342 JOUKNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
quantity and condition of its products, the composition of the soil and' 
the class of vegetation upon it. By these means we may know with 
an absolute certainty what elements should be employed and in what 
quantities. 
The calculations and studies which I have made in order to become 
thoroughly acquainted with the composition of the Orange tree cannot 
be applied in every case, since it is known that the growth and production' 
vary very much. 
In order to treat of this important subject scientifically and with a, 
knowledge of cause and effect, we will make use of the average result 
of many analyses I have made of trees under very different conditions, 
which result will serve as a guide, with sufficient exactitude, for tha^ 
rational application, of manures. 
Average of Analyses of the Orange Tree. 
In 100 parts. 
Nitrogen. Phosphoric Acid. Potash. 
Fresh fruit . . . 0-38 0-40 0-38 
„ leaf . . . 0-70 O'lO 0'38 
„ wood . . . 0-70 0-50 0-73 
From the fruit, leaf, and wood, all being freshly gathered, one obtains 
respectively 3-21, 6*00, and 7*00 per cent, of ashes. 
In the case of evergreen trees of slow growth, like the Orange, and 
which are subject to very limited prunings or thinning out of the secondary 
branches, the fertilising elements consumed in the formation of the 
foliage and wood are very slight, consequently no account need be taken 
of them in calculating the composition of the manure. By far the greater 
part of such elements being used in the production of the fruit, to pro- 
perly fertilise we must fix Our attention principally on the quantity of 
fruit the tree produces in order to calculate the fertilising materials which 
will have been taken out of the soil, and in this way deduce what it is 
needs replacing. 
Supposing that a hectare of orange grove (2-471 acres), with about 
250 trees, produces 30,000 kilos. (66,120 lb.) of fruit, according to the 
above analysis the crop contains : — 
Nitrogen ... 114 kilos. (251} lb.) 
Phosphoric acid . . 120 „ (264^ „ ) 
Potash .... 114 „ (2511 „ ) 
and it will be necessary to return the above elements to the soil in one form 
or another if one wishes that the trees should not give way for want of 
nourishment, nor leave off yielding an abundant crop of good quality. 
Bearing in mind the aforesaid figures, the theoretical formula of a perfect 
chemical fertiliser for the Orange per hectare (2*471 acres) will thus be : — 
Nitrate of soda ... 760 kilos. (1,675 lb.) 
Superphosphate of lime . 705 „ (1,554 ,, ) 
Sulphate of potash . . 225 „ ( 496 „ ) 
It is clear, however, that this formula cannot be rigidly adhered to ; it 
