46 Fertilizers 



There are many other deposits of guano, but none has 

 been found which are so valuable as the Peruvian. 

 Ichaboe guano, for example, is at present exported, 

 though it is a fresh deposit, and is annually collected for 

 shipment. Bat guano found in caves in Mexico and in 

 some of the southwestern states is another example. 

 Both are inferior to Peruvian guano. They contain 

 less nitrogen and a very considerable amount of insoluble 

 matter, though the nitrogen is usually in a good form. 

 In the case of the latter, a considerable portion exists 

 as a nitrate. Owing to the very excellent results that were 

 obtained from the early use of guanos, many attempts 

 have been made to improve the lower grades obtainable at 

 the present time, by the addition of nitrogenous matter 

 of a higher rate of availability. These rectified or 

 fortified guanos, while containing nitrogen in good forms, 

 cannot entirely substitute the original guanos, owing to 

 the impossibility of adding forms identical with those 

 existing in the natural product. That is, the total con- 

 tent of nitrogen in a rectified guano may be the same as 

 in the genuine product, though the special forms and their 

 proportions cannot be simulated. The distinctive value 

 of the natural guanos is due to the fact that the nitrogen 

 existed in a number of different soluble compounds, 

 which became available at different times in the soil, 

 and thus constantly fed the plant with this element. 

 The fact that nitrogen guanos gave such good results is 

 an evidence of the advantage of introducing different 

 forms into artificial mixtures. 



It is argued that because of the very great value of 

 guanos, which consist very largely of the excrement 

 of fowls, that droppings of pigeons, particularly, and of 

 domestic fowls should also possess a high value, and for 



