IDEAL FERTILIZERS 51 



meal is expensive compared with other fertilizer mate- 

 rials and really should be used for stock feed, as about 

 ninety per cent, of its fertilizing value will be found in 

 the manure, that is, if the manure is properly saved. 



Castor Meal is organic, carrying ammonia in form of 

 nitrogen. It has practically the same availability and 

 value as a soil builder as cotton seed meal but is not so 

 burning and is repulsive to insects, therefore is to be 

 preferred as a fertilizer material. 



Dissolved Bone Black Though this material was once 

 bone, the organic matter has been entirely burned out 

 and it is a strictly inorganic fertilizer. It is the same 

 as superphosphate except it carries no iron and alum- 

 inum. 



Superphosphate carries phosphoric acid in water solu- 

 ble form, which is immediately fixed by chemical reac- 

 tion, though still perfectly available to plants. When the 

 phosphoric acid is used by a plant the lime combined 

 with it is left to sweeten the soil. This amounts to about 

 six per cent., but about sixteen per cent, more lime, is 

 in the sulphate of lime intermingled with the phosphate. 

 This sulphate of lime acts neither as base nor plant 

 food, but brings latent plant food, especially potash, 

 into availability. The lime in the sulphate also acts in 

 preserving the two to one ratio between lime and mag- 

 nesia. With the phosphate and sulphate of lime there 

 about one-and-a-half per cent, iron and aluminum 

 which are neither beneficial nor detrimental. Superphos- 

 phate is the most economical source of phosphoric acid 



