1 Ocr., 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 381 
see any appreciable results from the application of potash salts to the soil 
there, either in the case of pines, bananas, pulses, corn, or sorghum—though 
they certainly improved the colour of citrus trees. Generally speaking, T do 
not consider that the application of potash as a manure will be found to be of 
any great benefit to the greater portion of Queensland. soils, though in the case 
of thin soils—where it is found to be deficient—its application as a manure 
will have a rapid and marked result, both on fruits, vegetables, and farm crops. 
Tn many of our soils there is abundant potash, which is, however, in a more 
or less unavailable form, and this supply can, as a rule, be liberated by the 
application of lime to the soil, as previously mentioned under the heading of 
ct no,” or by the growing of deep-rooting pulses that are valuable for green-crop 
manuring—a matter that J purpose dealing with fully later on. 
There are three great sources of potash, viz.:—Granite, which consists of 
quartz, felspar, and mica; and it is the felspar, of which there are several 
yarieties, that contains the potash, one variety (orthoclase) containing as much 
as 16 per cent. The second great source of potash is galt water, which contains 
about 7°6 Ib. of potassium chloride in 10,000 Ib. of sea water, so that the supply 
from this source alone is inexhaustible. The third great source, and the one 
from which we obtain our supply, is the great deposit of potassium salts that 
are found near Strassfurt, in Germany, where the Supply isenormous. From the 
crude salts we obtain kainit, which is largely used as a manure, and which con- 
tains, in good samples, about 25 per cent. of ‘sul 
equivalent to about 12% per cent. of potash (I, O), 
prices is 5s. 4d. per unit—that is to Say, & manure containmg 1 per cent. of 
potash is worth 5s. 4d. per ton, or a manure containing 10 per cent. is worth 
£2 13s. 4d. per ton. Kainit at present price is a very dear form in which to 
buy potash, as it costs about £4 per ton, whilst sulphate of potash containing 52 
per cent. of potash is worth £13 15s. per ton, and muriate of potash containing 
61 per cent. of potash is also worth £13 15s. per ton, so that the cost per unit 
is less than that in the case of kainit, besides the freight and handling on an 
equal quantity of available potash is much © 
} greater in the case of kainit than 
itis in that of the more concentrated manures. 
In addition to these sources of potash, there are two others, viz. :—(1) What 
is known as Australian potash, a natural potash salt found in this colony and con- 
taining 25 per cent. of potash; though not offered for sale in Queensland, as 
far as I am aware, it is now quoted on the Sydney market at -€6 per ton, at which 
rate, taking into consideration the 8 per cent. 0 insoluble phosphates combined 
with the potash, and worth 2s. per unit, it is the cheapest form of potash avail- 
able, costing only 4s. 2d. per unit. (2) Nitrate of pota 
’ sh, or saltpetre, which is 
valuable both on account of the potash and nitr 
Eg trogen that it contains, As a 
_ general rule itis, however, too dear to use, but in Special crops, such as asparagus, 
it is found to be a very valuable manure. 
The ashes of many trees are also rich in potash, but only when they are 
grown on soils containing a sufficient supply of potash. The ash of trees 
growing on poor sandstone soils seldom contains much potash, and is often of little 
value as a manure. When used in conjunction with other manures, which is in 
many cases desirable, sulphate of potash should be used ; also, when the question 
of railway carriage or long cartage 1s to be considered, it is preferable to kainit, 
as it only takes one-fourth the amount. 
Sulphate of potash is most beneficial when a 
spring, just as they are starting into growth 
readily assimilated by the tree. If the soil is of & very open porous nature, it is 
better to apply the manure in two or three dressings at intervals rather than all 
at once, as, if applied all at once and heavy rains set in, a considerable portion 
will be leached out of the soil and lost. This applies equally when soluble 
phosphatic or nitrogenous manures are applied to light porous soils. 
rom 1 ewt. to 2 ewt. per acre of sulphate of potash is about the quantity 
required to produce a good crop of grapes, plums, 
and prunes, and though oranges 
and Jemons contain rather less potash in proportion than these fruits, yet the 
BL 
pplied to the trees early in 
» as being in a soluble form ‘it is 
