SUBSOIL-PLOUGHING. 369 
growing on the edge of chalk-pits, that as the soil 
near the edge of the pit becomes thus loosened by 
the removal of the earth, that then the roots of 
the wheat -plants growing in the immediate 
neighbourhood of the pits, elongate themselves 
in a remarkable manner, some of them reaching 
to a depth of three or four feet, and this, too, 
in the same chalk, of which the superstratum is 
principally composed. In this and similar in- 
stances, the extension of the roots of the plant 
in search of nourishment is well worthy of re- 
mark, as proving the efforts which a plant thus 
situated makes to acquire nourishment, which, 
in such instances, is most likely either moisture 
or the gases of the atmosphere, since here we 
find, that the chemical composition of the sub- 
stratum is very similar to that of the surface- 
soil. The required ingredient, therefore, could 
not be chalk or silica; and it is not likely that 
alumina was needed, from the small proportion 
in which it exists in plants. Decomposing or- 
ganic matters must be nearly absent from the 
iron-bound substratum, so that atmospheric air 
and water were the only food of plants likely to 
be found by the roots of the wheat-plant in div- 
ing so deeply into the loosened chalk.—Such, I 
think, are the reasonable advantages derivable 
from the subsoiling system,—benefits which, on 
most soils, must be more or less easily within the 
reach of the cultivator. It possesses, too, the 
great advantage of improving the land from its 
own resources. No other district need be im- 
poverished, no expensive artificial fertilizers pro- 
cured, to enable the farmer to render that portion 
of his land productive, which he may have hith- 
erto neglected; he has only to avail himself of 
the advantages which the improved construction 
of agricultural machinery now offers for his ser- 
vice.” 
Three things in this long abstract from Mr. 
Johnson’s paper require to be taken with im- 
portant modifications,—first, subsoil-ploughing, 
in any case, can produce the effects he ascribes 
to it only when superinduced on efficient subsoil 
draining ; second, the permanency of its effects 
is experienced only on some lands, and either 
somewhat limitedly or scarcely at all on others ; 
and third, the beneficial effects of it, in most 
cases, do not result properly from a mere stirring 
of the subsoil, irrespective of the mixing of some 
of it with the soil, but may be realized also, and 
even combined with other advantages, by means 
of deep- ploughing and of trench - ploughing. 
These points, though with rather undue ten- 
dency to the opposite extreme, are well argued 
in the following extract of the Quarterly Jour- 
nal’s review of Mr. Shaw Lefevre’s manifesto of 
1836 :—“ Mr. Smith is naturally favourable to 
his own contrivance, of which we think he speaks 
more favourably than it deserves; and, thinking 
so, we do not admire his subsoil-plough any more 
than we would adopt his theory, or follow his 
ae geat practice of taking two white crops 
IV. 
in succession. With all his predilection for the 
subsoil-plough, had this direct question been put 
to him, If he thought it impossible to improve 
land to the highest degree of fertility without 
subsoil-ploughing ? he knows farming better than 
to have answered it in the affirmative; whereas 
had the same question been put to him in refer- 
ence to thorough draining, he would at once 
have given an affirmative answer. He therefore 
justly deprecates subsoil- ploughing as a mis- 
chievous operation, without the preparation of 
thorough draining. Thus, to the query, ‘ Have 
you used your subsoil-plough without any auxi- 
liary permanent drains?’ he answers, ‘I have, 
and it is the worst thing possible to deep-plough 
land without having it first drained; and it is 
upon that ground that in England, the shallow- 
ploughing is so much resorted to. The deeper 
stiff clay is ploughed the worse it is, because 
there is thereby a greater reservoir formed to 
hold water.’ ‘Supposing the instance of a marsh, 
where you have no fall of water, and you have 
about eight or nine inches of soil upon the sur- 
face that is marl, and underneath you come to a 
stiff substratum of clay, and it is almost impos- 
sible to get water off, the fields are separated by 
drains, and scarcely any fall for the water, would 
you then recommend your subsoil-plough ?’ ‘ Cer- 
tainly not: I think it would just make a reser- 
voir for more water to lodge.’ Again, in his 
pamphlet on thorough draining, he intimates, 
‘T have been often asked if I would recommend 
subsoil-ploughing of land which had not been | 
drained? To this I answer, certainly not; for 
until there is an escape for the water through 
the subsoil, any opening of it but provides a 
greater space for holding water, and will rather 
tend to injure than improve the soil.’ . “So 
soon as wet lands are thoroughly drained, deep- 
ploughing may follow with the greater advantage, 
but not sooner.’ Thus, having good authority for 
believing that without thorough draining, sub- 
soil- ploughing is a mischievous operation, we 
may also safely believe that with it subsoil- 
ploughing is a very innocent operation, so inno- 
cuous as to do as little good as harm. 
“he theory broached by Mr. Smith, and 
readily adopted by Mr. Shaw Lefevre, that sub- 
soil ploughed with the subsoil plough remains 
ever after friable, and is so maintained and ac- 
celerated by the action of the water and the ac- 
tion of the atmosphere, which is constantly going 
like a tide into and out of the soil, admits of 
doubtful acceptance from its improbability. It 
is a well ascertained physical fact, that water 
percolating through any state of soil has a ten- 
dency to consolidate it, and especially it will 
most easily consolidate friable soil. Pour water 
upon loose sand, and observe how firm the sand 
immediately becomes. Observe how easily a fine 
barley-seed furrow is consolidated by a shower 
Perceive how firm the soil becomes 
These being natural effects 
2A 
of rain. 
over a deep drain. 
