= 
colation of water, but not faster than the water 
may have time to deposit the iron. Hence the 
pan or crust is only found on subsoils of clay 
having gravel embedded in them. It is quite 
obvious from the nature of the deposition, that 
were there quick absorption of the water, or, in 
other words, were the subsoil thorough drained, 
there would be no deposition of pan. The iron 
in the pan is in a state of hydrate, is soluble, 
and of course injurious to vegetation; but when 
this hydrate becomes dry, by exposure to the 
action of the air, it is converted into a pure 
oxide, which is insoluble, therefore innocuous to 
vegetation, and which generally mixes with, and 
forms a component part and colouring matter of, 
the soil. The most rational method, therefore, 
of getting quit of pan is to render the soil 
thoroughly dry ; and any other method is only a 
temporary expedient. But after all, the extent 
of peculiar subsoil which can generate pan 
must be comparatively small, and is chiefly to 
be met with under peaty earth in moorland 
_ districts. 
“Tt is desirable that farmers, particularly small 
farmers, should incur no more expense in the 
purchase of implements than what is absolutely 
necessary for the right management of their 
farms. But, independently of this circumstance, 
many small farmers have not two pairs of horses 
of sufficient strength to work a subsoil-plough. 
We know those who have tried it and could not 
succeed to work it with fewer than three pairs 
of horses. It is said that the Muirkirk subsoil- 
plough is more easily worked than Mr. Smith’s; 
but whether it does its work better or not, which 
is the chief criterion of excellence, we do not pre- 
tend to decide. There is another consideration 
which is not unworthy of notice, in reference to 
any extraordinarily heavy work to be performed on 
afarm. We may propound it asan axiom in horse 
labour, that every kind of work which requires 
more than the combined efforts of two horses to 
execute, is injurious to the horses themselves. 
When more are yoked together, there is so much 
counteraction in performing work, that the weak 
and sanguine tempered horse is always in the 
end sure to suffer. By using the four-horse 
plough much in bringing in land, trench-plough- 
ing, splitting down old dykes of turf, and tearing 
up old decayed tree roots, two very powerful 
horses of our own, both of sanguine tempera- 
ment, suffered so severely as to superinduce in- 
flammation in the lungs that terminated in help- 
less broken wind, and so became unfit for or- 
dinary farm work. We afterwards tried to exe- 
cute much of the roughest part of that kind of 
work by trenching with the spade, and found it 
much more cheaply done, taking into account 
its at once finished effectiveness. Deep-plough- 
ing cannot, of course, be executed, in present 
circumstances, otherwise than with horses; but 
it is the easiest kind of hard labour they under- 
take; and two strong horses will turn over a 
ebbing lide el Ow a es 
ee 
SUBSOIL-PLOUGHING. 
deep furrow of thorough drained land, and four 
horses a furrow of sufficient depth for every pur- 
pose of culture.” 
Subsoil-ploughing, whether judged by theory 
or by the many appeals to experiment which 
have been reported in the agricultural periodi- 
cals, is least suitable in very light lands, as it 
tends to make them too loose,—and in very 
strong plastic clay subsoils, as they immediately 
or speedily run together again; and most suita- 
ble in lands with a strong moorband pan between 
an open soil and a porous subsoil, as it instantly 
breaks up the pan, and renders the whole mass 
of earth permanently absorbent,—and in a sub- 
soil of marly clay or in one of mixed rubble and 
clay, as it produces a permanent openness and 
porosity,—and in half open or lazily absorbent 
lands of all kinds in very rainy districts, as it 
permanently increases their capacity of letting 
surface water rapidly down to the drains. But 
in some cases in which proper subsoil-plough- 
ing is useless, trench-ploughing may be benefi- 
cial ; while in most cases in which it is eminently 
useful, trench-ploughing may be equally or supe- 
riorly beneficial. Mr. Stephens, in his Book of 
the Farm, makes this out so well by a combined 
appeal to principle and report and experiment, 
that we cannot better state the comparative 
claims of subsoil-ploughing and trench-plough- 
ing than by making ourselves debtors to him for 
the passage: —“ There is a mode of trenching 
ground,” says he, “ which is best done with the 
plough, its object being to imitate the work of 
the spade by descending deeper than the ordinary 
depth of furrow, and of commixing part of the 
subsoil with the surface soil, which has been pro- 
bably rendered effete by overcropping. Ground 
can be trenched with the plough in two ways, 
either with a large sized common plough drawn 
by 4 horses, or with one plough going before and 
turning over an ordinary furrow-slice, and another 
following in the same furrow drawn by 2 or more, 
usually with 3 horses, or both ploughs drawn by 3 
horses each. It is best performed across the ridges. 
In either of the above ways the same effect is 
produced in similar soil, breaking up indurated 
gravel, deepening thin clays, ameliorating stiff 
clays by exposure to the air, and mixing old and 
new soils together, the ultimate effect on all 
being to deepen that portion of the soil which 
is used by the cultivated crops. In one respect 
trenching has the same effect as subsoil plough- 
ing, namely, the stirring of the ground to the 
same depth, the first plough turning over a fur- 
row of 7 inches in depth, and the second going 
8 or 9 inches deeper, making in all a furrow of 
15 or 16 inches in depth ; but in another respect 
the two operations leave the soil in very different 
states—the subsoil plough stirs the soil to the 
depth named, but brings none of it to the sur- 
face, whilst the trench-plough does not altogether 
bring that which was undermost to the surface, 
but commixes the under and upper soils together. 
