SECTION V. PLANT AND ANIMAL REFUSE 

 OF VALUE AS MANURE 



Guano. The name " guano " is of Spanish origin, and was 

 originally applied to the dried excrements and waste of sea 

 birds. The accumulation of these residues, through many 

 ages on the coast and islands in rainless districts, produced 

 a material which is now known as guano. The original 

 guanos were rich both in nitrogen and phosphates. The name 

 " guano " is, however, also applied to deposits of similar 

 origin which have accumulated in districts where there is 

 much rain. In these rainy districts nitrogen constituents 

 have undergone considerable decomposition, and have 

 eventually been entirely washed out. There are several 

 very different types of guanos, some containing much nitro- 

 gen, and others being chiefly phosphatic. The name guano 

 is also sometimes extended to include various artificial 

 products, such as fish guano and even blood guano, but these 

 latter materials have little relationship to the original 

 material to which the name guano is properly applied. 



The earliest source of guano was from the islands of Peru. 

 This guano was brought to Europe by Humboldt in 1804, 

 but is believed to have been used locally from very early 

 dates. The main deposits of Peruvian guano are now 

 completely worked out. Guano was one of the most impor- 

 tant early teachers of agricultural chemistry : it commanded 

 very great confidence among practical farmers, because of 

 its rapid action, and because there were no other manures on 

 the market which supplied both phosphates and nitrogen 

 in a readily available form. The old Peruvian guanos owed 

 miich of their effectiveness to the varied states of availa- 

 bility of their constituents. Some of the best qualities of 

 Peruvian guano contained considerable quantities of rare 

 nitrogen compounds ; there has been recorded as much as 



