THE PHILOSOPHY OF FARMING. 591 
No crop can be thoroughly good without it; yet 
we see furrows cut only a few inches deep, and 
nothing but sward turned up to be pulverized; 
the most friable portion of the soil being left 
untouched, and therefore comparatively inert. I 
have seen good crops obtained from exhausted 
ground simply by deep ploughing, though such 
treatment ultimately ended in exhausting the soil 
still more, through want of a due return in manure 
to the soil. And not only is deep ploughing the 
foundation of good crops, but it ought to be 
followed out with complete harrowings and 
breaking up of clods, and division of the particles 
of the soil. Such a method allows a freer acces- 
sion of air, and distributes throughout the soil a 
larger portion, encouraging thence a greater 
extension of roots and more successful action. 
And herein lies the secret of the great success 
of subsoil ploughing and the subsoil trenching of 
spade husbandry. Aeration is thereby increased, 
and the plants grown are afforded more ample 
space for the extension of their roots, and come 
in contact with an extraordinary quantity of 
alimentary particles. Nor is this beneficial effect 
of subsoil culture confined to one crop, but con- 
tinues until the filtration of particles of soil from 
