Every fact about the Sun is hard for most of us to take in. The numbers are so huge it makes us and our Earth seem very small and insignificant. When we feel the heat of the Sun on our face, it is hard to believe that it has come from 150 million km away. Just a tiny fraction of the Sun’s energy hits the Earth, yet every minute enough energy arrives to meet our demands for a whole year if only we could harness it properly.
The population of the Earth has always gone up in line with our ability to provide sufficient food and it could be argued that the population explosion of the last 60 years has been possible in large part because of artificial nitrogen fertilizer.
Good crop growth depends on sufficient soil nitrogen, and in the past farmers spread manure,and used nitrogen fixing crops such as peas, beans and clover to replenish reserves. There was also imports of guano and other nitrogen rich natural deposits.
The real breakthrough came in the early twentieth century when the german chemists, Fritz Haber and Carl Bosch invented a way to use hydrogen to capture atmospheric nitrogen and form ammonia.
The application of large amounts of nitrogen fertilizer has boosted yields to such high levels that Professor Vaclav Smil of Manitoba University estimates that ‘without nitrogen fertilizers no more than 53% of today’s population could be fed at a generally inadequate per capita level of (year) 1900 diets’.
The green revolution, using high yielding new crop verieties would have been impossible without nitrogen fertilizer produced this way but has the world population expanded on the back of an unsustainable method.
The process needs vast amounts of energy which has been mainly provided by cheap natural gas and the production of nitrogen is responsible for a large part of farmings carbon emission. We know that gas supplies will eventually decline and become expensive, probably causing a switch to using coal as the feedstock, which would be much worse for carbon emissions at a time when world leaders are commiting us to huge reductios in all greenhouse gas emissions.
We could say that the availability of cheap nitrogen fertilizer has allowed the massive overpopulation of the world and that when it becomes much more expensive as demand outstrips supply, nitrogen shortages will contribute to peak food.