The Dorset County Express and Agricultural Gazette.
Dorchester, Dorset, England, 1860-01-24 00:00:00

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ALTERNATION OF CROPS.

(From the Gardeners' CAraniele and Agricaddtral
Gazdte.)

An opinion is very prevalent, founded apparently
upon long-bought experience, that two crops succes-
sively of the same plant on the same ground will not
succeed. An apple or plum tree, for instance, it is
said, will not thrive where an apple or plum tree has
grown and died before • wheat will not give a good
return where wheat ha; been the previous year ; sugar
-
beet is sure to be decayed under like cirmunatances, or
clover is sure to be sick if grown more frequently
than once in eight years.
Now, true as the facts asserted may be in genersl,
there is probably some fallacy in the notion that the
reason which is at the bottom of them all is that the
soil has become tired and reunites rest. The apple and
plum tree will do well enough if care be taken that no
out roots remain in the ground ; wheat has been grown
with good results under -pale liu•dlandry for many
years in aucceeion ; sugar-beet it iii well-known is
oontanaivated the second year from the putrescent re-
mains of the old taproot ; and it is not at all certain
that clover sickness is attributed to the right cause.
Now as clover is naually sown with barley after a
arop al asseepselsorleeref el -which are always buried
by the plough, it is not mpossible that occasionally.
though not always, the plant may be impaired in con-
stitution in an early stage of growth front this cause,
though the evil is not apparent in general, or at least
is not °Weaved till the following year. We have ex-
amined the root' of pick clover repeatedly without ever
finding any unhealthy appearance about them, or the
slightest trace of any fungus spawn which might affect
them. It is the part above the ground which is the
seat of disease. The leaves lose their healthy green,
and ultimately the base of the stein, or what is often
called the crown of the root, decays, and the whole
plant falls a sacrifios. Minute fungi may exist upon the
leaves, but if so they are in no respect the came of the
evil. It in indeed possible that in some instances there
may have been some original constitutional defect which
was inherent in the seed; but such defects usually show
themselves at an early stsge of growth, and we are far
more inclined to attribute the condition of the plant in
the majority of instances to infection from decaying
matter than from the cause just mentioned. The notion
is at any rate worth a thought, especially as it seems
quite preposterous to believe that clover will not so
succeed, but the point is to discover the real cause why
it will not, supposing the assumption to be grounded
in fact.

Whatever may be th:.ught of the notion just put for-
ward as to the origin of clover sickness, we would
strongly recommend no one to attempt to sow clover
seed where a large portion of the crop has failed, for
the produce is almost sure to be diseased. In the case
of oats we have proved by consecutive experiments
that seed from diseased plants will produce • diseased
offspring, and we do not doubt that even where the
original coupe of disease may not exist, it may be pro•
pagated by seed, en evil which no one con guard
against till measures be taken by agriculturists to ensure
• supply of seed of every kind from healthy sources.
More we are convinced depends upon this than is gene-
rally imagined.
Let us however pass on to another case, which was
mentioned above.

It is acknowledged almost universally that in the
common system of cultivation wheat cannot profitably
succeed wheat. The second crop is weak and patchy,
and for the must part a failure. The mule may be
rimmed, from common consent, respecting wheat after
Italian rye-grass mixed with clover. In this case,
though the crop in parts may he good, after • time
patches become blighted, and die. Now here, again,
we have taken pains to ascertain the CRUM!. We do
not assert we have satisfactorily traced tide to spawn
arising from decaying vegetable matter attacking the
roots. Wo know, however, so far as our own expe-
rience goes, that if the blighted straws are split up
there will very generally be found traces of fungous
matter. We would auggest then that it is very pos-
sible that where wheat succeeds wheat the strong
stubble of the wheat crop which is ploughed in may
generate spawn, perhaps no delicate as to escape notice
when the evil is done, and that this, coming here and
there in contact with the young roots. may induce
disease; and no where Italian rye-grass is mixed with
clover, the bard wiry remains of the base of the stem
may in the same manner have an evil influence upon
the wheat. We do not assert that this is the case,
but we think that the suggestion is worth some °beer-
elation and experiment. That the cause is capable of
producing the effect is from analogy beyont doubt. It
doers not follow that because decaying clover routs afford
a wholesome note set to young wheat that the rye-
grass or old wheat 'dabble may do the mashie, though,
according to theory, so far as they go, they will at least
restore to the ground a part of the waste.
We are, however, quite of Mr. Nesbit's opinion, that
vital processes are not to be judged of entirely by elm-
miatry. If the analysis of plants alone could tell us
precisely what has been withdrawn by a given crop from
the soil, and what must be restored to insure
agriculture would become in • great measure& matter of
certainty instead of being subject to a thousand acci-
dents as it is. That the farmer may and does derive
great advantage from his own chemical knowledge or
that of others it would be folly to deny, but he must
not suppose that all begins and ends there. There are
mysteries which are far beyond the reach of the highest
human knowledge; but the veil is sometimes capable
of being withdrawn, yet only where people do not relit
satialled with • forgone conclu.don, but are content to
keep their minds open to fresh suggestion., without in.
dolently making up their bundle of faggots, end wrap
ping themselves up in their own prejudices.—M. J. B.