, 1908-06-17

foods. Large quantities of it are required
by all crops. A considerable part of the ash
of most plants consists of this material, and
though closely related to sodium in it's chsmi-
cal properties, the latter cannot replace it in
the plant. Plants growing in soil which
Contains more sodium than potassium. will
nevertheless absorb much more of the
potash. One of the first signs of a lack of
potash is q decided cessation in growth with.
out other apparent cause of trouble. The
plants often have tn Dir normal green COLOUR
but make very little starch or sugar, aud
almost no protein or nitrogeno IS matter.
Potash plays an important part in the forma-
ton of starches and sugars, but it's greatest
Importance Is in connection with protein
formation, in which it is apparently indis!.
pensable. When it is remembered that pro-
TENS OF the related heterogeneous. compounds
are the main source of food for the young
growing cells, the importance. of potassium
will be appreciated.
A ready supply of potassium. also has+ens
and perfects the maturing of plants.
especially the ripening of the wood of fruit
and other trees. A lack of potash is sail by
Weber to cause in the orange all excessive
growth OF weak, immature wood. The same
writer also calls attention to- the fast hat
many growers believe that potash, at least in
the form Of st'phate. causes the production
OF excessively sour fruit. It would be inn
portant to determine if this is really true.
There are good physiological reasons which
lead us to expect such a result, not only III
the orange, but in plants in general. How
ever, an increase of starch or sugar would
also be expected at the same time. The
acid juices of plants are, as q rule, disliEel
by insects and fungi. This may explain why
muriate Of potash prevents, to some extent.
the rayages of the rust mite on cotton.
Clay soils, especially clay loans, usually
contain from O5 to O8 per cent, of potash,
lighter loans about O3 per cent, aud deep
sandy soils less than OIL per cent but even
this small amount is equivalent TO $500
ID. to tie acre, assuming that an acre
Of land l foot deep weighs $780, O0 H.
AS a rule, therefore, it is only upon
the lighter sandy soils that q lack Of
potash may be expected. In the use
OF potassic fertilizers careful attention should
be given to their composit ion. Muriate. OK
chloride OF potash, aud The sulphate are
examples of common potash fertilizers IN use.
The former is as a rule cheaper, and, for
some crops, just as god as the eulphate, and
sho Id therefore in these cases be used. The
sulphate is preferable for certain crops, and
when doubt exists, is much safer and more
satisfactory. This is especially true in the
case of tobacco, which requires a proportion
in the leaf of about 6 parts of potash to 1
part OF chlorine to be of good burning quail.
ty. Night soil, kainit, and other manures
rich in chlorine should not be used for to.
bacco.
Wood ashes contain a great deal of potash,
but practically the whole amount used for
manurial purposes is obtained from the
mines at Stassfurt, Germany, which appear
to be almost inexhaustible. The price of
this fertilizing constituent has remained
practically constant during the past fifty
years Agricultural News, End May.