t 12 per cent of potash, and the muriate and the sulphate--both
salts, in a more or less pure form, being used. A word or two may be
added on the effect of the two forms of potash--viz., as the sulphate
and as the muriate.

_Relative Merits of Sulphate and Muriate of Potash._

It is a well-known fact that muriate of potash, far from having a
beneficial effect on certain crops, is actually harmful. Of these,
sugar-beets, potatoes, and tobacco may be mentioned. In the case of
beets it seems to have an effect in lessening the percentage of
crystallisable sugar, while potatoes are rendered waxy. With regard to
the tobacco-plant, it seems to impair the value of the leaf from the
smoker's point of view. That this deleterious action is due to the form
in which the potash is present, and not to the potash itself, seems to
be pretty clear, since potash in the form of sulphate has not this
deleterious effect on these plants. Another objection which has been
urged against muriate of potash is that, when applied as a manure, it
is apt to give rise to the formation of calcium chloride,--a compound
which is distinctly hurtful to many plants. A similar charge cannot be
brought against sulphate of potash, since gypsum, which is the chief
compound it is likely to give rise to, is of much value, as we have
already pointed out, as an indirect manure. On the whole, therefore,
sulphate of potash seems to be the safest form in which to add potash.
Unfortunately, however, most of the commercial sulphates are very
impure, and contain generally considerable quantities of muriate. In
favour of the muriate, it may be said that it is the more concentrated
manure, and that it diffuses better in the soil than the sulphate--a
point of great importance. It has, moreover, been used without any bad
effect for clover, corn, grass, and some root crops.

_Application of Potash Manures._

The extreme tenacity with which the soil-particles fix potash salts,
when applied as manures, is a point which ought to be borne in mind in
their application. This, as we have just noticed, is greater in the case
of the sulphate than in the case of muriate, and it has been observed
that certain other fertilisers seem to exercise a considerable influence
in hindering their fixation. Among these may be mentioned bone-meal and
farmyard manure. Nitrate of soda also seems to increase the
diffusibility of potash salts. Conversely, potash salts seem to help to
fix ammonia