On the Maintenance of Fertility in new Arable Land. 201 
potatoes. The mineral portion of all this matter is annually 
taken out of the soil. In the sales of vegetable produce alone, 
it thus sustains an annual loss of about 4 tons of its most va- 
luable portion. But this is partly compensated by the purchased 
cattle-food which is consumed upon it: — About 200 quarters of 
oats, 10 to 20 tons of oil-cake, and 40 to 50 quarters of linseed, 
barley, and beans are thus consumed. The weight of their mineral 
constituents may be about 35 cwt. This reduces the amount 
of robbery committed, to 2^ tons ; and we must suppose that the 
land is annually suffering an abstraction of this quantity of its 
best part, not to speak of the mineral portion of about 40 tons of 
butcher's meat also taken out of it. And all this, and more — 
for the land, so far from suffering from the treatment it receives, 
is exhibiting every year greater ability to grow the heavy and 
bulky crops it has hitherto yielded — all this and more must be 
manufactured and prepared as vegetable food, by the agency of 
the air and rain, out of the very substance of the land. 
" But this obviously cannot last for ever — the land must 
ultimately be exhausted :" — So he will say who has not duly 
considered the origin of the soil and the means by which it is 
maintained. The mineral part of the soil is obviously the result 
of the disintegrati(;n of rock ; and in the subsoil below it an end- 
less store of similar matters exists. We may see here the great 
advantage of any system bv which the rain-water shall be enabled 
and induced to sink through the land down to the subsoil below it, 
there to effect the solution of those substances occurring there, 
which in their present state are useless to plants. And probably 
one great cause of the barrenness of undramed land is to be found 
in the circumstance that its crops, after using up the limited stores 
of food which it contains, are afterwards dependent upon the very 
small portion which the rain-water, under the unfavourable cir- 
cumstances in which it is there placed, can provide for them. 
Undrained lands send the water off their surface ; they do not 
permit it to penetrate, and thus it has no chance of performing 
that which may be called its appointed office — no chance of pre- 
paring from the substance of the soil a sufficient supply of nutri- 
ment for the plants growing on it. 
The third point referred to above is also a most important one 
in the general scheme of permanent arable culture. It will be 
seen that, as it is, under our plan of cultivation (and the same 
will be found to a greater or less extent under every other plan 
in operation), a large draught is annually made upon the sub- 
stance of the soil, in order to maintain its fertility; and it is not 
desirable unnecessarily to increase this call by carelessness in 
using the means we have of supplying the wants of the crops. 
The management of manure is obviously a most important branch 
