of our land is in need of lime. Every year the soil loses lime steadily and
continuously. The rate of loss varies with the circumstances, but in
industrial areas there is a special need for lime because of the acid
ingredients in smoke and fumes from factories and business plants.
Gradual loss of lime makes the soil become acid and sour—and more
so as time goes on. Now lime is an essential plant food; unless the soil
contains it in suitable quantity, it is not possible to grow good crops.
Most cultivated crops dislike sour soil, except potatoes, which can
stand it unless it is very acid. Turnips and swedes, for instance, are both
unreliable on such soils and are less capable of withstanding drought and
pest attacks. "Finger-and-Toe" or "Club-Root" also indicates the need for
lime, as does a heavy soil that shows an excessive stickiness, a tendency to
set hard and a difficulty in getting a good tilth. But light, sandy soils
lose their lime very quickly, and it is on such soils that troubles from
sourness are most common and acute. The presence of certain weeds, such as
spurrey, sheep's sorrel and corn marigold, is one of the best indications of
a lack of lime.
Some allotment holders and gardeners have perhaps found it difficult to get
the kind of lime they need for their land. Perhaps they put in an order
months in advance of liming time and still found they could not get delivery
in time. Probably they ordered hydrated lime and would not be satisfied with
anything else. So they went without—and their crops suffered. That was a
mistake, for other kinds of lime are just as beneficial as hydrated lime; if
applied at the proper rate.
Some readers, remembering the science of their schooldays, may like
to know a bit more about "lime." The word is commonly used to mean not only
calcium oxide (quicklime), but also calcium hydroxide (slaked or hydrated
lime) and calcium carbonate (limestone and chalk). Though quicklime used to
be by far the most common form of lime bought by farmers, carbonate of lime
is gaining considerable popularity and is now as much sought after as
quicklime and its derivatives—ground and hydrated lime. Quicklime is
obtained from either chalk or limestone burnt in a lime kiln. This is
generally in lumps or it may be further processed by crushing to form ground
burnt lime, or still further by the addition of a controlled amount of water
to form calcium hydroxide (slaked or hydrated lime).