trenching may with equal safety be adopted. But, if the subsoil be
more or less ferruginous--if it be of that yellow unproductive clay
which in some cases extends over nearly whole counties--or of that
hard, blue, stony till which requires the aid of the mattock to
work out of the drains--or if it consist of a hard and stony,
more or less impervious bed--in all these cases the use of the
subsoil-plough is clearly indicated. In short, the young farmer can
scarcely have a safer rule than this--to subsoil his land first,
_whenever there is a doubt of the soundness of the subsoil_, or a
fear that by bringing it to the surface, the fertility of the upper
soil will be diminished. It is no reply to this safer practice to
say that even Mr. Smith recommends turning up the subsoil afterwards,
and that we have therefore a double expense to incur. For it is known,
that after a time any subsoil so treated may be turned up with safety,
and consequently there is no risk of loss by delaying this deeper
ploughing for a few years; and in regard to the question of expense,
it appears that the cost of both draining and subsoiling are
generally repayed by the first two or three crops which succeed each
improvement. What more, then, can be required? The expense is
repaid--the land is, to a certain extent, permanently improved--no
risk of loss has been incurred, and there still remains to the
improving farmer--improving his own circumstances, as well as the
quality of his land, by his prudent and skilful measures--there
still remains the deeper ploughing, by which he can gradually bring
new soil to the surface, as he sees it mellow, and become wholesome,
under the joint influences which the drain and the subsoil-plough
have brought to bear upon it.

There can, therefore, it is clear, be no universal rule for the use
of the two valuable instruments in question, as each has its own