That plants need nutrients has been known pretty much as long as humans have been growing them, but it was not until the 1840s that Justus von Liebig identified the role of nitrogen.
Prior to artificial fertilisers, farmers would typically use plant nutrients mainly from sources such as faeces and urine.
Then, in 1903, Norwegian scientists Kristian Birkeland and Sam Eyde built a factory to produce nitrogen fertiliser based on principles discovered by Henry Cavendish in 1784.
Because the process required large amounts of energy and was inefficient, they built their factory next to a Norwegian hydroelectric power station.
Although it was an advance, it wasn't viable at scale and the growing demand for nitrates during the 19th century had to be sourced by mining niter and guano deposits.
This caused environmental devastation on islands such as Nauru, that included the destruction of bird habitats.
Fortunately, nitrogen is the most abundant gas in the atmosphere and in 1909 Fritz Haber and his assistant Robert Le Rossignol discovered a more efficient way to produce ammonia from the air.
By this time, ammonia had become crucial for industry as well as agriculture. Recognising the potential, the German chemical company BASF purchased the process.
They assigned Carl Bosch to investigate a way to operate it on an industrial scale.
By the outbreak of World War I, BASF's plant in Oppau was manufacturing 20 tonnes of ammonia per day.
Until that time, ammonia was needed primarily for growing crops, but now it became essential to the German war effort.
While the Allies had access to large deposits of sodium nitrate that could be mined, the Germans did not.
This meant that synthetic ammonia from the Bosch plant was now crucial for making explosives. Without it, they would've faced defeat within months.
Today, a form of the Haber-Bosch reaction is still used. And, although it captures nitrogen from the air, hydrogen is mostly sourced from natural gas.
Hopefully this can be replaced by "green" hydrogen, but it is not currently cost competitive. It's an urgent mission because in 2018 global production of nitrogen fertiliser was 117.5 million tonnes and will continue to grow along with the demand for food.
The Fuzzy Logic Science Show is at 11am Sundays on 2xx 98.3FM.
Send your questions to AskFuzzy@Zoho.com; Podcast: FuzzyLogicOn2xx.Podbean.com
