The Fertilizer Debate in the 19th Century

As the vegetarian, vegan, and organic produce movements have gained popularity in the United States and around the world, many of the practices of modern agriculture have been called into question insofar as their potential impacts on people and the natural environment. Not exempt from these criticisms have been inorganic commercial fertilizers, on which farmers and consumers alike have differing opinions. With the fairly recent increase in organic farming, conventional commercial fertilizers are being compared to unconventional “green” alternatives. However, this discrepancy between uses of outside fertility to help tend the land has been a debate for much longer than mass-produced fertilizers were the norm.
In her book “Ecological Revolutions,” Carolyn Merchant follows the progression of humans’ interaction with our natural environment (specifically in New England) through the pre-colonial, colonial, and industrial periods of North American history. In chapter 6, entitled “The Mechanization Nature,” she discusses the beginning stages of what she describes as the “capitalist ecological revolution.” As farmers in the later 1700s and early 1800s began to shift the focus of their production from subsistence to a market-oriented view, they generally began to focus on a single crop, leaving soil repeatedly depleted of the essential nutrients for the growing of whatever their specialty may be. With this came problems with soil fertility and a need to find solutions to keep crop yields up. In hopes of finding the solution to this problem, chemists, geologists, and farmers alike fell into one of two predominate beliefs as to how to properly nourish crops similar to those of today: organic and inorganic.
Those in the organic camp, such as chemist and geologist Samuel L. Dana of Lowell Massachusetts, believed that that the growth of plants relied on a fundamental principle of life already in the soil known as humus (pronounced hue-mus). Humus is described by soil scientists as organic material that is in the process of decomposition but has not yet reached the point of stability at which it will no longer break down. This top layer of soil along with animal manure and urine as well as decaying vegetable and animal matter scattered accordingly would replenish and balance the soil’s nutrients as all the organic nutrients could be absorbed into the plants’ roots. In contrast, German chemist Justus Liebig and his contemporaries in the inorganic minerals camp argued that the only role of humus was providing carbon dioxide to the roots. Therefore, in their assertions, minerals such as phosphoric acid as well as bases like lime and magnesia had to be spread on the topsoil to keep a field productive. In his 1813 publication Elements of Agricultural Chemistry, Sir Humphrey Davy disagreed with Liebig and company when he asserted that these inorganic minerals could not actually be absorbed by the plants’ roots. German physician and chemist Albrecht Thaer further supported this view with his assertion that the inorganic elements of “dead nature” fed the living plant.
Chemical fertilizers eventually triumphed over the organic humus practice due to population growth and therefore the need for increased production, but this debate is a prime example of how history is repeating itself. In order to fully understand the debate today, it is important to understand from where it originated.

Animal Manure is a key source of organic fertilizer

Animal Manure is a key source of organic fertilizer

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