378 QUEENSLAND AGRICULTURAL JOURNAL. [1 Ocr., 1899. 
matter, but have not stated what Ainds of organic and inorganic matter. Tt is 
considered by competent authorities that the following elements are essential to 
the proper development of all cultivated plants, and that the absence of any 
one is detrimental to such development :— Oxygen, hydrogen, carbon, sulphur, 
silicon, chlorine, sodium, manganese, magnesium, iron, caleium (lime), 
potassium, phosphorus, and’ nitrogen. Of these, the first two are always in a 
readily available form in water, and carbon is always present in the air in 
sufficient quantity, so no further notice need be taken of these three. ‘The 
next xix elements in the list are, as a rule, present in all soils in sufficient 
quantity for the growth of all crops, excepting, in certain cases, Magnesium, 
which forms about 17 per cent. of the ash of almonds and about 13 per cent. 
of the ash of quinces. It is seldom necessary to apply magnesium as a manure 
by itself, as if the land is limed there is usually enough magnesium mixed with 
the lime to supply all requirements. Should it be necessary to apply 
magnesium as a manure, then a dressing with kainit will answer the purpose ; 
kainit containing a large proportion of magnesic chloride. This reduces the 
list to five; and of these five, one—viz., iron—is usually present in sufficient 
quantity in most soils, excepting possibly some of our poor “ wallum” soils, 
which are, as a rule, useless for cultivation, as, in addition to being very poor 
in plant food, they are usually very sour and badly drained. 
Tron is present in the soil in two forms: a ferrous form which, when it is 
present in too great a proportion—oyer 1 per cent.—renders the soil valucless, 
as it is injurious to vegetation. 
Tron in the ferrous form imparts a yellowish colour to the clay subsoils in 
which it is usually met with, and, when present in this form in excessive 
quantities, the remedy isto drain the soil, thereby aérating it, and exposing the 
ferrous salts to the air, when they are rapidly oxidised and conyerted into ferric 
oxide, or, as it is commonly known, iron-rust. Lime applied to the soil has a 
similar effect in this case to draining. The other form of iron present in the 
soil is the ferric oxide, or iron-rust, to which the red colour of soils is due, and 
it is in this state that it is taken up by plants dissolved in water. Iron is 
essential to the formation of the green colouring matter, or chlorophyll, of the 
leaf, and its absence in the soil is shown by the sickly or blanched appearance 
of the foliage Should iron be found to be deficient in the soil, it is best applied 
in the form of ferrous sulphate (copperas or green vitriol), which is readily 
conyerted by the action of the air into iron-rust, and is then available when 
dissolved in water for plant food. The amount of copperas required will rarely 
exceed | cewt. per acre; in fact, more would probably do harm, and it is best 
applied in the early spring, just before the active growth of the tree takes place. 
Copperas, in addition to its manurial value, has also a value as a fungicide and 
destroys the spores of many fungus diseases that may be present in the soil, 
such as the oidium of pumpkins, black rot of the tomato, and the potato disease, 
as well as destroying many insects and nematodes. 
The other four elements—calcium (lime), potassium, phosphorus, and 
nitrogen — are those to which the fruit grower or farmer has practically to confine 
himself in determining what manures are best adapted to the growth of the 
different varieties of fruits or farm crops, as they are the ingredients in which 
soils become most rapidly exhausted, and form by far the greater portion of the 
ash of all cultivated plants. ‘They are all absolutely essential to plant growth, 
and when cither of them is present in the soil in an insufficient quantity, either 
due to the natural poverty of the soil or to its impoverishment through cropping, 
the deficiency must be made good by the application of the necessary manure 
before the soil can be made to produce a satisfactory return. In fact, the 
fertility of a soilis calculated on the amount of these elements that it contains, so 
that, in describing the various manures, I will confine my remarks to these four 
elements, and will endeayour to show, approximately, how much of each is 
extracted from the soil by the principal varieties of fruits and farm crops; what 
manures are required to supply the deficit; and how and when it is best to apply 
these manures in order to obtain the best results. 
