Proceedings of the Faemers' Club. 681 



their value. The worth of any manure, artificial or otherwise, is, of 

 course, in the direct ratio of the available amounts of these substances 

 it contains. It is not enough that these should exist in the manure, 

 but they must be, as just indicated, available; in other words, they 

 must be in such condition as to be readily dissolved in the soil, so 

 that they may feed the tiny rootlets that permeate it in all directions. 

 Here lies a great diiference in artificial fertilizers, especially in these 

 valued for their phosphate acid. For instance, a bone is a phosphate, 

 and so is a chunk of ISTavassa guano ; but in* order to convert the bone 

 into a prompt manure, it is only necessary to crush it to powder, 

 while the Xavassa product, treated in the same manner, without being 

 prepared with acid, would yield only very slight results. This ques- 

 tion of the solubility of the substances does not, of course, relate to 

 ammonia, which, being a volatile gas, is liable to be discharged from 

 its combinations into the atmosphere and lost. The essential points, 

 thex'efore, in the preparation of commercial manures is to render the 

 phosphoric acid soluble, to fix the ammonia so that it shall not escape 

 from the material until applied to the earth. The first of these 

 essentials is involved in the preparation of the various kinds of super- 

 phosphates from bones and mineral phosphates. The other relates, 

 to the fabrication of poudrettes, etc., from animal offal and refuse. 



Artificial fertilizers of the character above indicated differ from 

 ordinary or barn-yard manure in their superior activity, which arises 

 from the greater ease with which the ammonia is generated and set 

 free, when the material is subjected to the action of air and moisture, 

 and from the increased solubility of the phosphoric acid, potash, etc. 

 This, as is well knovrn, explains why the eilect of an application of 

 guano, poudrette, superphosphates and manures of similar character 

 is wholly expended in orie season, while a single manuring, with the 

 less active and energetic stable refuse, will nourish half a score of crops. 

 With the superphosphates, this activity is due to the chemical treat- 

 ment which the material receives when in course of preparation, but 

 with tlie animouiated fertilizers the remote cause lies in the highly 

 organized condition of the materials from which they are derived, it 

 being a truism that the higher anv substance stands in the scale of 

 organic life, the more complex will be its constitution, and conse- 

 quently the more readilj^ will it be decomposed. The efiects' of a 

 highly organic origin in insuring the activity of a manure is seen in 

 the case of Peruvian guano, the virtues of which are due to the fish 

 which formed the food of the sea birds by which the guauo was 



