August 23, 1883. ] 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
153 
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COMING EVENTS 
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Dundee (three days) ; BasiDgstoke. 
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14tii Sunday aftee Teinitt. 
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Royal Horticultural Society; Fruit and Floral Committees at 11 A.M. 
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Colchester Show. 
GARDEN CHEMISTRY—POTASH. 
LL soils need tlie application of nitrogen, most 
of them need phosphates, but whether potash is 
also required depends to a great extent on the 
nature of the soil cultivated, some having 
abundance, others being destitute of that neces¬ 
sary compound. Most fertile clays contain a 
practically inexhaustible supply of potash. In 
the Carse o’ Gowrie, for instance, it exists to 
the extent of 2 per cent, in the soil. Supposing the roots of 
plants never to penetrate deeper than 9 inches, a supply of 
45,000 lbs. is thus within their reach in an acre ; but 
gardeners would not rest satisfied till by trenching and the 
addition of manures the staple was at least 18 inches. Not 
including the potash added by the manuring as usually done, 
this would bring a supply of potash within reach of the roots 
calculated to afford sufficient for the wants of 700 crops of 
Potatoes of 10 tons each crop, and this crop takes up more 
potash than any other—certainly more than the usual 
average rotation of a garden. Even when only 0-1 is present 
more than enough for all requirements exists, but only when 
present in an available form, which it often is not, and may 
then be nearly as well absent. Caustic lime liberates potash 
from some of its compounds, and thus renders it of use to 
the growing plant. M. Ville maintains that it should always 
be present in artificial manures ; but his experiments, and 
those of others on which he bases his assumption, have 
evidently been conducted in soils peculiarly deficient in 
potash, or only containing it in an unavailable form, for with 
the same crops others have found the application of potash 
not only quite unnecessary but perfectly ineffective. 
In addition to wdiat we have termed fertile clays, loamy 
soils on the old red sandstone, and often on the new, are 
generally rich in potash. Experience has proved that for 
the most part such soils are peculiarly well suited for the 
cultivation of fruit trees, and especially Vines. The Vine 
requires, above all things, potash, phosphoric acid, lime, and 
nitrogen. Lime rubbish is universally added to vinery 
borders, and occasional supplies given as top-dressings 
from time to time—or should be. With potash plentifully 
present, only bones are wanted to supply phosphates and 
nitrogen ; while a continued supply of the last is kept up by 
applications of liquid manure and dressings of soot, guano, 
and other rich manures. In such soil Vines must thrive if the 
atmospheric conditions are right; but if the potash should be 
absent, and it frequently is, they could not possibly do so. 
The soil would then be blamed, but that would not help 
matters. It is just in such difficulties that science steps in 
and puts matters right. 
Most trap soils contain an abundance of potash, and such 
are always found to produce very excellent Potatoes, Clover, 
and other leguminous crops. But even some traps are by 
no means rich in this. Granite is almost always very poor 
in everything else, but rich in potash. For this reason fine 
Potatoes are grown in districts north of the Grampians that 
refuse to grow corn till lime and phosphates are added, and 
for this reason fine Grapes are not uncommon in such soils. 
Trap rocks are generally composed of felspar and hornblende, 
the felspar yielding much potash, the hornblende much lime ; 
hence trap soils are rarely benefited by applications of either 
lime or potash. 
Potash almost always requires to be applied to poor 
sandy, gravelly, chalky soils, as well as to peat, and also 
clays derived from shales of the carboniferous strata. In the 
Carse of Falkirk occurs a clay rich in potash, but here the 
clay is the silt carried down by the Firth, Carron, Teith, 
Allan, and Bonny from the degrading traps and old red sand¬ 
stones over a very wide area. Here the farmers contemn the 
use of potash. A few miles to the south-west barren shale 
clays abound—barren, that is, except where redeemed by the 
application of manures, potash included, and then the barren 
clay becomes notably fruitful, proving that barrenness depends, 
not on texture or even on geological peculiarities, but on the 
presence or absence of required plant foods. Gardeners will 
thus see that soil need be no hindrance to the best results. 
Plants possess very different powers of attacking the 
compounds of potash in the soil. Thus a plant which requires 
a great quantity may not be benefited by its application, 
while others which require very little may be greatly benefited. 
If present at all, for instance, that excessively robust Potato 
Scotch Champion will almost certainly find and utilise it. 
On such soils applications would do little good. If absent, 
however, the case is quite altered. Then a hundredweight 
or two per acre will produce startling results compared with 
undressed ground ; but the weakly growing varieties of 
precisely the same species, with weaker foraging powers, 
apparently are unable to attack the potash compounds, and 
hence manures rich in potash help such immensely. Thus, 
though a knowledge of the mineral constituents of a plant 
will afford no certain index of that plant’s foraging powers 
or ability to attack certain substances, the fact that any 
given plant demands any given compound largely is proof 
positive that that peculiar compound must be plentifully 
present, and that making plentiful provision is always the 
safe side to err on. It also points the way to a rational 
system of rotation of crops, and indicates the value of the 
ashes of any given plant. 
Among fruits Grapes (the ash of) head the list with over 
60 parts in the hundred, and as other eight compounds are 
present the preponderance of potash will be apparent. Apples 
follow next, with a varying amount of something between 85 
and 68. Plums follow with 59, Pears 54, Cherries 51, Pine 
Apples 49, Cucumbers 47 (a detailed analysis of the Melon 
I have not been able to find, but the fruit and seeds are 
peculiarly rich in potash and phosphoric acid), Gooseberries 
38, Figs 30, Strawberries from 21 (when soda partially takes 
the place of potash) to 49 (when soda is absent). Other 
fruits contain less than 30 per cent., and for the purposes of 
the cultivator may be “ lumped.” 
Among vegetables Potatoes come first with an average 
per-centage of fully 50, but rising to 73 in some soils with 
some varieties, and going as low as 42 with others ; Rhubarb, 
the stalks of which give 59, French Beans 49, Broccoli 47, 
Beans (Windsor) 45, Artichokes 44, Beet and Onions 89, 
Cabbages from 31 to 39, Celery 37, Peas 36, Leeks 33. Some 
authorities give 44 as the per-centage in the ash of Spinach, 
but others give soda as being largely present and potash only 
sparingly so—the soda replacing the potash apparently. 
The same thing occurs with the Strawberry. 
The rule is very general that potash and phosphoric acid 
are always largely present in plants that are used for food by 
men and animals, and in those parts that are especially used. 
In poor foods they are less plentifully present than in more 
nourishing ones. The starch of the grains and roots and 
the cellulose of green vegetables, with the sugar and pectose 
of fruits—substances all chemically allied—is always associ¬ 
ated with potash, and their formation depends on its presence; 
while the gluten of Wheat, avenin of Oats, legumine of Peas 
and Beans, the albuminoids generally that occur in vege- 
