use. Tests with
other carriers of potash have shown that the potash probably produced
only a small part of the effect noted, and the benefit is attributable
to the lime in the ashes which exists in an effective form. The content
of lime is variable, and largely so on account of the percentage of
moisture and dirt that may be found in most ashes, and when no analysis
has been made, the estimate of value should not be based on more than
30 to 40 per cent of carbonate of lime. The price of ashes runs so
high, as a result of prejudice in favor of this well-known kind of soil
amendment, that it rarely is advisable to buy them. Pure lime is a
cheaper means of correcting the soil acidity, and the sulphate or the
muriate of potash is by far the cheaper source of potash.

Marl.--Marls vary widely in composition. When quite pure, they contain
90 or more per cent of carbonate of lime, and have a value per ton
about equal to finely pulverized limestone, and near half the value per
ton of stone-lime. There are marls that are carriers of potash and
phosphoric acid, and are to be valued accordingly as fertilizers.

Magnesian Lime.--Some limestone is a nearly pure calcium compound, and
yields a pure lime, while much limestone contains a high percentage of
magnesia. The latter is preferred by manufacturers who furnish
pulverized lime because it does not slake readily, and is less liable
to burst the packages before required for use. A pound of magnesian
lime will correct a little more acid than a pound of pure lime, and no
preference may be shown the latter on that score. There are soils in
which the proportion of magnesia to pure lime is too great for best
results with some plants, as plant biologists assure us, but there is
too little definite information respecting these soils to justify one
in paying more for a high calcium lime than for a magnesian lime when
it is to be used on acid land. The day may come when more will be
known, but the rational selection to-day is the material that will do
the required work in the soil for the least money.

Amount per Acre.--The amount of lime that should be applied to an acre
of land depends upon the degree of its acidity, the nature of the soil,
the cheapness of the lime, and the character of the crops to be grown.
The actual requirement for the moment could be determined by a chemical
test, but the application should carry to the soil an amount in excess
of immediate requirement. When clove