THE CULTIVATION OF OEANGES. 
343 
'must be modified in each particular case, in accordance with the composi- 
tion of the soil and the nature of the vegetation of the orchard. The 
formuhie which will be given further on are based on this, and modified in 
accordance with the experience of some years. 
It is necessary first to find out the composition of the soil. This pre- 
supposes a delicate analysis which only a chemist can make, and although 
it may involve a little expense, the certainty one obtains of applying the 
■exact fertilisers which the tree requires, without adding elements which 
might possibly be prejudicial or at least wasted, compensates with interest 
for such expense. 
In default of the above analysis, a knowledge of the physical qualities 
of the soil is to a certain extent useful. A clayey soil presupposes richness 
in potash and poverty in phosphoric acid ; a limy soil is, on the contrary, 
generally rich in phosphoric acid and poor in potash. Sandy soils are 
nearly alw^ays poor in all fertilising materials, and the soils charged with 
•organic matter contain a sufficient amount of nitrogen. Consequently the 
formula must be slightly modified in accordance with the quality of the 
soil, adding or diminishing the elements in which it is deficient or 
abundant. 
To appreciate the effect of a fertiliser it is also necessary to bear in 
mind the nitrogen that the soil absorbs from the air and renders soluble. 
With regard to potash it must be remembered that the Orange tree, 
like many other plants, is capable of absorbing large quantities of it with- 
out the increase of absorption being shown by an increase in the crop or 
improvement in the quality of the fruit. With potash there is the same 
result as with soda and lime. In a soil containing, for example, common 
salt (in such limited quantity as to permit horticultural operations), the 
plants grown therein absorb soda in abundance, and soda must not be 
imagined on this account to be an essential element ; for the same plants 
in a soil wanting in chloride of sodium will make luxuriant growth 
without the absorption of the smallest quantity of the said element. The 
Olive, for example, when grown in a limy soil, absorbs large quantities 
of lime and thrives well. Nevertheless, I have seen very luxuriant Olive 
trees in soils containing hardly any lime, and the analysis of the different 
parts of the tree showed very slight quantities of oxide of calcium. 
When once the manurial necessities of the plant regarding potash are 
satisfied, if the roots find more at their disposal, they continue absorbing 
it and depositing it in the green organs, where by accumulation it acts 
mechanically, as lime and silica would operate, in making the mineral 
<;overing of an organic structure. 
Besides it must not be forgotten that a great number of soils contain 
an abundance of potash, and that in order to utilise the same it is only 
necessary to reduce it to a state fit for absorption, using for this purpose 
gypsum, green copperas, or other organic fertilisers. And all this natu- 
rally suggests a diminution in the quantity of potash referred to in the 
previously mentioned formula. 
The fertilising materials have very varying effects on the Orange, and 
it is necessary to be acquainted with these effects in order to apply the 
fertilisers according to the requirements of the market, or to attain the 
desire of the grower. An excess of nitrogen produces an exuberant growth 
