Liming The Land
Occasionally, when a cook puts too much vinegar in a salad, the dish
becomes so sour that it is unfit to eat. The vinegar which the cook uses
belongs to a large group of compounds known as acids. The acids are
common in nature. They have the power not only of making salads sour but
also of making land sour. Frequently land becomes so sour from acids
forming in it that it will not bear its usual crops. The acids must then
be removed or the land will become useless.
The land may be soured in several ways. Whenever a large amount of
vegetable matter decays in land, acids are formed, and at times sourness
of the soil results. Often soils sour because they are not well drained
or because, from lack of proper tillage, air cannot make its way into
the soil. Sometimes all these causes may combine to produce sourness.
Since most crops cannot thrive on very sour soil, the farmer must find
some method of making his land sweet again.
So far as we now know, liming the land is the cheapest and surest way of
overcoming the sourness. In addition to sweetening the soil by
overcoming the acids, lime aids the land in other ways: it quickens the
growth of helpful bacteria; it loosens stiff, heavy clay soils and
thereby fits them for easier tillage; it indirectly sets free the potash
and phosphoric acid so much needed by plants; and it increases the
capillarity of soils.
However, too much must not be expected of lime. Often a farmer's yield
is so increased after he has scattered lime over his fields that he
thinks that lime alone will keep his land fertile. This belief explains
the saying, "Lime enriches the father but beggars the son." The
continued use of lime without other fertilization will indeed leave poor
land for the son. Lime is just as necessary to plant growth as the
potash and nitrogen and phosphoric acid about which we hear so much, but
it cannot take the place of these plant foods. Its duty is to aid, not
to displace them.
We can tell by the taste when salads are too sour; it is more difficult
to find out whether land is sour. There are, however, some methods that
will help to determine the sourness of the soil.
In the first place, if land is unusually sour, you can determine this
fact by a simple test. Buy a pennyworth of blue litmus paper from a drug
store. Mix some of the suspected soil with a little water and bury the
litmus paper in the mixture. If the paper turns red the soil is sour.
In the second place, the leguminous crops are fond of lime. Clover and
vetch remove so much lime from the soil that they are often called lime
plants. If clover and vetch refuse to grow on land on which they
formerly flourished, it is generally, though not always, a sign that the
land needs lime.
In the third place, when water grasses and certain weeds spring up on
land, that land is usually acid, and lime will be helpful. Moreover,
fields adjoining land on which cranberries, raspberries, blackberries,
or gallberries are growing wild, may always be suspected of more or less
Four forms of lime are used on land. These, each called by different
names, are as follows:
First, quicklime, which is also called burnt lime, caustic lime,
builders' lime, rock lime, and unslaked lime.
Second, air-slaked lime, which is also known as carbonate of lime,
agricultural lime, marl, and limestone.
Third, water-slaked, or hydrated, lime.
Fourth, land plaster, or gypsum. This form of lime is known to the
chemists as sulphate of lime. Do not forget that this last form is never
to be used on sour lands. We shall therefore not consider it further.
Air-slaked lime is simply quicklime which has taken from the air a gas
called carbon dioxide. This is the same gas that you breathe out from
Water-slaked lime is quicklime to which water has been added. In other
words, both of these are merely weakened forms of quicklime. One hundred
pounds of quicklime is equal in richness to 132 pounds of water-slaked
lime and to 178 pounds of air-slaked lime. These figures should be
remembered by a farmer when he is buying lime. If he can buy a fair
grade of quicklime delivered at his railway station for $5.00 a ton, he
cannot afford to pay more than $3.75 a ton for water-slaked lime, nor
more than $2.75 for air-slaked lime of equal grade. Quicklime should
always be slaked before it is applied to the soil.
As a rule lime should be spread broadcast and then harrowed or disked
thoroughly into the soil. This is best done after the ground has been
plowed. For pastures or meadows air-slaked lime is used as a
top-dressing. When air-slaked lime is used it may be spread broadcast in
the spring; the other forms should be applied in the fall or in the