844 THE COMPLETE GRAZIER. BOOK i*v 



closely, and during the filling is well trodden. Absolute freedom from 

 mould results, because the oxygen in the air which is imprisoned is 

 converted into carbonic acid by the oxidation of a portion of the 

 carbonaceous matter present. Water joints have been used, but as the 

 water evaporates they are not so reliable as rubber joints. This is the 

 most perfect system of ensiling, but the expense of erecting such a 

 building is considered too great for ordinary practice, and it is seldom 

 adopted. Many of the so-called air-tight silos were not so in reality, 

 for, though there was no escape of air from the bottom or sides, the top 

 was rarely made absolutely air-tight. Indeed, as planking was used, 

 and as the planks seldom fitted closely, evaporation took place. This 

 want of air-tightness in the ordinary brick silo was not of great 

 importance, for it only affected the top layer, and, as will subsequently 

 be explained, some waste is almost inevitable. If an absolutely air- 

 tight covering of loose boards could be obtained, such a silo as is being 

 described would be hermetically sealed, and a perfect silo would result. 

 But this is impossible, and the advantages of a brick silo are only pro- 

 portionatety greater than those of an open-air stack. 



The expense of digging out a pit and lining it with brick, or of 

 building an above-ground silo with walls of extra thickness, has been 

 proved to be unnecessary, as instead of the walls being bulged by the 

 contents, it is almost impossible to pack the silage at the sides so closely 

 that air is excluded. This is due to the shrinkage of the material during 

 fermentation, for the mass always contracts towards the centre, thus 

 leaving a space between it and the walls. This space admits air, so 

 that a certain portion of the silage becomes mouldy, though it is less in 

 proportion in the case of chaffed silage than in that of long silage. If 

 enclosed silos are made, it is advisable to take advantage of natural or 

 artificial circumstances, whereby hollows may be utilised, as the green 

 stuff has to be lifted to a less height, and this diminishes the cost of 

 the filling. Chalk-pits and other excavations may be usefully adapted, 

 especially if on sloping ground. 



When the process of ensilage was first introduced it was thought 

 necessary to apply great weight to control the temperature of the 

 mass, and to convert the material into silage, and a weight of as much 

 as 200 Ib. per square foot was applied in many cases. It is now 

 recognised that the upper portion supplies sufficient weight to the 

 lower, and that the only part which may be wasted by insufficient 

 weighting is that immediately on the surface. The appreciation of 

 this fact has led to the adoption of totally different methods of making 

 silage, and renders open air ensiling practicable. It is especially 

 taken advantage of in making the rough and ready stack known as the 

 clamp, which is put together on the principle of the " drawn- up " 

 dung-hill. The practice of chaffing the material has some relation to 

 the principle of weighting, for the chaffed herbage packs more closely 

 at first than does the unchaffed, and less weight is required to keep it 

 near to the walls. Whilst there are these advantages in the practice 

 of chaffing, on the other hand must be considered the important fact 

 that labour is required, at the busv season of gathering in the crops, 



