THE DEAINAGE OP GEABS LAND. 11 



all these natural forces in motion, and they open the soil and 

 disintegrate its particles for the benefit of the plant-hfe upon it. 



Again, drainage is always beneficial in promoting the early 

 and late growth of grass, and this is of enormous value in feeding 

 stock. The early autumn and late spring frosts do not arrest 

 growth on drained land so quickly as on that which is sodden 

 with moisture. And on the latter there is also the additional 

 injury which the hoofs of cattle inflict on the grasses. 



Thus one of the effects of drainage is to produce an ever- 

 growing crop. It has been urged with perfect truth that from 

 arable land manures are often washed into drains, especially in 

 wet seasons, and that in draining, a farmer may be providing an 

 outlet for manure which he has placed on the surface at great 

 expense. Experiments by the late Dr. Voelcker and others have 

 clearly proved that, with one exception for which the remedy is 

 easily apphed, the loss of fertilisers by means of the drains is 

 practically nil when a green crop is on the ground. On the 

 contrary, water flowing from the drains under a bare fallow 

 alongside, was at the same time highly charged with manurial 

 matter. Hence the grass farmer is protected from this particular 

 loss as the arable farmer cannot always be. The exception 

 alluded to is the possible loss of hme. This essential constituent 

 of plant-life is one of the substances most easily lost by the drains, 

 and it accounts for the necessity of applying this mineral from 

 time to time on drained land which happens to be deficient in 

 it. But while ammonia — which becomes oxidised into nitric 

 acid, and, entering into combination with lime, forms nitrate 

 of lime — may possibly be wasted, it is satisfactory to remember 

 that superphosphate of lime and other forms of phosphoric acid 

 are never thus lost. Nor does it appear that potash is easily 

 abstracted, so that there need be no hesitation in applying these 

 substances from fear that they will be carried away by the drains. 



It may be accepted as a general truth that grass land should 

 not be drained so deeply as arable land. The weight of engines 

 and heavy agricultural machinery has not to be allowed for, and 



