376 QUEENSLAND AUXICULTURAL JOURNAL. [1 Ocr., 1899. 
have continued to thrive and to bear good crops of fruit year after year without 
manuring. There is, however, a limit to the productiveness of all soils, and this 
is now being shown in the case of many of our older orchards where the roots 
of the trees occupy the whole of the ground, and the available supply of plant 
food has or is about to become more or less exhausted, and the health, vigour, 
and productiveness of the trees to deteriorate in consequence. 
The knowledge of how best to obtain and apply the plant foods required 
by any particular soil in order to obtain the best returns from any particular 
variety of fruit or farm crop constitutes the science of manuring, and the 
practical application of this science of manuring is of the first importance to the 
fruitgrower who wishes to make fruitgrowing a commercial success—that is to 
say, to raise the most fruit of the best quality that his particular soil is capable 
of producing. 
As the principles of the science of manuring apply not only to fruit 
trees but also to the growing of all kinds of farm crops, I purpose widening the 
‘ate of this article somewhat beyond that of fruit culture, as I believe that a 
little practical general information relating to the manuring of vegetables and 
farm crops will be of value to many who combine fruit culture with vegetable- 
raising or general farming, or with both. 
WHY IS MANURING NECESSARY? 
Ti has been shown by chemical analyses and practical experience that, in 
order for a soil to be capable of producing any particular crop or crops, that 
soil must contain a sufficiency of all the plant foods in an available form that 
are required for the proper development of such crop or crops; and if any one 
or more plant foods be present in insufficient quantity, then the soil can only 
become fertile by this deficiency being made good—by the application to it of a 
manure containing the particular plant food or foods in which the soil 1s 
deficient. 
Some of our soils are poor naturally, and are incapable of producing satis- 
factory returns without the application of manure, but in others the deficiency 
is due to injudicious cropping—viz., the growing of one particular fruit or farm 
crop year atter year—which has exhausted the soil of one or more of the par- 
ticular plant foods required by the fruit or farm crop. This exhaustion of the 
soil may be obviated to a great extent by judicious cropping and cultivation, 
especially by planting a rotation of crops, taking different plant foods from the 
soil instead of growing the same crop year after year, till it has completely 
exhausted the soil in the particular plant foods that are required for its proper 
development. Where exhaustion of the soil is due to injudicious cropping, it 
is advisable to give the land a rest from the particular crop that has exhausted 
it, to replace those plant foods of which it has become depleted, and to grow 
another crop altogether. 
In all soils, excepting possibly very rich alluvial, which will stand cropping 
for a large number of years without becoming exhausted, it is found that even 
with the best methods of cultivation and the rotation of crops the virgin 
richness of the soil becomes gradually decreased, and this is due, not only to 
the loss of plant foods removed from the soil by the crops grown off it, but also 
to the loss of plant foods that are washed out of the well-tilled land by heavy 
rains. ‘This is seen in the case of our rich volcanic scrub soils. At first they 
are friable and rich in humus, but with cropping they gradually become less 
friable, more compact, and comparatively poor in humus, so that their fertility, 
which is remarkable at first, decreases rapidly and can only be renewed by 
judicious manuring. 
Many soils are also rich in one or more plant foods, but are deficient in 
one particular plant food, and such soils become fertile when the particular 
plant food in which they are lacking is supplied to them by manuring. ‘These 
few illustrations will, I think, suffice to show the necessity of manuring, 
