the lime, or its crop, that exhausts the soil?

Is lime containing magnesia better than pure lime?

What is the best kind of lime?]

If lime is applied to the soil, and increases the amount of crops grown
by furnishing a larger supply of inorganic matter, of course, the
removal of inorganic substances from the soil will be more rapid than
when only a small amount of crop is grown, and the soil will be sooner
exhausted--not by the lime, but by the plants. In order to make up for
this exhaustion, it is necessary that a sufficient amount of inorganic
matter be supplied to compensate for the increased quantity taken away
by plants.

Thus we see, that it is hardly fair to accuse the _lime_ of exhausting
the soil, when it only improves its character, and increases the amount
of its yield. It is the _crop_ that takes away the fertility of the soil
(the same as would be the case if no lime were used, only faster as the
crop is larger), and in all judicious cultivation, this loss will be
fully compensated by the application of manures, thereby preventing the
exhaustion of the soil.

[Is the purchase of marl to be recommended?

How is lime prepared for use? (Note.)

Describe the burning and slaking of lime.]

_Kind of lime to be used._ The first consideration in procuring lime for
manuring land, is to select that which contains but little, if any
_magnesia_. Nearly all stone lime contains more or less of this, but
some kinds contain more than others. When magnesia is applied to the
soil, in too large quantities, it is positively injurious to plants, and
great care is necessary in making selection. As a general rule, it may
be stated, that the best plastering lime makes the best manure. Such
kinds only should be used as are known from experiment not to be
injurious.

_Shell lime_ is undoubtedly the best of all, for it contains no
magnesia, and it does contain a small quantity of _phosphate of lime_.
In the vicinity of the sea-coast, and near the lines of railroads,
oyster shells, clam shells, etc., can be cheaply procured. These may be
prepared for use in the same manner as stone lime.[AG]

_The preparation of the lime_ is done by first burning and then slaking,
or by putting it directly on the land, in an unslaked condition, after
its having been burned. Shells are sometimes _ground_, and used without
burning; this is hardly advisable, as they cannot be made so fine as by
burning and slaking. As was stated in the firs