ellent manure,
and may be applied in almost unlimited quantities, _while the plants are
growing_, if used after they have gone to top, it is injurious. Salt has
been applied to asparagus beds in such quantities as to completely cover
them, and with apparent benefit to the plants. Of course large doses of
salt kill all weeds, and thus save labor and the injury to the asparagus
roots, which would result from their removal by hoeing. Salt may be used
advantageously in any of the foregoing manners, but should always be
applied with care. For ordinary farm purposes, it is undoubtedly most
profitable to use the salt with lime, and make it perform the double
duty of assisting in the decomposition of vegetable matter, and
fertilizing the soil.

Soda unites with the silica in the soil, and forms the valuable
_silicate of soda_.

_Nitrate of soda_, or cubical nitre, which is found in South America,
consists of soda and nitric acid. It furnishes both soda and nitrogen to
plants, and is an excellent manure.

LIME.

The subject of _lime_ is one of most vital importance to the farmer;
indeed, so varied are its modes of action and its effects, that some
writers have given it credit for every thing good in the way of farming,
and have gone so far as to say that _all_ permanent improvement of
agriculture must depend on the use of lime. Although this is far in
excess of the truth (as lime cannot plow, nor drain, nor supply any
thing but _lime_ to the soil), its many beneficial effects demand for it
the closest attention.

[Do all soils contain enough lime for the use of plants?

What amount is needed for this purpose?

What is its first-named effect on the soil?

Its second? Third? Fourth? Fifth?

How are acids produced in the soil?]

As food for plants, lime is of considerable importance. All plants
contain lime--some of them in large quantities. It is an important
constituent of straw, meadow hay, leaves of fruit trees, peas, beans,
and turnips. It constitutes more than one third of the ash of red
clover. Many soils contain lime enough for the use of plants, in others
it is deficient, and must be supplied artificially before they can
produce good crops of those plants of which lime is an important
ingredient. The only way in which the exact quantity of lime in the soil
can be ascertained is by chemical analysis. However, the amount required
for the mere feeding plants is not large, (much less than one per
cent.), but li