296 



SOILS AND MANURES 



ported into the United Kingdom from various countries 

 in 1907 : 



Country. 



Peru .... 

 Venezuela . 

 Uruguay 



Seychelles Islands 

 Iceland and Greenland 

 Other countries . 



Total 



Tons. 



26,107 



1,400 



689 



626 



486 



1,970 



31,278 



Composition. The composition of guanos is extremely 

 variable according to the conditions to which they have 

 been exposed. In the older deposits a certain loss of 

 organic matter by decomposition probably took place, and 

 the proportion of phosphates and other ash constituents 

 was correspondingly increased, without much loss of 

 nitrogen. In most cases the phosphates have increased 

 only in proportion to the amount of nitrogenous matter 

 removed, and it is generally found that those which are 

 richest in phosphates are poorest in nitrogen. 



The average proportions found in some of the well- 

 known deposits were as follows : 



All these are entitled to be classed as nitrogenous guanos, 

 and if the phosphatic samples be taken into account it 

 may be said, in general, that the proportion of nitrogen 

 varies from up to 20 per cent., phosphates from 



