590 THE PHILOSOPHY OF FARMING. 
consumed by man, or for his benefit, man makes 
a return to the ground in various kinds of manures. 
These spread over the surface of the soil in 
different stages of decay—have their decomposi- 
tion accelerated, both from the solution of the 
soluble portions by the rains which fall, and by 
the action of the atmosphere. The rain washes 
what it dissolves into the ground, and the air 
following the rain water as it filters off, acts also 
upon that matter within the soil, and thus carries 
food of the strongest kind to the roots of the 
plants, which are thereby restored to vigorous 
growth. So that manuresdepend upon theaccession 
of the air into the soil for their full efficiency in 
increasing growth. Manuring wet grounds is a 
waste of the greatest portion of the material, as 
it cannot promote growth, for lack of aerial matter 
around the roots of the plants within the soil. 
If thorough aeration of the soil be thus indis- 
pensable for a full growth in meadow and pasture 
grounds, according to the quality and condition 
of the soil, it is equally so in arable and ploughed 
grounds ; and as aeration is aided by pulverisation, 
the great object in ploughing ought to be to bring 
as much soil as possible into this condition. Deep 
ploughing is hence as requisite as deep draining. 
