Just as the fossil fuel use that has provided most of the world’s electricity and mobility has rearranged the planet’s carbon cycle, so the drive to fertilise has upended its nitrogen cycle
was founded, a rich English farmer, Sir John Lawes, started a long-running experiment in a field called Broadbalk. Both beginnings were driven by concerns about wheat.wanted tariffs on wheat imports which benefited English landowners—the Corn Laws—lifted so that free trade could bring down the price. Lawes wanted those landowners and their tenants to be more productive, and thus more competitive, and to make money by helping them become so.
When Lawes began his experiment at Broadbalk he was particularly interested in the benefits of a fertiliser produced from bones and sulphuric acid known to work in rich soils, and which Lawes was producing for sale at a works in London. The Rothamsted work showed that, on its own, the concentrated phosphorus in this product did little.
There are, however, some basic biochemical constraints; life needs a great deal of nitrogen; and fixing that nitrogen requires a lot of energy. Bacteria are far better chemists than Haber, Bosch or any of their human successors. The catalyst they use to fix nitrogen, a protein called nitrogenase, has been fashioned by evolution to do so without high temperatures and pressures, twisting and coaxing the molecules apart rather than breaking them with brute force. That said, it is complex to make, fussy about its working conditions and an energy hog; keeping it going requires a lot of metabolic juice.
In 1840 the Peruvian Republic granted Don Francisco Quiroz, president of the Lima chamber of commerce, a monopoly on the exploitation of the guano on the shittiest of its islands, the Chinchas. He was backed by British and French investors who knew that men of science, such as the current’s namesake, Alexander von Humboldt, spoke highly of the stuff.unloaded the first reeking cargo of guano in Liverpool; all told, 8,000 tonnes were imported that year.
As for nitrogen, most came from mineral deposits in the Atacama Desert, not that far from the guano islands off Peru. In 1879 competition for control of the nitrate deposits saw a war break out between Bolivia, Chile and Peru. Chile won, and for the rest of the century it completely dominated trade in fixed nitrogen.
That made the fixation of atmospheric nitrogen “one of the great discoveries awaiting the ingenuity of chemists…vital to the progress of civilised humanity”. On the basis of the latest figures from Rothamsted he calculated that eventually as much as 12m tonnes a year would be needed. The effects of industrially produced nitrogen fertilisers were not so quickly felt. By the 1930s Billingham, a wonder when opened the decade before, had come to be seen as a drain on’s resources. The gains in agricultural productivity seen in the first half of the 20th century mostly came from the mechanisation of field work by tractors, combine harvesters and the like.
The natural nitrogen cycle balances itself; over time the amount of nitrogen fixed from the atmosphere by bacteria equals the amount of nitrogen stripped out of compounds in the soil and water and returned to the air as NIn their eagerness to fertilise the land humans substantially increased nitrogen fixation around the world while doing nothing to increase the rate of denitrification: it currently runs at only 40% or so of the rate at which nitrogen is added to the environment.
One overarching aspect of this superabundance is the reduction of biodiversity. Dr de Vries reckons that nitrogen deposition is, after habitat destruction and climate change, the third greatest destroyer of biodiversity in the world. A principal reason for this is that some plants are better at using nitrogen than others. If nitrogen levels are increased the plants that are good at using it get a bigger boost than the rest, and outcompete them.
After the famine the Netherlands suffered during the last winter of the second world war, boosting food production became a national priority, and that urgent desire for self sufficiency produced farms that could expand on the country’s historical success as a dairy exporter. Today the Netherlands, which houses roughly 0.1% of the world’s cows on just 0.008% of its land surface, produces 4% of its cheese.
But it is a particular instance of a pervasive set of issues: how to deal with the fact that human politics and regulations are now intimately involved in the flows of the fundamental stuff of life on a scale that has impacts throughout the living world. The archetype of these issues is that of carbon dioxide. Yet it is also, at the moment, a conceptually simple one; the primary prescription is to decouple human industry from the carbon cycle by renouncing fossil fuels.
Giles Oldroyd, who leads an effort to this end at Cambridge University, sees it as a question of setting up a dialogue between forms of life divided by billions of years of evolution. That gives the science a pleasing symbolic resonance with its possible application, breaking down the binary of plant and bacteria in order to help bridge the rift between natural and industrial.
Belgique Dernières Nouvelles, Belgique Actualités
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