It may not be a suitable topic for polite dinner conversation, but it's a fact that the guanay cormorant has no equal when it comes to the value and purity of its droppings. Not that you're very likely to see this bird or its waste products now. But for more than half a century, its excretions were on everyone's lips, sometimes literally so.
In Quechua, the language of the Inca Empire, the word for this miracle excretion was huanu, but the word came to the West slightly garbled as guano, and so it has remained.
For centuries, coastal Peruvian farmers had been fertilising their crops with a fine yellowish powder scraped from a few offshore islands. The food plants that grew in their barren soils were bountiful, an agricultural miracle so remarkable that when Alexander von Humboldt and Aime Bonpland were on the coast at the start of the 19th century, they hurriedly acquired samples of the powder, although they had no idea of its provenance.
Back in Europe, the samples were passed on to the continent's leading chemists for analysis. They found the mysterious powder to be rich in both nitrogenous compounds and phosphates, but failed to appreciate its potential. So, for the time being, guano remained hidden in the ratified world of analytical chemists, its existence reported on just a few pages in a couple of scholarly publications.
As every green-fingered gardener and farmer knows, plants require a few key nutrients in order to grow and thrive. Among these, nitrogen and phosphorus are absolutely essential, the former for growth and the latter for photosynthesis. Although 78 per cent of the Earth's atmosphere is made up of nitrogen, plants can't assimilate it from the air. Instead, as with phosphorus, they take up nitrogen from the soil by assimilating the appropriate compounds.
Sustaining both the nitrogen and phosphorus levels in the soil has always been an uphill struggle for farmers, and they are constantly on the lookout for other sources to plough back into their fields. Before the 1840s, this meant using farmyard and recycled urban waste (mostly 'night soil') for nitrogen and crushed bones for phosphorus. But with population growth and urbanisation booming on both sides of the Atlantic, farmers suddenly found themselves staring at failing yields. The nightmare of soil exhaustion, as nutrient replenishment lagged behind uptake, was becoming a reality.
Turning guano into gold
In 1838, while guano languished in the European cabinet of curiosities, in Lima, two enterprising Franco-Spanish merchants, convinced of guano's magic ("the base manure could well be transformed into the purest gold") and its market, had samples sent to Liverpool, to a successful merchant named William Myers, who had farming interests. Myers handed it out to his farmer friends to experiment with.
The next harvest gave Myers the answer he was hoping for. English farmers, he told his friends in Lima, would pay a good price for this guano. And to show he meant business, Myers put up the money to get the trade rolling. Early in 1841, a ship laden with just over 2,000 tonnes of guano cleared the port of Callao in Peru bound for Liverpool.
The guano found its way to fields across the UK, where farmers cautiously experimented. One of the first to report their findings was James Johnston, professor of chemistry at Durham University. His 20-page article, 'On Guano', published in the 1841 Journal of the Royal Agricultural Society, reported favourably on the results from five farms where guano was tested against traditional manures. Farmers were encouraged to try it out for themselves in a scientific manner (which Johnston described in full detail) and to decide whether it was for them.
Rather remarkably for the time, the article ended on a worrying tone, a portent of a catastrophic future. As Johnston put it: "It does not appear, as some have been led to believe, that the supply of this substance on the coast of Peru is by any means inexhaustible. …