Nashville union and dispatch. [volume] (Nashville, Tenn.) 1866-1868, 1867-08-22
Rotation Of Crops.

The practical good of the rotation OF
crops is well known, but the philosopkic
reasons, though much written about,
have not yet been fully and satisfactorily
explained. One Of our exchanges has
the following on this important subject
There are two theories. The fra or er-
cTetoyy theory accounts for the phenomena
thus: One crop does better where il fol-
lows another, because every plant leaves IN
the soil certain exCretary matters that are
not friendly to other plants Of its own spe-
cies, while they are appropriate food for
different plants. Plants seem endowed
with something Of the same instinct as ami
mails, and avoid their own feces, or the
dead matter thrown from their own bark
and roots. Until these are -decomposed
and removed from the earth by other
plants, or by gradual effects of decomposi-
ton. the same crop cannot be advantage.
ously planted in the same soil. Hence, in
raising dubious flowers like the hyacinth,
which grows in water, there must be a
frequent change Of the water, in order to
remove the excretory matter thrown of
from the roots Of the plant. The same
foul water, however, is found TO be coed
stimulsnt TO other kinds of plants, and
will sometimes make them flourish better
than pure water. II is also well known
fact that nurserymen find it difficult to
make second crop of young apple trees
grew where they have been grown before
Even with heavy manuring they find il
better policy TO take piece Of ground that
has been occupied by some other crop. II
there are exceptions TO the advantages of
rotation, a. there seems 70 be in the case of
the onion and some other garden crops. IL
is in case Of gross feeders, where great
deal Of manure is used, which, by its fer
meutation in the soil decomposes the ex-
cretory matter Of The crops of the prece,
ding season. The onion crop is almost al
vraxs heavily MANFRED and dressed with
asbea which furnish lime and potash. two
powerful alzalies, that act with great rapid
itv upon all vegetable fiber. So much for
this theory.
The second theory may be stated thus !;
Each plant absorbs some essential constitu-
ent from the soil, which, in time become
exhausted. II, for instance, the wheat plant
demand phosphate Of lime, and there IS
but small quantity In the SOIL, a ialls te
be perfectly developed when Il cannot ma
a full supply Of this mineral. 1t must De
restored by the application Of manure or
by faliow, or the growth Of some other
crop that does not require much phosphate
Of lime for its perfect development.
Another example is frequently given OF
root crops, which usually contain consider
able quantities Of alkalies. This theory
supposes a root crop to exhaust the ready
formed alkalies in the soil, and that aka
line manures must be added or change Of
crops be made, while further disintegra-
ton OF the soil IS setting at liberty new
supplies Of slkalies. We think there Is
much truth in both az the theories AZ above
stated, bat thai neither Of them. and espe-
cially not the second one, win fully account
for the advantages Of rotation. Ii Is
probably the exhaustion Of the organic or
vegetable matters in the soil, more by one
crop than another, that chiefly has 70 do