ld be made with samples of soil from various parts of the field,
and they should be taken beneath the surface. One just criticism of
this test is that while no acidity may be shown, the lime content may
be too low for safety.

[Illustration: Red clover on limed and unlimed land.]

A Practical Test.--The importance of alkalinity in soils is so great,
and the prevalence of acidity has such wide-spread influence to-day,
limiting the value of the clovers on a majority of our farms, that a
simple and more convincing test is suggested here. Every owner of land
that is not satisfactorily productive may learn the state of his soil
respecting lime requirement at small expense. When a field is being
prepared for seeding to the grain crop with which clover will be sown,
a plat containing four square rods should be measured off, and
preferably this should be away from the border to insure even soil
conditions. A bushel of lump-lime, weighing eighty pounds, should be
slaked and evenly distributed over the surface of the plat of ground.
It can be broadcasted by hand if a spreader is not available, and mixed
with the surface soil while in a powdered state. The plat of ground
should be left as firm as the remainder of the field, so that all
conditions may be even for the test. The appearance of the clover the
following year will determine whether lime was needed or not. There is
no reason why any one should remain in doubt regarding the lime
requirement of his fields. If income is limited by such a cause, the
fact should be known as soon as possible.

Duration of Effect.--Soil acidity is not permanently corrected by a
lime application. The original supply failed to prove lasting, and the
relatively small amount given the land in an application will become
exhausted. The duration depends upon the degree of acidity, the nature
of the soil and its crops, and the size of the application. Experiments
at the Pennsylvania experiment station have shown that an application
only in sufficient amount to correct the existing acidity at the time
of application will not maintain an alkaline condition in the soil,
even for a few months. There must be some excess at hand to unite with
acids as formed later in the crop-rotation, or limings must be given at
short intervals of time to maintain alkaline conditions.

Experience causes us to assume that enough lime should be applied at
one time to meet all requirements for a single crop-rotation of four,