ROOTS 107 



the end of a month? What must be inferred from the re- 

 sults of this experiment? 



Origin of Some Fertilizers 



1. The commonest fertilizer in use is stable manure. It 

 is prepared by piling in heaps, where a sort of fermentation 

 takes place. When the mass has been reduced to a dark 

 color and heat has ceased to be generated, it is ready for 

 use. 



2. Guano is a fertilizer imported from the rocky islands 

 on the Pacific coasts of South America. It consists of bird 

 manure, eggs, bones, decayed remains of fish, birds, etc., 

 which have accumulated where the birds have their breed- 

 ing grounds. It resembles a grayish black soil and is a 

 very rich fertilizer. 



3. Phosphate earth is classed as a mineral fertilizer, but 

 it is in reality of animal origin, being composed of the fossil 

 remains of fishes and other animals of long ago. The phos- 

 phate beds of the Carolmas are the principal source of this 

 fertilizer. 



4. Chile saltpeter is a mineral found in many parts of the 

 earth, where it is mined. The greatest exporter of this sub- 

 stance is Chile, hence the name. 



5. Wood ash, although obtained from plants, is a mineral 

 substance. It is rich in potash. 



6. Lime is not itself a plant food, but it owes its chief value 

 to the fact that it decomposes many organic substances, 

 causing them to give up ammonia, which is a valuable ferti- 

 lizer. If a little lime is put into a test tube together with 

 any animal substance and heated, the familiar odor of 

 ammonia will be quickly detected. 



A good nutrient solution for plants may be made by mix- 



