230 MANURES FOR TREES 



of France and Belgium, are all the products of 

 human excrements, and are used upon the land. 

 Under the author's direction, " native guano " has 

 been used with good results for a variety of crops. 

 Bones are phosphatic manures containing a 

 small percentage of nitrogen, and are useful for 

 sandy as well as other soils. They gradually 

 decompose in the soil — yielding their fertilising 

 constituents. The decomposition is quicker when 

 bones are in the form of bone meal — either raw or 

 steamed. Bones are sold as half-inch, quarter- 

 inch, or as bone meal. Bones contain in 100 

 parts : — 



Bone meal can been used as a top-dressing. 



Bones are also fermented, boiled and steamed ; 

 but by boiling and steaming they partly lose 

 their nitrogen — and consequently are not so 

 valuable as manures as raw and fermented bones — 

 although the phosphates are increased. 



Bone black is a valuable manure obtained from 

 sugar refineries. It contains carbon in addition to 

 lime phosphate and nitrogen. It is useful for 



