16 



the subsoil, which gradually acquires properties simi- 

 lar to the upper soil, becomes dry and porous to a 

 greater depth. Deeper ploughing, subsoiling, and 

 trenching are now practicable ; the plants have a lar- 

 ger space through which to send their fibres in search 

 of food ; the elements of a fertile soil are brought 

 into action ; and the water in passing through the 

 soil is made of great benefit, instead of doing such 

 injury by remaining stagnant. The result is, that after 

 draining, the increase of produce is often enough to 

 pay the cost of this operation in two or three years. 

 It is obvious from these facts, that the deeper the 

 drains, provided the water has a ready escape, the 

 greater the depth of soil which is made available for 

 vegetable nutrition. Experience has shown that 

 water does find a ready escape into drains four feet 

 deep, and that these are generally more beneficial 

 than those laid nearer the surface. Both the depth 

 and the distance apart must, however, be to a certain 

 extent regulated by the circumstances of the case. 



There are no strong and good soils in which the 

 water table naturally stands at a sufficient depth from 

 the surface. All such soils will be materially benefit- 

 ted by thorough draining, whatever their position 

 may be, or the inclination of their surfiice. 



Thorough drainage prevents freezing out, or that 

 process of crystallization of the surface which draws 

 young plants from their beds. 



A given quantity of manure will last longer and 

 do more service on drained than on undrained land. 



