Guimarães, Portugal.

Modern agriculture is energy intensive, relying upon heavy machinery, petroleum-based fertilizers, long distance trade networks and electric-powered processing plants. In 1996, Canadian agriculture used 7,129.1 PJ of various energy inputs, or 247,136,931 kj/Canadian. This was 67 times the energy required to provide every Canadian, including infants, with a 10,000kj/day (2,388kcal) diet. Agricultural energy use appears absurd when stated as such.

The energy intensity of contemporary agriculture inspires nostalgia for a time when vegetable gardens and grain fields converted more solar radiation to usable energy than the labour required to harvest them. It also evokes a golden age when food was eaten locally and motivates the local food movement. However, this idyllic vision of the local food movement does not entirely correlate with historical reality. Our global population of 7 billion is substantially larger than at any previous era and diets are generally better than those of previous generations. Moreover, fossil inputs have been helped increase agricultural productivity for centuries.

I am a historian of Industrial Revolution Yorkshire, when lime and coal ash were important soil amendments. Lime is the fossilized remains of shells and the processing of converting limestone to agricultural lime involved considerable heat. In fact, coal was the largest cost in eighteenth-century lime processing. Lime and coal ash are both used to increase the pH levels of soils but do not directly provide nitrogen. As such, they improve the fertility of acidic soils. Draining wetlands generally leads to some minerals leaching out and their acidification. Lime and coal ash were particularly useful soil amendments in those locations.

At the upcoming World Congress in Environmental History, I will be discussing the use of lime and coal ash in Yorkshire between 1770 and 1830. Both have been used in the region since at least 1500 but the scale expanded significantly with industrialization. As a by-product of burning coal, more ash became available as Yorkshire coal consumption tripled between 1775 and 1830. The West Riding of Yorkshire consumed at least 750,000 tons in 1775 and over 2.3 million tons by 1830. Some of this coal was used to cook food for an expanding population, as it rose from 390,000 in 1771 to nearly a million residents by 1831. The coal was also used in various manufacturing processes like boiling cloth dyes, baking pottery, heating metals to shape cutlery and powering the first steam-engines in linen-textile factories. Ash was generally used near where the coal had been burnt, in particular in the vegetable and market gardens which surrounded industrial towns like Leeds, Bradford and Sheffield. Interestingly, the bituminous coal burnt in such towns had a high sulphur concentration and their immediate surroundings began to suffer from acid rain in the 1810s and 1820s. Applying ash to vegetable gardens helped to rebalance the pH of those soils and limited the impact of acid rain on plant growth.

Unlike coal lime, lime was mined, processed and transported on a commercial scale in eighteenth-century Yorkshire. The main lime deposits were in the hilly western portions of the county, near the coal. Transporting lime to the flatter eastern regions better suited to grain cultivation required canals and river navigations. In fact, connecting such regions and facilitating the lime trade was one of the main motivations for the Leeds and Liverpool Canal, pictured above. This canal began construction in the early 1770s and made it economically feasible to ship lime around the county. Shipping lime to arable regions helped increase the productivity of acidic soils, which were especially prevalent in recent drained wetlands. The same canals also served to ship coal to agricultural regions and grain west to feed people in the manufacturing district where the coal and lime originated. This grain allowed more people to live in manufacturing towns and helped to break their reliance on purely local resources. In this way, canals and the lime they carried were part of a larger development towards regional economic specialization and a reliance upon non-local food. Like coal ash, they also inherently relied upon fossilized energy reserves and counter simplistic ideals of local diets in the pre-railroad era.

The larger research that this draws upon will be presented as part of two panels at the World Congress of Environmental History on Energy on Agro-Ecosystems on the morning of Friday, July 11 in room G-2. Other papers will discuss the increasing energy intensity of agriculture between 1800 and 2000 in Catalonia, Mallorca, Andalucía, France and Austria. These fascinating papers should help us better understand one of the most fundamental transformations in human society and our relationship with the non-human world. The complete version of my paper is also available upon request (dbzylber@yorku.ca).