38 DUE FAEM CROPS. 



fully examine a vigorous wheat plant in a favourable soil, 

 and trace its roots downwards, we see that they ramify 

 in innumerable branches, and readily penetrate to that 

 depth, which, of course, they could not do under the ordin- 

 ary conditions of our farm ploughings. By deep cultiva- 

 tion the producing area or size of a farm may be said to be 

 increased, though the surface remains the same. Twelve 

 inches of tilled soil contain, of course, twice as much 

 mineral food as 6 inches do, and 6 inches necessarily twice 

 as much as 3 inches, which, probably, is nearer the aver- 

 age depth of our ordinary cultivation. By removing the 

 soil to this depth (12 inches) once in the course only, great 

 advantages would accrue. Air that necessary ingredient 

 of fertility in a soil would have full access to its mass; the 

 roots, extending themselves at this depth, would be under 

 more regular and favourable conditions, as regards tem- 

 perature and moisture, than when nearer the surface, and 

 the plant would, as a consequence, stand the vicissitudes 

 of weather much more securely; while the amount of 

 mineral food would be doubled, so that a largely increased 

 number of plants could be supported on the same surface- 

 area of the field, and an equivalent increase in produce 

 obtained. This doctrine or rule is applicable to all culti- 

 vated plants : with some its advantages are more percep- 

 tible than with others: no crop, however, shows them in 

 a more marked manner than the one now under con- 

 sideration. 



The chemical conditions of the soil are less understood, 

 and far less under our control, than the mechanical ; for, 

 not only is it requisite that the soil should contain all the 

 ingredients required by the growing crop, but that these 

 ingredients be severally in a state such as the plant can 

 assimilate or make use of. The roots, of course, are the 

 only parts of the plant through and by which the ingre- 

 dients of the soil can be absorbed for the use of the grow- 



