ON 



FARMYARD MANURE, 



IT is a prevailing opinion amongst farmers that the peculiar 

 smell which emanates from dung-heaps is caused by the escape 

 of ammonia, and that the deterioration of farmyard manure 

 is due, in a great measure, to the loss of this most fertilizing 

 substance? which is incurred by careless management of dung- 

 heaps. In a paper published in the volume for 1856 of 

 the Journal of the Royal Agricultural Society, however, I 

 showed that the proportion of free ammonia, or rather vola- 

 tile carbonate of ammonia for it is in this form that ammonia 

 makes its appearance in putrefying organic matters is so 

 inconsiderable in fresh as well as in fermented dung in all 

 stages of decomposition, that it is not worthy to be noticed 

 in a practical point of view. This being the case, it is evi- 

 dent that the escape of ammonia cannot be the cause of ma- 

 nure-heaps losing much in fertilizing property even when 

 freely exposed to the atmosphere for a considerable length of 

 time. Consequently the chemical means which have been 

 suggested from time to time for preventing the loss of ammonia 

 in dung-heaps may be altogether dispensed with. As there 

 is, practically speaking, no free ammonia in either fresh or 

 rotten dung to be fixed, the addition of dilute sulphuric acid, a 

 solution of green vitriol, and other chemical agents which change 

 volatile compounds of ammonia into non-volatile combinations, is 

 unnecessary and useless. At any rate, these and other fixers of 

 ammonia are useful additions to dung-heaps only in so far as 

 they themselves possess fertilizing properties. In the paper to 

 which reference has been made, I furnished experimentally the 

 proof that, simultaneously with the formation of ammonia which 

 always proceeds when organic substances containing nitrogen 



B2 



