No. 4.] COMMKKCIAL FERTILIZERS. 119 



original ('oiiditioii, or when coarsely ground, is likely to 

 decay. Farmers from the earliest times have used animal 

 bone, — we have references in both ancient and medineval 

 history to the nse of bone for certain crops, and our econom- 

 ical ancestors in this country also made a practice of saving 

 and iisini;; the Ixiiics wliieli acciiiimlalecl in the household, 

 placing them about the roots of fruit trees, of grape vines, 

 currant bushes, etc., knowing that they would supply the 

 needed sustenance, but not knowing the reasons why. 



In more modern times, l)ecause of this knowledge, inherited 

 and acquired by ex])erience, many farmers prefer to use the 

 phos})hates derived from bone rather than those derived from 

 phosphate rock, even if in the latter the availability may be 

 very largely increased. This general experience, and this 

 prejudice in favor of bone, has its foundation in science; or, 

 in other words, scientific investigation of this substance has 

 revealed the reasons, in part at least, for such belief. Per- 

 haps the best statement tliat can be used to express the reason 

 diiferences in result are secured from these two classes of 

 phos]>hate, or ground bone and rock superphosphates, is " that 

 ground bone is never poorer than tlie day it is applied, — its 

 tendency is to decay and thus become more available as time 

 goes on, whereas, in the case of superphosphates, it is never 

 better than the day it is applied," for the tendency is to re- 

 vert to the naturally insoluble condition. In the case of the 

 bone the effect is lasting; in the superphosphate it is imme- 

 diate. 



The supply of organic phosphates is, however, inadequate 

 to meet the demands, and the ground mineral phosphates 

 and superphosphates are now more largely used, and they 

 have a very important place in the economical and profitable 

 use of commercial manures ; moreover, the superphosphates 

 made either from ground bone or gi'ound phosphate rock, 

 possesses an advantage for quick-gi'owing crops that cannot 

 be met by the phosphatic materials in their original condition. 

 In the process of manufacture the insoluble compounds are 

 broken up and made soluble, the phosphate not only becom- 

 ing more available, but more easily distributed in the soil. 



