MANURTAL VALUE OF ASHES, "MUCKS," ETC. 85 



is soluble in water and makes the water soluble phosphoric acid 

 of commercial fertilizers. While the other phosphate is not 

 soluble in water, it is readily available to plants. This is the 

 so-called "reverted" phosphoric acid. The water soluble and 

 the reverted together make up the "available" phosphoric acid of 

 commercial fertilizers. The original prosphate of lime becomes 

 very slowly available as a plant food, while the acidulated phos- 

 phate is speedily and completely available. Most of the acidu- 

 lated phosphate used in the manufacture of fertilizers is not 

 obtained directly from bone, but from bone ash and bone black 

 or from phosphatic rocks, which occur in South Carolina, Florida 

 and other southern states. The acidulated phosphate from rocks 

 is called "dissolved rock" while that from bone ash is called 

 "dissolved bone black." While dissolved bone black commands 

 a higher price than dissolved rock, there is no evidence that the 

 acid phosphate prepared from bone ash is superior as a fertilizer 

 to the acid phosphate from "rock." Bone ash which has not 

 been acted upon by sulphuric acid has comparatively little value 

 as a fertilizer. 



BONE MEAL. 



Bone meal differs materially from bone ash, because of the 

 ossein (nitrogenous material) which it contains. When bone 

 meal is buried in moist earth the flesh-like ossein putrifies and its 

 nitrogen becomes available to the growing plant. In its decay 

 the ossein helps somewhat to dissolve the bone phosphate of lime 

 and renders it available. The rapidity of the decay of bone is 

 largely dependent upon its fineness. The Connecticut Experi- 

 ment Station has adopted an arbitrary scale upon which is 

 based the trade valuations of ground bone. Meal that passes 

 through a sieve of one-fifteenth inch mesh is called "fine" and 

 that which will not so pass is termed "coarse." They value the 

 nitrogen in fine bone and tankage at fourteen cents a pound and 

 in coarse at ten cents. They rate phosphoric acid in "fine" bone 

 and tankage at four cents a pound and in coarse at two cents. 



Bone meal has been used for many years in England and Ger- 

 many where its effects have been carefully studied. These 

 investigations show that bone meal does its best "upon soils that 

 are neither too light and dry nor too close and wet," and that it 



