Press Bulletin No. 2. March Ist., 1901.
The Florida Agricultural
LIME AND ITS RELATION TO AGRICULTURE
-""* 3i --
IE. K. MIILLEI.
It has been known for centuries that lime, when applied to the soil. brings about
a marked transformation in it and increases its crop producing capacity,
yet this important material does not receive the recognition from
the farmers it deserves. There seems, however, a decided
tendency towards a more general use of lime by the
crop-growers of Florida, and this method is
taken to answer some of the many ques-
tions we are receiving concerning
lime and its use as a fertilizer.
FORMS IN WHICH LIME MAY BE USED.
Quick lime (Ca 0) is obtained by burning native limestone
or oyster shells. It combines with water with avidity, crum-
bles down to fine powder and forms what is known as slaked
lime. During this process it increases about one-third in
weight and about three times in volume.
Air slaked lime differs from fresh slaked lime in that it
contains a large amount of calcium carbonate. In deciding
the condition in which to purchase lime, it is well to consider
that one hundred pounds of quick lime are equivalent to about
one hundred and forty pounds of slaked lime, and one hun-
dred and seventy pounds of air slaked lime.
Floats is finely ground phosphate rock and may be used to
advantage on lands rich in organic matter. Besides furnishing
lime it also slowly furnishes phosphoric acid. If the soil is in
need of lime other forms are better for supplying the want.
Wood ashes contain from thirty to fifty per cent. of lime
and may be used with good effect. Cypress ashes may be had
for nothing in many places in the state. They contain about
fifty per cent. of lime and one-half 'per cent. of potash and
may be used to advantage.
Calcium sulphate or gysum is fund in deposits in many
parts of the country. Much of the lime in acid phosphate is
in this form.
Marl is earthy matter which contains partly decomposed
shells. Its use is limited to farms in close proximity to the
deposits since the cost of its transportation is quite high. It is
not uncommon for a marl to contain both potash and phos-
phoric acid in addition to lime.
HOW LIME ACTS.
Lime enters into the composition of all plants and is un-
doubtedly as much a plant food as potash, phosphoric acid or
nitrogen. A plant will not grow in the absence of lime, but
this substance is so widely distributed in nature that practical-
ly all land contains sufficient lime to supply the needs of the
plants that may be grown on it.
The benefit derived from an application of lime is due more
to its chemical and physical action on the soil than to merely
an increase of lime available as plant food.
Without going into detail the following are the chief chemi-
cal changes brought about through the agency of lime:
Lime as sulphate has the power to break up certain com-
pounds containing potash in an unavailable condition. It al-
so aids in the formation of double silicates of potassium and
aluminum in which form the potash though available, is pre-
vented from leaching out of the soil. It promotes a rapid de-
composition of the organic matter in the soil and causes its ni-
trogen to be converted into nitrates. This is the form in which
nitrogen is best assimilated by plants.
If there is an excess of soluble phosphoric acid in the soil,
its tendency is to combine with compounds of iron and alumi-
num and become unavailable. The presence of lime presents
this, and is even believed to be able to decompose any iron or
aluminum phosphates, which are in the soil, so that the phos-
phoric acid may be utilized ,a plant food.
Thus it appears that lime, by its peculiar chemical proper-
ties, is capable of rendering available all three of the plant
foods which may be in the soil in an inert form,
Another important function of lime is to correct the acidity
of soils which are rich in organic matter. Such soils are fre-
quently so sour that certain plants will not grow on them, yet
they produce abundant crops after an application of lime. A
moderate amount of lime also greatly facilitates tile growth of
nitrifying organisms which exist on the roots of leguminous
plants and causes the nitrogen which these little helpers secure
from the air to be converted into nitrates and in this form
stored up in the soil.
PHYSICAL ACTION OF LIME.
Aside from its chemical action, lime when applied to stiff
clay soils renders them more friable, easier to cultivate, and
better able to supply moisture, heat, and air to the plants.
Its use improves the texture of sandy soils, making them
more compact and better capable of retaining moisture and
fertilizers. It may be stated here, however, that sandy soils
will not bear very heavy applications of lime as will the heavy
WHAT SOILS NEED LIME.
From the foregoing statements it would seem that most soils
will respond favorably to an application of lime. If a soil is
decidedly acid or sour, lime may be applied with a great degree
of assurance that benefit will follow. Its application to heavy
clay soils will usually prove advantageous. The use of lime on
poor sandy soils requires caution. When added to such soils
it renders the little plant food in them available and tends to
their rapid exhaustion. It is best in such cases to add liberal
supplies of potash and phosphoric acid, and rotate the crops,
using cow peas or velvet beans to supply the nitrogen and or-
WHEN TO APPLY LIME.
In general it may be said that during the fall is the proper
time for making the application. If the land is sour, the ap-
plication may be made just previous to planting. The same
applies if only a small amount is to be used.
HOW TO APPLY.
In case quick lime is to be used, it may be placed in small
piles at convenient intervals and a gallon of water poured on
each pile. These should then be covered with earth to protect
the lime from the air. The following day the lime should be
spread as evenly as possible on the land and immediately incor-
porated in the soil with a harrow. If lumps of unslaked lime
remain, the land should be harrowed a second time after a
It is important that the lime be thoroughly mixed with the
soil and it should never be applied and turned under.
After screening the slaked lime it may be applied to advant-
age with a grain drill or a lime spreader if these implements
are at hand.
HOW MUCH TO APPLY.
This depends largely on the character of the soil and the
crops to be grown. It is considered better practice to use
small quantities and apply annually than to make heavy ap-
plications. Many, however, apply from two to five tons per
acre at intervals of from five to ten years.
Half a ton is a fair quantity for an acre of land possessing a
moderate degree of fertility.
EFFECT OF LIME ON PLANTS.
All plants are not affected alike by lime, Most of them are
benefited to a greater or less extent,some are indifferent, and a
few are injured when grown on recently limed soil. The fol-
lowing is a list of the more common plants grown in Florida
arranged in the order in which they are benefited by lime:
Lettuce, beets, sugar-cane, celery, onions, parsnips, cabbage,
cantaloupes, tobacco, egg-plants, pepper, pea, fruits, corn and
About the only plant grown in the State which is injured by
lime is the watermelon. This applies only when a moderate
quantity is used, as peas and some other legumes, corn, and
cotton are injured by large quantities of lime. It may be said
in this connection that it is better to avoid the use of lime on
soils which are to be planted in potatoes, since its use would
favor the development of the potato scab fungus.
DOES IT PAY TO LIME?
In most cases the answer is in the affirmative. A vast
amount of experimentation has been conducted in order to ans-
wer this question; in fact, nearly every Experiment Station
has done more or less work along this line, and it has been con-
clusively demonstrated that lime judiciously applied is an effi-
cient means for producing large crops at a good margin of prof-
it. It costs about the same to plant, cultivate, and harvest a
given area without regard to the size of the crop, and if this
can be doubled by the addition of a few barrels of lime to the
acre, the relative profit becomes very much greater. Besides,
the lime will manifest a good effect for a number of years. In
closing I wish to repeat that the habit of liming may become
pernicious when practiced merely for the purpose of wresting
from the soil its locked up plant food, but when practiced with
a careful system of rotation and fertilizing, it yields a profita-