LIME IN AGRICULTURE
“To be fertile a soil must contain limestone, sand, and clay, besides
the organic substances coming from humus and fertilizers. Now it may be
that nature has not endowed the soil with a sufficient quantity or with
any of these three constituents. Then the character of the soil must be
corrected by giving it what it lacks. That is what is called improving
the land. Thus a soil that is too sandy is improved by the addition of
limestone and clay; one that is too compact, too clayey, is improved by
adding sand and, still more, by adding limestone. Mineral substances
thus added to the soil to correct it are called correctives. These
substances coöperate also in the nutrition of plants, and from this
point of view may be regarded as mineral fertilizers.
“One of the most valuable of correctives is lime, which is
indispensable to soils lacking limestone, indispensable also to the
nutrition of nearly all our cultivated vegetables. It acts in various
ways. First, it energetically attacks vegetable substances, decomposing
them and converting them into humus. A pile of leaves that would take
long months to rot becomes in a short time a mass of humus when mixed
with lime. Hence its great utility in fields overgrown with weeds, and
in newly cleared land—in short, wherever there are old stumps, piles of
leaves, remnants of wood, and patches of heather, which need to be
decomposed. With the help of lime all these herbaceous or woody
substances are quickly converted into humus, with which the soil
becomes enriched to the great advantage of future crops.
“In the second place, lime corrects or neutralizes the acidity peculiar
to certain soils, as is proved by the following experiment. Let us mix
some vinegar, no matter how strong, with a little lime. In a short time
the smell and acid taste of the vinegar will have disappeared. Now
wherever masses of vegetable refuse, such as leaves, mosses, rushes,
old stumps, are undergoing decay, there are produced certain
sour-tasting substances or, in other words, acids, which are invariably
harmful to agriculture. This generation of acid occurs notably in turfy
soils, which have an excessive acidity favorable to the growth of
coarse rushes and sedges that are valueless to us, and at the same time
this acid is highly injurious to all our cultivated plants. Lime,
therefore, which is sure to correct this acidity, works wonders in
marshy lands, damp meadows, and turfy soils. We are warned of the need
of lime by the appearance of ferns, heather, sedge or reed-grass,
rushes, mosses and sphagnei.
“Thirdly, when once mixed with the soil, lime speedily resumes the form
it wore before passing through the lime-kiln; that is to say, it
becomes limestone, but in the shape of fine powder. This return to the
limestone condition is brought about by union with the carbonic acid
gas coming from the atmosphere or thrown off by the substances decaying
in the ground. Under this new form lime continues to play a useful part
by supplying the calcareous ingredient to soil that lacked it, and also
by preventing the clay from becoming too cohesive, too impervious to
air and water.
“The addition of lime to the soil should take place at the end of
summer, when the ground is dry. Little heaps of quicklime, each
containing about twenty kilograms, are placed at intervals of five
meters and covered with a few spadefuls of earth. In a short time the
moisture in the atmosphere reduces the lime to a fine powder, which is
then spread evenly with a shovel and covered with earth—an operation
involving no severe labor.
“Lime should never be applied with seed. Mere contact with it would
burn the young shoots. Neither should it be mixed with manure before it
is used, since the immediate result would be a total loss of great
quantities of ammonia, thrown off in gaseous form; and ammonia, as I
have explained, is one of the richest of fertilizers. Lime and manure,
therefore, should be used separately.
“Soils rich in turf, clay, or granite are the ones on which lime acts
most beneficially. Because of the important results attained by the use
of lime, its manufacture for purely agricultural purposes by certain
expeditious and effective methods is customary in many places. Thus in
Mayenne, where this application of lime has converted tracts of
uncultivated clayey land into rich pastures or into wheat fields of
exceptional fertility, lime is made in enormous kilns a dozen meters
high and supported by the cliff that furnishes the limestone and
sometimes the fuel also.
“All animal matter makes excellent fertilizer. Of this class are old
woolen rags, stray bits of leather, fragments of horn, dried blood from
slaughter-houses, and flesh not fit for human consumption. All these
substances are rich in nitrogen and phosphates, and if mixed with farm
manure they add greatly to its value. Lime furnishes us the means of
utilizing one of these substances, flesh, in the best way possible.
“Dead bodies of animals, heedlessly left for dogs and crows and magpies
to devour, should be cut up in pieces and then buried with a mixture of
earth and quicklime. This attacks the flesh and quickly decomposes it,
so that in a few months’ time there would be available a deposit of the
most powerful fertilizer instead of a useless, disease-breeding
carcass. As to the bones, resistant to the action of lime, they are
burned to render them more friable, and then reduced to powder. This
bone-dust, mixed with the fertilizer furnished by the decayed flesh,
will contribute to grain-field or pasture a rich supply of phosphorus.
To uses of this sort the farmer should put all horses and mules that
have had to be killed, as well as all large farm animals that have died
of disease.”