THE CAUSES OF THE FERTILITY, ETC. 
45 
tion, and found that the amoun tof bacteria in soils increases 
when a small quantity of superphosphate is given to it, but 
will decrease if the dose of superphosphate is increased. 
Ihis explains why a heavy manuring with super- 
phosphates docs not pay in our wheat lands, while a light 
manuring, say up to one cwt. per acre, gives certainly satis- 
factory results, as then this phosphatic manure acts in two 
ways : first, as a direct fertilizer ; second, as a stimulant on 
the action of soil bacteria. 
For probably a somewhat similar reason I have found 
that superphosphate is not a good manure in the sands of 
our coastal districts, and that blood-manure is far better. 
Apart from the percolation, which is very great in sand and 
allows the superphosphate to be leached" out of the sand 
much quicker than the blood manure, which is not so readily 
dissolved, there is the fact that blood manure is very rich 
indeed in bacteria and therefore inoculates the sands, which 
in their natural state carry a comparatively very poor flora 
of bacteria. Superphosphates, needless to say, contain no 
bacteria. 
There remain a few words to be said as to the influence 
of the potassic manures (sulphate of potash) on the growth 
of the wheat plants in our dry eastern districts. 
While there is no doubt as to the increase of the cereal 
crops due to manuring with potash in other countries, there 
is no evidence to show that this is so in our wheat lands ; 
on the contrary, experiments have so far given negative 
results. 
Prof. Lowrie, when in this State, told me that he 
was very much astonished at this result, and personally 
repeated experiments have convinced me that if sulphate of 
potash is given together with superphosphate and the seed 
no advantage results. 
1 am not prepared to make a definite statement yet as 
to why this should be so. My experiments so far have been 
limited to plants in pots and field experiments, which through 
the kindness of some friends will be carried out next season 
and will have to confirm the result before it may be regarded 
as correct . So far I find that if sulphate of potash is given to 
the soil about three to four weeks before the wheat is sown, 
a marked increase in the crop results. If it is given to- 
gether with the seed, and in the drill, then the germination 
is invariably bad, and a small crop the result. This points 
to the fact that perhaps the sulphate of potash remaining in 
immediate contact with the seed for a prolonged period and 
in a hot and dry seed bed, as it does in our wheat areas, in 
some way injures the embryo or later on the first rooted 
of the germinating seed. But, as I said, my experiments 
