field of usefulness
is broad in that it is an essential plant food and provides the active
means of keeping the feeding ground of plants in sanitary condition. We
want to know how it comes about that our soils are deficient in lime,
and how we may determine the fact that they are deficient. We wish to
know the relative values of the various forms of lime and how we may
choose in the interest of our soil and our pocketbook. The time and
method of application are important considerations to us. There are
many details of knowledge, it is true, and yet all fit into a rational
scheme that shows itself to be simple enough when the facts arrange
themselves in an orderly way in our minds.

Lime cannot take the place of nitrogen, nor phosphorus, nor any other of
the essential plant foods. It is not a substitute for any other
essential factor in plant growth. It would be folly to try to depend
upon lime as a sole source of soil fertility. On the other hand, we have
learned very definitely within the last quarter of a century that it is
foolish to depend upon commercial fertilizers and tillage and good seeds
for full production of most crops from great areas of our farming
country that have a marked lime deficiency. The obvious need of our
soils is the rich organic matter that clover and grass sods could
furnish, and their fundamental need is lime. Most farms cannot possibly
make full returns to their owners until the land's hunger for lime has
been met. The only question is that regarding the best way of meeting
it.

CHAPTER II

THE LIME IN SOILS

_Limestone Land._ Soil analyses are serviceable only within certain
limits, and in the case of the normal soils that comprise the very great
part of the entire humid region of the United States the practical man
gives little heed to what special analyses might show him when deciding
upon the purchase of a farm. He does know, however, that a limestone
soil has great natural strength, and recovers from mistreatment more
readily than land low in lime. It has staying powers, and is dependable,
unless through natural processes the lime leaches out or loses
availability. All limestone areas have gained reputation for themselves
as producers of grain and grass.

_Other Calcareous Soils._ It is not only the limestone areas that stand
high in esteem. There are types of soil with every varying percentage of
lime down to clear sand or to peat, and some of the types are finely
calcar