12 PERMANENT AND TEMPORARY PASTURES 



of the soil, as it would be in an undrained state. Thus, in 

 well-drained land, the air is being continually carried into the 

 soil by rain, and forced into it by atmospheric pressure as the 

 subsoil water falls to a lower level, whilst the air is expelled 

 when the water rises. A water-logged surface is not only 

 injurious to plant life 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 the plant life upon it. 



Again, drainage is always beneficial in promoting the early 

 and late growth of grass, and this is of enormous value in feed- 

 ing 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. A^oelcker 

 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. On the contrary, 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 con- 

 stituent of plants, and one of the substances most easily lost 



