Manures and Manuring 151 



but it was not till 1840 that the first cargo reached Britain. Five years 

 later nearly 300,000 tons were imported, and enormous quantities arrived 

 annually, until soon after 1870 the supplies began to get exhausted. The 

 Peruvian guanos are now completely worked out, and supplies have to 

 be obtained from other sources, such as the coasts of Bolivia, Colombia, 

 and Patagonia, Australia, South-west Africa, and certain islands in the 

 Pacific. The importations now are small in comparison with those of 

 earlier times. In 1901 only 13,000 tons were imported, and in 1907, 

 31,278 tons of all kinds of guano. The original Peruvian guanos were 

 very rich in plant foods, containing 14 to 16 per cent of nitrogen, 12 to 

 14 per cent of phosphoric acid, and 2 to 3 per cent of potash. They were 

 thus "complete" fertilizers. Modern guanos, however, seldom contain 

 more than 10 per cent of nitrogen, and may contain as little as 2 per 

 cent. Purchasers should always insist on obtaining a warranty when 

 buying guano, and samples should be analysed from time to time to test 

 the manurial value. 



"Guanos are commonly divided into nitrogenous and phosphatic. Ni- 

 trogenous guanos are those which contain a considerable percentage of 

 nitrogen, generally over 4 per cent. They may also contain a large 

 percentage of phosphate. A recent sample, for instance, contained 6 '3 per 

 cent of nitrogen and 32 per cent of phosphate. Phosphatic guanos, on 

 the other hand, contain little nitrogen, generally from 1 to 3 per cent, 

 but they should contain a considerable percentage of phosphate. Usually 

 the phosphate is from 30 to 50 per cent, but samples containing as much 

 as 70 per cent are sometimes on the market" (The Standard Cyclopedia 

 of Modern Agriculture). 



Fish Guano. Soon after 1870, when the supply of Peruvian guano 

 began to fail, it was thought that fish refuse might be utilized for the 

 production of guano especially as the latter manure came from birds that 

 fed largely on fish. Although the methods of manufacture were at first 

 very crude, and a good deal of oil was incorporated with the manure, great 

 improvements have been effected in late years. Fish guano is chiefly valu- 

 able as a manure for its nitrogen and phosphates, the quantities of which 

 vary according to the kind of fish. The supply of nitrogen will be larger 

 in fish having plenty of flesh and little bone, while the phosphates will be 

 greater in fish having much bone and little flesh. There is also a small 

 quantity of potash and lime. The nitrogenous value varies from 7 to 16 

 per cent, according to the kind of fish and the process of manufacture. The 

 phosphates vary from 3 to 20 per cent. What is known as " white fish " 

 guano is made from the heads, bones, and waste of haddocks, cod, ling, 

 and other non-oily fish, and is superior to the guano obtained from 

 herrings. 



Seaweed. Various kinds of seaweed have long been used as manure 

 when obtainable in sufficient quantities round the coasts. The commonest 

 kinds are species of Laminaria and Fucus, the latter genus supplying two 

 well-known species met with almost everywhere, namely, F. vesiculosus 



