PHOSPHATE FERTILIZERS 2O/ 



235. Guano is the Spanish for dung and is a concen- 

 trated form of nitrogenous and phosphate manure, of in- 

 terest mainly on account of its historic significance. It 

 is a mixture of sea-fowl droppings, with dead animals and 

 debris, which have accumulated along the seacoast in 

 sheltered regions and undergone fermentation. The 

 introduction of guano into Europe marked an important 

 period in agriculture, inasmuch as its use demonstrated 

 the action and value of concentrated fertilizers. All of 

 the best beds of guano have been exhausted and only a 

 little of the poorer grades is now found on the market. 

 The best qualities of guano contained from 12 to 15 per 

 cent of phosphoric acid, 10 to 12 per cent of nitrogen, 

 and from 5 to 7 per cent of alkaline salts. 



BONE FERTILIZERS 



236. Raw Bones contain, in addition to phosphate of 

 lime, Ca 3 (PO 4 ) 2 , organic matter which makes them slow 

 in decomposing and slow in their action as a fertilizer. 

 Before being used as a fertilizer they should be fer- 

 mented in a compost heap with wood ashes in the follow- 

 ing way, a protected place being selected so that no losses 

 from drainage will occur. A layer of well-compacted 

 manure is covered with wood ashes, the bones are then 

 added and well covered with ashes and manure. From 

 three to six months should be allowed for the bones to 

 ferment. The large, coarse pieces may then be crushed 

 and are ready for use. The presence of fatty material 



