The New Student's Reference Work/Guano and Guano Islands

Guano (gwä′nō) and Guano Islands. Guano is the deposit of sea-fowl, found in immense quantities on certain coasts and islands where the climate is dry and free from rain. Its value in agriculture was well-known to the Peruvians long before the coming of the Spaniards. Alexander von Humboldt first brought specimens of guano to Europe in 1804. There are three classes of guanos: (1) those which have suffered little by the action of the air, retaining nearly all of their original matter, such as the Angamos and Peruvian guanos; (2) those which have lost a considerable portion of their soluble matter, but remain rich in their less soluble ones — the phosphates of lime and magnesia, as the Ichaboe, Bolivian and Chilean guanos; and (3) those which have lost nearly all their ammonia and contain but little more than the earthy phosphates of the animal deposit; in this last class must be placed the various African guanos and the West Indian, Kuria Muria {islands off the coast of Arabia), Sombrero, Patagonian and Shark's Bay guanos (Australia). Most of the so-called Peruvian guano has been obtained from the Chincha Islands off the coast of Peru. These are three small islands, often called the Guano Islands. Here multitudes of penguins and other oceanic birds build nests and breed, and large deposits of guano have accumulated. Not one of these islands covers more than a mile. They are rocky cliffs, some 300 feet high, with many caves into which the waves dash. The whole supply of guano on these islands is now exhausted.

If the value of manure be calculated, as is done by chemists, according to the amount of nitrogen which it contains, one ton of good Peruvian guano is equal to 33½ tons of farmyard manure. Its value as a manure has become so well known and its use is so great, that it is gradually being used up.

Fish-guano is dried fish ground to powder. Mussels, five-fingers or starfish, herrings and particularly sprats are mostly used in this way. In 1862 the refuse of the Norwegian cod-fisheries was first used by drying the heads and backbones upon heated floors after sun-drying them on the rocks, then grinding them to powder between mill-stones. Fish-guano has grown rapidly in favor of late years among farmers, the supplies of guano proper being practically used up, and is the best-known substitute for the Peruvian guano. One ton of fish guano is said to be equal to 17 tons of farmyard manure. Guano is made in Canada and elsewhere from lobster and crab shells, which is said to be very valuable for gardens. The annual production of fish-guano from all sources, England, Scotland, Norway, Sweden, Newfoundland, Nova Scotia and the United States, is estimated at 75,000 tons.