DIFFERENT METHODS OF APPLICATION. 43 



ammonia in farmyard manure is relatively so small 

 that it is scarcely possible that any could escape in 

 this way. Hellriegel's experiments have demonstrated 

 this in a very striking way. He has found that in the 

 case of a chalky soil, and during the summer and 

 autumn months, practically no loss of ammonia takes 

 place. The following considerations may be further 

 urged in support of this method of application, as 

 against immediately ploughing in the manure, viz. : 



1. That fermentation takes place more quickly. 



2. That it results in a more equable distribution of 

 the manurial constituents in the dung, by gradually 

 and thoroughly incorporating the liquid portion of the 

 manure with the soil-particles. 



Against, however, these undoubted advantages, one 

 serious disadvantage may be urged viz., that the 

 manure, before being ploughed in, becomes robbed to 

 a large extent of its soluble nitrogenous compounds, 

 which, as we have repeatedly observed, are so neces- 

 sary for fermentation ; and that, therefore, when it is 

 ploughed in, it does not so readily ferment. This 

 being so, it is highly advisable, in the case of light or 

 sandy soils, not to follow such a practice, but to plough 

 the manure directly in. 



As to the depth to which it is advisable to plough 

 the manure in, it may be here noticed that it should 

 not be too deep, so as to permit of the access of suffi- 

 cient moisture to ensure proper fermentation, and to 

 prevent rapid washing down of nitrates to the drains. 



