THE DRAINAGE OF GRASS LAND 7 



when the water rises. A water-logged surface is injurious 

 to plant life not only because there is too much moisture 

 in it and too little warmth, but because neither rain nor air 

 can enter from above, nor mineral constituents be drawn from 

 below. Drainage sets all these natural forces in motion, and 

 they open the soil and disintegrate its particles for the benefit 

 of plant Ufe. 



Again, drainage is always beneficial in promoting the early 

 and late growth of grass : this alone 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 applied, the loss of fertilisers 

 by means of the drains is inappreciable when a green crop 

 is on the ground ; while water flowing from the drains under 

 a bare fallow alongside may at the same time be highly 

 charged with manurial matter. Hence the grass farmer is 

 protected, as the arable farmer cannot always be, from this 

 particular loss. The exception alluded to above is the possible 

 loss of lime — an essential constituent of plants, and one of 

 the substances most easily lost by the drains. This accounts 

 for the necessity of applying lime from time to time on 

 drained land which happens to be deficient in it. But 

 while ammonia — which, by the process known as nitrifica- 

 tion, becomes oxidised into nitric acid, and, entering into 

 combination with lime, forms nitrate of lime — may possibly 



