12 FARMYARD MANURE. 



in rotten dung is richer in nitrogen than an equal quantity of in- 

 soluble organic matter from fresh dung. Thus 76 per cent, of 

 insoluble organic matter of fresh dung contain 1*46 per cent, 

 whilst 52 per cent, of it from rotten dung very nearly contain the 

 same quantity, namely, 1'26. Or, 



100 parts of insoluble organic matter ) -, . Q9 f . , 



from fresh dung contain . . _ . . . . } l 92 P er cent ' of mtr g en - 



100 parts of insoluble organic matter ) ,, 



from rotten dung contain ..... J *" " " 



5. On the other hand, the relative proportion of insoluble 

 inorganic matter increases much during the fermentation of the 

 dung, since dry fresh dung contains about 12 per cent, of 

 insoluble mineral matters, and dry well-rotten dungs 26'8 per 

 cent, or more than double the amount which is found in fresh 

 dung. 



6. But perhaps the most striking difference in the compo- 

 sition of fresh and rotten dung is exhibited in the relative pro- 

 portions of soluble organic matter. Well-rotten dung, it will be 

 observed, contains rather more than twice as much soluble 

 organic matters as the fresh ; with this increase the amount of 

 nitrogen present in a soluble state rises from *44 per cent, to 

 1*21 per cent. 



7. Not only does the absolute amount of soluble nitrogenised 

 matters increase during the fermentation of dung, but the soluble 

 organic matters relatively get richer in nitrogen also. Thus, 



100 parts of dry organic soluble matter) g-o 

 from rotten dung contain ...... / 



8. Lastly, it will be seen that the proportion of soluble mineral 

 matters in rotten dung is more considerable than in fresh. 



9. On the whole, weight for weight, well-rotten farmyard 

 manure is richer in soluble fertilizing constituents than fresh 

 dung, and contains especially more readily available nitrogen, 

 and therefore produces a more immediate and powerful effect on 

 vegetation. 



Bearing in mind the differences observable in the composition 

 of fresh and rotten dung, we can in a general manner trace the 

 changes which take place in the fermentation of dung. Farm- 

 yard manure, like most organic matters, or mixtures in which the 

 latter enter largely, is subject to the process of spontaneous 

 decomposition, which generally is called fermentation, but more 

 appropriately putrefaction. The nature of this process consists 

 in the gradual alteration of the original organic matters, and in 

 the formation of new chemical compounds. All organic matters, 

 separated from the living organism, are affected by putrefaction, 



