tgo FARMYARD MANURE [chap. 



ammonium carbonate disappear more quickly. What 

 the gardener calls " taking the fire " out of the manure, 

 means so reducing the free ammonia that the material 

 is no longer injurious to a plant's roots, though it still 

 remains rich in nitrogen and organic matter capable of 

 further decay. As soon as the first violent reactions are 

 over, especially after the mass has become consolidated 

 by trampling and the oxygen in the entangled air has 

 been used up, the rate of change slows down consider- 

 ably ; it now consists mainly in the attack of the 

 anaerobic organisms upon the carbohydrate material. 

 The long strawy dung begins to change to " short " or 

 rotten manure, and this change may continue slowly for 

 years, until all trace of structure is entirely gone and 

 only a brown pulp is left. During this second change 

 but little loss is experienced by the nitrogenous 

 compounds ; if the mass is kept tightly pressed and 

 moist enough to exclude air, there will be no loss 

 of fertilising constituents, only a gradual decline of 

 weight as some of the carbon compounds are con- 

 verted into gases. Of course, as the manure gets 

 older and shorter it becomes richer in nitrogen ; this 

 apparent increase is, however, simply due to the loss of 

 non-nitrogenous carbon compounds, whence it follows 

 that the nitrogen, which does not waste, always bulks 

 larger and larger in the residue. But though there is 

 no loss in nitrogen in these later stages, the more active 

 compounds, such as ammonia and the easily decom- 

 posable amides, become converted by bacterial action 

 into carbon compounds which take longer to reach the 

 plant when the manure finally gets in the soil. 



Thus, during the making and storage of farmyard 

 manure there are a large variety of bacterial actions 

 at work, some running in an opposite sense to others, 

 and it will depend on such external conditions as the 



