August 2, 1909 
cause of the unsatisfactory results that 
were sometimes obtained, after a con- 
tinuous use of superphosphate, was to be 
~ found. 
The process of the manufacture of 
superphosphate is very simple. The. 
phosphate rock is ground to a fine pow- 
der, it is then treated with sulphuric acid 
to convert the insoluble phosphate to a 
water soluble and acid soluble state and 
render them available as a plant food. It 
is in the quantity of sulphuric acid used 
to accomplish this result that the prin- 
cizal cause of the trouble may be attri- 
buted. 
In most of the imported superphos- 
phates there will generally be found an 
excess of sulpuric acid’ In a climate 
like England or the Continent, where 
they have a heavy rainfall, this may not 
be found injurious, as the sulphuric acid 
is to a certain extent leached out of the 
gronnd, but in wheat-growing areas of ~ 
Australia, where the rainfall is much 
more limited, it has been found that the 
sulphuric acid accumulates in the 
ground. Sulphuric acid is a powerful 
fungicide and an insecticide, and when 
present in the ground in such large 
quantities it destroys many of the 
beneficial soil bacteria which are neces- 
sarily present in the ground that has a 
high fertility. 
In the manufacture of Mt. Lyell super- 
phosphates the minimum quantity 0 
sulphuric acid is used to produce the 
necessary conversion from insoluble to 
soluble phosphates, and this to a large 
extent accounts for the superior results 
obtained by its use in every part of the 
f 
THE AUSTRALIAN GARDENER. 
Commonwealth. It is not generally 
known to what extent the use of sulphuric 
acid enters into the use of superphosphate 
and when it is pointed out that every ton 
of superphosphate contains only 10 ewt. of 
phosphatic rock, the balance of the added 
bulk being made up with sulphuric acid 
and moisture, it will be recognised that 
this is the primary cause of the gradual 
falling off of crops where imported 
superphosphates containing excess 
of sulphuric acid are continuously 
used. 
It may be authoritatively stated, how- 
ever, that where superphosphates are 
used which contain only sufficient sul- 
phuric acid to render them soluble, that 
no injurious effects will be noticed from 
their combined application. On the 
other hand, it has been demonstrated that 
where sufficient superphosphate of the 
right kind is used, there should be an 
appreciable increase in the crops. It 
must, however, be remembered that no 
manure will take the place of good culti- 
vation in the seasons, and that on these 
factors are largely dependent the success 
or otherwise of the crop. 
Miscellaneous Items. 
In Canada, stock have to be artificially 
fed fully six months, if not more, every 
year. 
Tunis Cra: 
Making tracks is nct always desirable. 
If you do not believe it, walk across. the 
newly-scrubbed kitchen floor with your 
muddy boots. 
29 
There is probably nothing ‘better for 
starting lucerne than“wood ashes. Ashes 
contain both lime and potash, with more 
or less phosphorous. All these the soil 
needs. aie eats 
TiptaeesT pipet} 
During the last ten years over 80,000 
tons of wattle bark has been produced in 
South Australia, equal to considerably 
more than half a wt Mats pounds sterling 
in value. 
US peeeicee 
When young, lucerne is quickly des- 
troyed by weeds, and it. must, therefore, 
be sown on clean land and cultivated the 
first year. When once established it can 
take care of itself. | 
Veet T 
While ix may, no doubt, be advisable to 
admit of some exercise for the sake of 
keeping the ‘animals in health, yet the 
pigs that quietly eat their food and take 
their rest will always fatten readily, 
inosine 
There are three kinds of . cultivated 
barley—the two-row, the four-row, and 
the six-row.. The aim of seed improvers 
is to get the productiveness of the six- 
row with the quality of the two-row. 
t Tt t 
Basic slag may be used on many kinds 
of land. It responds well on clay soil 
deficient in phosphoric acid and lime. 
The lime in this manure has an invalu- 
able effect on seemingly worn-out lands. 
te aie Pa 
When applying lime it should be 
remembered that this substance has a 
tendency to sink in the soil. Darwin has 
shown that the action of earthworms is 
one way by which lime is drawn down. 
It is better to apply small quantities at 
short intervals than a large quantity at 
one time, 
