2o6 FARMYARD MANURE [chap. 



than fresh dung, if it has been at all properly managed. 

 We have already seen that though considerable losses 

 of nitrogen take place during the rotting down of the 

 manure, the losses of non-nitrogenous organic matter 

 are greater still, so that the manure becomes concen- 

 trated in nitrogen and still more so in phosphoric acid 

 and potash. The active compounds of nitrogen, how- 

 ever, like ammonium carbonate, grow less as the manure 

 ages, since they are constantly being converted into 

 insoluble protein-like bodies making up the bacteria 

 themselves. These of course, die and decay, giving 

 rise again to soluble nitrogenous compounds, but the 

 tendency is on the whole in the other direction, so that 

 the older the manure the poorer it becomes in ammonia 

 and kindred bodies. Hence old short dung is both 

 slower in its action and less caustic to germinating 

 seedlings or the fresh delicate rootlets of tender plants ; 

 it can in consequence be used with more safety in the 

 spring in potato drills or immediately beneath the seeds 

 of Swedes and mangolds, particularly on a light soil. A 

 few analyses of liquid manure are also given, though it 

 is subject to such variations in the amount of rain-water 

 that gets mixed with it and the degree to which its 

 constituents are held back by the litter, that little can 

 be deduced from these results as to the composition of 

 any other sample. It will be seen, however, that the 

 fertilising constituents are chiefly nitrogen and potash, 

 both in an active form ; hence it forms a very valuable 

 manure for grass land. 



Table LXII. shows a series of analyses made by B. 

 Dyer of stable manure from London, such as \s used in 

 very large quantities by farmers and market gardeners, 

 whose distance from London does not render the freight 

 too great. The most noticeable thing in the five last 

 analyses is the very low proportion of nitrogen that 



