SOURCES OF LIME
_Nature's Provision._ Soils are composed of pulverized stone and organic
matter. Much of the original stone contained little lime, and the human
race would become nearly helpless if there were no stores of supply in
the form of limestone, chalk, marl, etc. The day would come when the
surface soil could not produce our staple crops if its loss of lime
continued, and a means of replenishing the stock were not at hand. The
huge deposits of limestone that have not been disintegrated by processes
of weathering are assurance that the soil's need can be met forever. The
calcium and magnesium in the stone are in chemical combination with
carbonic acid forming carbonates, and there is an additional mixture of
other earthy material that was deposited by the water when the stone was
being formed, but much limestone possesses an excellent degree of
purity.
[Illustration: Lime Favors Clover at the Ohio Experiment Station]
[Illustration: Lime Affects Growth of Corn at the Ohio Experiment
Station]
_Confusion Respecting Forms._ In the public mind there is much confusion
respecting the sources and forms of lime most to be desired. Wood
ashes appealed to people, especially in an early day in our agriculture,
partly because the ashes were so universally present that tests had been
made voluntarily and otherwise in millions of instances. The value of
such tests had been obscured by the fact that the ashes contained
potash, and much of the credit of any good effect was attributed to that
fact. It has been generally known, however, that lime in peculiarly
effective form is in wood ashes, and the favor in which ashes have been
held rested not a little upon the curious preference for an organic
source of all soil amendments. This is seen in the case of direct
fertilizers.
_Dealers' Interests._ The doubts regarding the wisdom of selecting any
one form of lime for the betterment of soil conditions have been
promoted very naturally by the conflicting interests of men who would
furnish the supply. Some dealers in fresh burned lime have asserted that
it was folly to expect any appreciable result from the use of unburned
limestone. The manufacturer of ground limestone has pointed out the
possibility of injuring a soil by the use of caustic lime, and
oftentimes has so emphasized his point that farmers have become
unwilling to apply fresh or water-slaked lime to their land.
Manufacturers of hydrated lime in some instances have made a confused
situation worse by insisting upon the claim that there was a fertilizing
quality in their goods. Some dealers in lime marls have been unwilling
to have the value of their goods rated according to the content of
carbonate of lime, and have emphasized the value of fine division of the
particles and the absence of any caustic properties. The presence of
shells, evidencing an organic source of the material, has helped in the
appeal to buyers.
The rightful place of magnesia, and the possible danger of injury from
its use, have been a fruitful cause of perplexity, making price per ton
only a secondary consideration to the man wanting to supply his soil's
needs.
_Scientists' Failure to Agree._ It is only fair to say that much of the
doubt and indecision on the part of the public is directly attributable
to the conflicting statements of our scientists. It should be borne in
mind that careful investigation in respect to the relative values of
the various forms and sources of lime has been confined largely to the
short period of time that has elapsed since recognition of the lime
deficiency of our country's soils. Our agricultural literature contained
little about soil acidity 20 years ago, and our experiment station tests
afford only relatively recent results. Some knowledge of sour soils and
the efficacy of lime in their amendment is nearly as old as the history
of agriculture, it is true, but answers to the questions uppermost in
the minds of men wanting to apply lime to land have been sought only
within recent years. The variation in soil types, and in sources of
lime, and in preconceived ideas of men drawing conclusions from
incomplete data may easily account for failure of our soil scientists to
be in the close agreement in statement that would remove all confusion
in the public mind. However, the agreement respecting the facts is
becoming better assured with every added year of investigation, as a
study of station bulletins shows.