44 
G. A. pfister: 
Little or no nitrification is going on during winter and during 
the three months preceding the ripening and harvest, i.e., 
during the period of the plants’ strongest growth. The 
cause of this is to be sought in the temperature and moisture 
conditions of the soil. In Europe and America, therefore, 
the nitrates which have accumulated in the late summer and 
autumn are washed so far down by the heavy winter rains, 
the thawing snow and the succeeding spring rains, that they 
are out of reach of the roots of the wheat plants. Hence 
the costly manuring with nitrogenous manures is a necessity, 
for we must not forget that wheat is essentially a nitrogen 
feeder. 
In our climate, or rather in our wheat areas, the matter 
is different. In the first place, in these regions the wheat 
plant, from the moment of its germination to harvest-time, 
practically never stops growing ; there is no long winter 
period during which the plant is dormant. Therefore it 
can avail itself of all the nitrates which have been stored 
up by the soil-bacteria, before they are washed down into 
deeper layers. But our rainfall is scanty and not sufficient 
to leach the soil of its nitrates ; furthermore, the temperature 
and moisture conditions of our wheat-belt are such as to 
fully justify the supposition that here the nitrification pro- 
cess sets in much earlier than in Europe and America, so 
that not only the plants find the nitrate supplies from the 
preceding summer available, but also can make ase of 
the nitrates which are produced during the period of strongest 
growth of the plant. 
You can now clearly see the reason why in Western 
Australia manuring with nitrogenous manures does not 
pay and is not necessary, while in Europe and America it 
is a costly necessity. Indeed, we can pride ourselves and 
consider ourselves highly fortunate that this is so, and 
that Nature has bestowed upon our wheat districts one of 
its greatest riches — nitrogen. 
The manuring with superphosphate has its great ad 
vantages, inasmuch as it is readily available and gives the 
young plants a quick start, so that they can sooner avail 
themselves of the nitrates in the soil. 
But the superphosphate plays yet another role. In 
fact of inorganic substances calcium and phosphorus are 
absolutely essential to the furtherance of the nitrogen 
fixation by bacteria. Now our wheat soils are very deficient 
in lime, and a light manuring with superphosphate of lime 
certainly helps the bacteria in their work, while if the amount 
of superphosphate given is increased there is too much free 
acid, and the bacteria will be hindered in their development 
and work. I have made several experiments in this direc- 
