THE TROPICAL AGRICULTURISt. 
[JuLT I, tigi- 
portions as good cattle manure. The three tables 
of tlieoretical doses will be found very helpful in 
compounding mixtures. 
Tims, suppose we take Ceylon cattle manure 
No. 1 as representing, which it does, a good 
sample of cattle manure, we see that 8,7.54 lbs. 
contains 39-04 lbs. of nitrogen, 23 lbs. of plios- 
phoric acid and 83-14 lbs. of potash, whereas tlie 
strictly theoretical doses would be 39-04, 6-08 an<l 
20-16 respectively. It will ])e thus seen tliat 
8,754 lbs. cattle manure No. 1 contains in round 
numVjiers one tlieoretical doso of nitrogen, 4 of 
pliQsplioric acid and 4 of potash calculated for the 
tea drop only, and tiiat iu like mauner for the 
tea crop and prunings 21, .339 lbs. contaiji api)roxi- 
niately one theoretical dose of nitrogen, 4 of phos- 
phoric acid and 4^ oi potash. Althougli arti- 
ficial mixtures compounded so as to ))reserve tiie 
same relative proportions of the three most impor- 
tant ingredients of plant-foo<l as they are found 
in good cattle manure might form a good starting 
point for a series of field experiments, expprience 
would in all probability demonstrate that those 
proportions will be modified with advantage in 
the direction of an increase of the phosplioric 
acid and a reduction of the potasli.* The commer- 
cial salts of potash are all so soluble that when 
these, are added in considerable quantity to tlie 
Boil much is apt to be lost in tlie drainage water. 
Hence it is more economical if the plant can 
be stimulated, to supply itself, for the most 
part, with potash from the soil supplemented 
by manures, which, like castor cake contain 
potash in a less readily soluble form. 
* In the case of coffee, as will be noticed in 
tl»e next Chapter, the ordinary expe'-ience of the 
planter in manuring, has led him to adopt pro- 
pprtions of manurijil ingredients widely diverging 
from the theoretical quantities, thus J lb. oi 
caistor cake anfl J lb. of bone-dust per tree contain 
plant food for coffee in the proportions of one 
theoretical dose of nitrogen, 20 theoretical doses 
of phosphoric acid, and -2 of the theoretical dose 
of potash. 
Examples of conimerciaJ fertilisers specially 
prepared for tlie tea crop will be givei in the 
cliapter devoted to Manures. 
Leaves of the Grecillea RohuisUi. 
As tlie tea plant is found Ui flourish Ijest under 
a certain degree of shade, the tree called gre< illea 
robusta, a native of Australia, has V>een largely 
planted on Ceylon tea estates. Tliis tree serves 
the double purpose of breaking the force of the 
wind and of aftbrding a suitable amount of shade 
for the tea plant. It is therefore interesting to 
ascertain how far this tree compete* with the 
tea shrub for the plant food in the (.oil. With 
this object in view, two ten pound parcels of 
leaves were sent to the author for analysis ; one 
parcel containing 10 lbs. green leaves, tlie other 
10 lbs. of sun-dried old leaves. 
It will be observed from the accompanying 
tables of agricultural analyses of grevillea leaves 
and the comparison of their composition with 
that of tea leaves, that, while the tea leares 
are very rich in the more important constituents 
of plant food, viz., the nitrogen, potash and j-iios 
])horic acid, the grevillea leaves are correBj^ond 
ingly poor in these constituents and are very rich 
in the less valuable lime. The tea and grevillea 
trees are therefore examples of different trees well 
suited to grow together on the same soil. It will 
further be obser^■ed that there is a very consider- 
able difference between the gievillpa green and 
old leaves. The latter shew a smaller proportion 
of ash when calculated upon the drv matter of 
the leaf, and the ash is of inferior quality showing 
more especially a remarkable decrease in the lime 
and potash and a correspondingly large increase 
in the siliceous matter. Supposing' these old leav«» 
to have lain on the ground for »onie time, part 
of this difference might not be in the constitution 
of the leaf ; but might l»e accounted for by 
mineral matter being dissoh ed out and a small 
addition of persistently adhering soil, as an 
amount of atiliering .soil which would add a very 
trifling percentage to the weight of the leaf would 
add a considerable percentage to the weight of 
the ash of the leaf. 
Agricultural Analyses of Leaves of Grevillea Robnsta. 
Green Leaves. 
Old Leaves (Sun dried.) 
ilbisture 
♦Dryittatter ... 
*€ontaiiiing Ash 
Niirogen 
Per cent. 
lbs. per 10 lb. 
Moisture 
*Dry matter ... 
^Containing Ash 
Nitrogen 
Per cent. 
lU. [>er 10 IH, 
50-88 
49-12 
5-088 
4-912 
4-78 
95-22 
-478 
9-622 : 
100-00 
10-000 
IOC 00 
10-000 
3-26 
-53 
-326 
•053 
5-59 
1-019 
-559 
-102 
Dry Matter of Gieen Leaves. 
Dry Matter of Old Leaves, 
••Gtgftiii* matter 
A«h 
*Conteimng Nitrogen ... 
Per eeht. 
Ounces per 
10 lb. Green 
Leaves. 
*Organic matter [... 
Ash 
*Containing Nitrogen ... 
Per centi 
Ouaces per 
10 lb. Old 
Leaves. 49 
(.Sun-dried.) 
93-363 
6-637 
5-216 
94-129 
5-871 
8-944 
l-6tf 
100-000 
'849 
100-000 
1-08 
1-07 
