MANURE. 139 



192. It is perfectly evident, from this view, that the main 

 agricultural value depends on the ammonia or nitrogen, and 

 the geine. The lime, in its forms of salts, goes but little 

 way towards this value, yet valuable, so far as they exist. 

 It is evident, from section 74, that the lime in the above 

 salts of lime, the annual product of one cow, is sufficient to 

 supply the grain and straw of a crop of 140 bushels of rye. 



193. If these, then, are the elements of plants which are 

 found in cow-dung, is it to the organic or the inorganic 

 portion that the enriching power is due? The great value 

 of dung as a manure, has been supposed to be due to its 

 animal matter. I'he common idea of animal matter in- 

 includes substances which contain much nitrogen, but is it to 

 the nitrogen, or to salts, that the chief value of manure is 

 duel To the nitrogen, chiefest and first, and that, too, as it 

 exists in the albuminous portion of dung. The nitrogen of 

 the hay contributes very little to the value of manure. The 

 hay furnishes the geine. That it is the nitrogen of dung only, 

 the part not contained in the hay, which evolves ammonia, 

 is evident ; for if the nitrogen of the hay only, was the essen- 

 tial element of dung, then hay, which contains about one per 

 cent, of nitrogen, could supply its place : 50 pounds would be 

 equal to 100 pounds of dung. It is well known that such 

 effect is never produced by planting on hay. 



194. It is not to the nitrogen only, in dung, to which can 

 be referred the action of this manure. It depends on its 

 other elements, salts and geine. The action of nitrogen is 

 referred to its power of forming ammonia, and this then 

 acts in two ways. First, upon geine, or the hay part; 

 secondly, upon silicates. First, it is a powerful alkali. Now 

 it has been shown that all alkaline earths convert insoluble 

 into soluble geine. Secondly, it is a well-established fact, 

 that the production of nitre is not necessarily dependent on 



