50 FERTILITV AXD FERTILIZER HINTS 



rainless and has a dry hot temperature, these remains dry out 

 rapidly and are preserved without much loss of phosphoric acid 

 or nitrogen. There is some loss of nitrogen in these Pe- 

 ruvian guanos due to the formation of ammonium carbonate, 

 a volatile form, and to leaching by occasional rains. However, 

 these deposits have been the best nitrogenous guanos in the world. 

 There are deposits in other parts of South America, West Indies, 

 Africa, Australia, Asia, and the islands of the Pacific, but the 

 Peruvian deposits are the most notable. There is a wide differ- 

 ence in the composition of guanos. Tn Peru, guano from the 

 same island shows variation in chemical composition, while guano 

 from different islands shows even a greater variation. The old- 

 est deposits usually contain less nitrogen and more phosphoric 

 acid than the more recent. In a wet, damp climate, fermenta- 

 tion, aided by the presence of moisture, destroys all or most of 

 the organic matter driving off the nitrogen as ammonium carbo- 

 nate. Soluble phosphoric acid is also lost in such regions. 

 Therefore it is easy to understand the wide differences in the 

 composition of these deposits. 



Guanos range from rich nitrogenous deposits to phosphatic de- 

 posits which only contain traces of nitrogen and considerable 

 amounts of phosphate of lime. There are therefore two classes 

 of guanos, namely, nitrogenous and phosphatic. The phosphatic 

 guanos will be discussed under phosphates. 



Formerly guano was used more extensively in the United States 

 but most of the nitrogenous deposits have been exhausted so that 

 the importations are rather decreasing from year to year. There 

 were 16,155 tons imported from Peru in 1905 and 5.500 tons in 

 1909.^ 



The nitrogen in guanos is present in different forms. Some 

 of it is as nitrates, some as ammonia and some as organic nitro- 

 gen. The presence of these various forms makes the nitrogen- 

 ous guanos valuable because they supply plant food during the 

 whole growing season.* 



In Mexico there are deposits of bat guano, many of which are 

 good nitrogenous fertilizers, but they are not being worked be- 



• 1910 American Fertilizer Handbook. 



