June r, 1888,] THE TROPICAL AGRICULTURIST, 
8x 7 
PADDY CULTIVATION: 
Pulverizing and Consequent Changes in this Soil— 
Clav Soils — Alumina and Docjule Silicates — 
Poonac as a Manuhe — Coconut and 
Oastok-Oakk, &,c. 
-25th April 1888. 
In connection with Mr. Cochran's analysis of paddy 
soils a new face on the question of pulverizing soils 
has been opened, and your Siyanu Korale correspondent 
has drawn some valuable deductions from the same. 
It is quite true that the injurious ferrous compounds in 
the soil is made innocuous by exposure to the uir ; but 
I don't think it as the principal cause for the iucreased 
results obtained by ploughing with English ploughs. 
In some soils there is no ferrous oxide at all ; 
und in others we find only very little. The real value 
of thorough ploughing is the yielding of more plant- 
food for the use of the growing crop, liy oxidation and 
carbouificatiou caused by the air and accelerated by 
the suuheat many of the dormant compounds become 
active or soluable in water. When the injurious 
ferrous, compounds such as (Fl,-0 4 ) are exposed to 
the air, oxygen is readily absorbed, and the insoluable 
compound of ferrio oxide (Fl.^-Oa ) is formed. This 
compound also plays a great deal in fertilizing a soil. 
Though it is insoluable in water (and hence not 
entering the plant), it has the power ot absorb, 
ing nitrogenous matter and yielding it to the 
growing plant, aud sometimes it readily parts of 
its oxygen also when required by the plant. 
Ferrous oxide is not the only injurious substance 
found in the soil aud improved by aeration. 
There are the foul organic acids ; these acids are 
present to a large extent in most of our paddy soils 
formed by the decay of grass and stubble. Such 
substances are also improved by thorough aeration 
and turned into valuable plant-food. However, no 
one as far as I am aware has determined the amount 
of materials in a soil turned into the activo state 
by aeratiou within a giveu period of time. Some such 
results would be very valuable as showing the difference 
between thorough ploughing und ordinary ploughing. 
The whole amount of active matter generally lound 
in a fertile soil is not above four per cent of its whole 
weight. 
Must of our Ceylon paddy soils consist of clay to 
a mure or less- extent. Clay soils contain a deal of 
alumina and silica generally in the form of alumi 
uum silic ite. It is quite admitted that alumina does 
not euler into the composition of plauts, and silica 
too only in very small quantities. These upparoutly 
useless compounds occur in the soil to a large extent, 
sometimes above fifty per cent of the weight of a soil, 
though they are apparently useless, aud some may 
suppose-, ' playiug no part in the vegetable economy.' 
Alumina and silica play a great deal in the growth of 
a plant and is of great service to the crop. The 
silicate of alumina forma compounds in the soil called 
double silicates, and the nature aud importance of 
tin double silicates may be gathered from the follow- 
ing paragraph Iroui Prof. Tanuer: — 
"Although it • <t luminal forms no portion of plaut- 
food necessary for the structure ot our cultivated 
crops, it bus othor duties devolving upon it which 
utuivuidably associate it with the pluut-lood itself. 
(The doublu silicates) are silicatcH of alumina and 
sumo second substance. The silica ban two part- 
DBU ; the ouo alumina is a permanent partner, 
whilst the oilier may either be soda, lime, potash, 
or ammonia; ami m euuscquouco of the silicate having 
two partner*, tbeno compounds are known as double 
silicates. It may be us well to call to remembrance 
the fact that when tile doublu silicate of aluiuiua 
and soda meets with limu in the soil, the soda is 
thrown out of partnership ami the lime is taken in, 
and the nuw product is a double silicate of alumina 
and lime. Il this double silica to comes iu contact 
wi K potash, tln'u the limo is turned nut and tho 
potash is adiuiltcd us n partner, and the new firm is 
known as doublu silicate of alumina and potash. Km 
il uiiimoliia ghould lie hrouglil in eont.iet with this 
double silicate, then the potash bus to give plnco to 
the ammouin. 'hits it will bu seen thut iimuiouiu is 
103 
the highost favourite, the potash the second, the 
lime the third, and the soda the fourth; and a higher 
favourite always puts aside any other of lower rank. 
At length a period arrives when another agency is 
brought into action, and that is the ' demand made by 
the growing plant.'" 
Thus we see alumina playing a great deal in the 
vegetable economy and supplying plant-food to the 
crop, and this is the reason why many of the clay soils 
containing above fifty per cent of alumina aro richer 
than other soils. 
The value of poouac as a manure for paddy has 
been diseusssd lately, and the relative value of castor 
cake and coconut puonac ; the former is by all means 
better, but from the following table got from the 
analysis of Mr. Hughes, it will be seen that castor 
cake ooutains from i to i more of nitrogen thau 
coconut poonac. 
00 , 
as <U 
oj 
,s is 
Contains p * 
Nitrogen 713 
Digestible fibre ... 1P26 
Mineral water ... 10-68 
But I was eurprized at a statement made by your 
Siyaue Korale correspondent that castor cake contains 
one twenty times as much nitroyen as coconut poonac. 
If it is not a mistake made by him through somo slip 
of the mind, we would be glad to know from where he 
got the information. 
The cultivators of paddy if they go to employ poonao 
at all will resort to their village chekku stulf, 
instead of going for the trouble and expenses in getting 
down castor cake. The only deficiency in coconut 
poonuc is its less percentage of nitrogen ; brown castor 
oake contains about 1 per cent more of nitrogen. There- 
fore l\ cwt. of coconut poonac will contain nearly the 
same percentage of nitrogen and a great deal more of 
digestible organic matter anil mineral water than one 
cwt. of castor cake ; and a l\ coconut poonac will be 
cheaper and convenient for our goyias than a cwt. of 
castor cake. 
W. A. D. S. 
m 
w OS 
1° 
:onut 
mac Mil 
Coconut 
Poonac 
Chekku. 
|l 
CO *• 
o o 
4-39 
3-35 
3-02 
21-89 
6-12 
41-25 
1046 
l 
43-06 
7-80 
cen'. 
INDIGENOUS TEA PLANTS. 
Wh t is an " Indigonous Tea Plant?" I think 
there is a good deal of confusion regarding this 
subject, and therefore purpose giving a short sketch 
of what I really consider to be such. To commence 
with, the tea we term iudigeuous, and which the 
Natives call "junglee," shows pretty plainly that 
the plant is part of our virgin forest or scrub land, 
which has nevor been subjected to cultivation. Tho 
plant may be divided into various classes according 
to the district it is found in, such as Assam indi- 
genous, Cachar indigenous, Tipperah indigenous, &c, 
but ns to whether any of these plants differ from 
one another, is much to bo doubted. I for my 
part take them all to be one and the same pUut, 
not as yet generally known by their botmical 
name among the majority of planters, and for this 
reason the) H" hy the names of the districts in 
which they are found. That the three districts by 
which I have named these iudigeuous plants may 
slightly vary, owing to different local surrounding, 
soil, temperature, kc, there is no room for doubt 
Some are hardy, others aro tho reverse, but all tho 
same they are ono and tho same jiit of plant. 
I must make a slight digression hero, ami refer 
to what is generally termed Muuipore indigouous. 
That inofa a plant exists there ia no doubt, but it 
is one and the samu class as those alrea.ly men- 
tioned by me, its foliage being the same, a light 
greenish V' How. A word ns to the d.irk leaf p ant, 
which is much sm tiler in thu loaf, and which, to 
my mind, is only a hybrid, hnring been the otf- 
■pring of thu light-loafed plant, hybridiied by Ohiua 
