44 Fertilizers 



it may be secured in abundance without cost of trans- 

 portations. Furthermore, its use as a food for cattle is 

 becoming more thoroughly understood and appreciated 

 so that its use as a fertilizer is decreasing. 



Linseed meal is a material somewhat similar in 

 character to cotton-seed meal. It contains on the 

 average 5.5 per cent of nitrogen. The demand for 

 this product for feeding purposes at good prices makes 

 it, however, an expensive source of nitrogen. 



Castor pomace, the waste resulting from the extraction 

 of oil from the castor bean, is also a valuable nitrogenous 

 fertilizer. It contains, on the average, 6 per cent of this 

 element, and decays rapidly in the soil. This product 

 differs from the cotton-seed and linseed meal, in that it is 

 not useful as a cattle food. Practically its only use is 

 as a fertilizer. 



Vegetable pomaces. There are a number of pomace 

 materials of local interest, including apple pomace, tomato 

 pomace, pumpkin pomace, cranberry pomace and the 

 like, which are used to a considerable extent by a few 

 individual farmers. These materials are very variable 

 in composition. They are usually used without drying 

 and the content of moisture is almost never constant. 

 Most of, these products are derived from fruits or vege- 

 tables very acid in character and the acid contained is 

 often in large enough quantities to be injurious unless 

 composted with dirt and slaked lime. 



NATURAL GUANOS 



A series of nitrogenous products which constitute still 

 another separate class, consists of the various natural 

 guanos. From its derivation the word " guano " means 



