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phates, and thus more readily taken up and assimilated by crops. 
A good dressing consists of 2 to 4 cwt. per acre; or, in conjunction 
with faxm-yard manure, 2 ewt. 
Whenever using superphosphate, better results are obtained 
when the soil contains a sufficiency of lime, i.e., enough carbonate 
of lime to cause effervescence when a mineral acid is poured on to 
it. On land poor in lime it is advisable to use a larger weight of 
“basic slag” if it can be procured at a reasonable price, or bone 
meal or a mixture of superphosphate and bone meal. Basic 
phosphate or superphosphate mixed with a small quantity of lime 
and thus “reverted” is also preferred on soil poor in lime. 
Fermented Bones can readily be prepared on the farm by mix- 
ing with bone one-third their weight of earth or burying them in the 
manure heap, moistened with water, urine, or liquid manure, 
and covering the whole heap with earth. After a time, depending 
on the temperature, the bones enter into fermentation, and crumble 
to powder, when they are dug out and used. Fermented bones act 
more rapidly than raw bones, and can be compared in their action 
to bone superphosphate. 
The relation of phosphoric acid (P,0,) to phosphate of lime 
(Ca,P,0,), such as is expressed in soil or manure analysis, is as 
142 is to 310, or a fraction less than half. Thus bonedust containing 
50 per cent. of phosphate of lime contains somewhat less than half 
this amount of phosphoric acid, or, in exact figures, 22.58 per cent. 
To convert the one into the other multiply the phosphoric acid by 
2.18 (in practice 2.2) and the percentage of phosphate of lime is 
obtained. Conversely, divide phosphate of lime by 2.2 and the 
equivalent percentage of phosphoric acid is shown. 
PorassIuM 
is the constituent of a fertile soil or of fertilisers which ranks third 
in costliness. It does not occur as such, but as combinations, such 
as chloride (muriate), sulphate, carbonate, nitrate, silicate, ete. 
Potash is also known as potassium oxide (K,O), and as such is 
reckoned when valuing fertilisers. 
In manures it occurs as sulphate and as muriate (chloride of 
potassium), the sulphate form being a little more costly than the 
muriate. 
’ The chief sources of potash are— 
Wood Ashes, which constituted for a long time the chief source 
of supply of potash used for agricultural purposes. The incom- 
bustible part of “ash” of farm crops and timber contains from one- 
fourth to one-third its weight of potash. For this reason newly 
cleaned land, well timbered, on which the wood has been burnt oft 
the ground, will have a supply of potash proportionate to that con- 
tained in the ashes. Western Australian firewood usually leaves 
ashes low in potash, except the Peppermint (Agomis fleruosa), 
which, says E. S. Simpson, contains nearly 6 per cent. of potash. 
