Feb. 1, 1894.] Supplement to the " Tropical- Agriculturist.''^ 
573 
6. The formatiou of this calcareous stratum 
beneath the soil is very interesting from an 
agricultural point of view ; for much of the 
good effect of the numerous irrigation wells by 
means of which the Jaffna peninsula is cultivated 
like a garden, is due to the fertilizing in- 
fluence of lime dissolved in the water. It will 
be useful in this connection to mention that 
although water containing lime in solution is 
good for irrigation it is not so for cooking 
purposes, especially for cookitig pulses such as 
dhall and gram, as limewater forms an insoluble 
compound Avith the nutritious principle called 
legumin. and thus tends to harden the pulses 
and makes them difficult of digestion. Hard-water 
{i.e., water containing lime) is also said to cause 
urinary disorders ; and it is not improbable 
that diabetes which is a too common complaint 
in Jaffna may be in some measure due to the 
lime dissolved in the water used for drinking 
and culinary jjurposes. 
7. The sand which covers a vast e.\tent of the 
peninsula, and in which the coconut and palmyra 
palm grow freely is, according to Sir Emerson 
Tennent, a transported soil, and has been carried 
hitherto by currents from the coast of Southern 
India sweeping down across the Palk's Strait 
and striking on to our coasts. To c undents such 
as these is also attributed the red soil called 
chempadu which extends over some considerable 
area, and which, unlike the soil in most part of 
.laffna, is very fertile. Its deep red colour is 
owing to the admixture of iron, and being 
largely compo.sed of lime from the comminuted 
coral underlying it, it is susceptible of the highest 
cultivation and produces crops of great luxu- 
riance. 
8. The freedom with which solanaceous plants 
such as tobacco, briujal and chillies, and legu- 
minous plants such as pulses and beans grow 
in Jaffna may be chiefly accounted for by the 
richness of the soil in lime obtained from the 
underlying calcareous stratum, and the lime con- 
tained in the irrigation water which has already 
been mentioned. For it is a well-known fact 
that these two classes of plants require a com- 
paratively large proportion of lime. The predo- 
minance of sand in the chemimdu and other 
fertile soils imparts a looseness of texture to 
tliem and makes them specially suited for the 
free growth and development of the various 
kinds of yams and roots ranging from the 
purple ' king yam " downwards. 
9. The formation of the soil of Jaffna makes it 
liighly suited for fruit culture. Its dry porous 
substratum of coral formation affords a natural 
imder drainage ; and it may be that the secret of 
the success of the grape vine in Jaffna may lie 
in this peculiarity of the soil. Almost all .laffna 
fruits in general have been spoken of in high 
terms, the grafted mangoes, the delicious oranges, 
pomegranates, grapes, \'c. coming iu for praise 
from strangers who have tasted them. But here 
too as in other parts of the Island, fruit culture 
is capable of much development, and sucli a 
paying concern as grape culture, which is at 
present more or less confined to the town, may 
well be cxttuided to other suitable parts of the 
Peninsula. 
E. T. HOOLE. 
{To he continued.) 
THE SOIL-mVERTI^'G PLOUGH. 
No. 11 of the Agricultural Ledger Series edited 
by Mr. Edgar Thurston, reporter on Economic 
Products to the Government of India, gives some 
evidence in favour of the soil-inverting or mould- 
board plough over the native implement of 
India, which is not very different from that used 
also in Ceylon. Of the improved ploughs we are 
told that they are generally made wholly of iron, 
and fitted with a broad curved piece called a mould 
board, which inverts the furrow slice, that is, 
turns it upside down. The beam is of wood 
like that of the country plough, and is connected 
with the yoke in the usual manner. The idea 
that the soil-inverting ploughs are too heavy of 
draught for country bullocks is said to be un- 
founded, as they have been drawn by cattle with 
the same ease as the country plough. 
In order to compare the soil-inverting plough 
with the native implement, two plots on the 
Dumraou Farm, each 800 square yard, were 
ploughed up and both cropped with wheat, and 
treated exactly alike in all other respects. The 
cost of cultivation was the same iu both plots. 
The increase in outturn obtained by means of 
the inverting plough over the outturn obtained 
with the country plough is shown below : — 
YEAR: 
Grain per acre. 
Straw per acre. 
In- 
crease. 
De- 
crease. 
In- 
crease. 
De- 
crease. 
1885- 86 
1886- 87 
1887- 88 
1888- 89 
1889- 90 
1890- 91 
Mds. s. 
2 16 
1 14 
1 33 
1 4 
2 4 
0 30 
Mds. s. 
Mds. s. 
3 21 
1 8 
l"'35 
4 16 
0 19 
Mds. 9. 
;;; 
0 "l4 
Average ... 
1 24 
2 12 
0 14 
Both the plots having been continually under 
wheat for several years and received no manure, 
their outturn was gradually decreasing. In 
1891-92 it was, therefore, thought desirable to 
change the crop ; and the experiment was accord- 
ingly discontinued on the two plots, which had 
been hitherto reserved for the trial. It was, 
however, made in two other plots, with the 
result that the use of the inverting plough gave 
1 maund 26 seers of grain and 3 maunds 1 seer 
of straw more per acre than that of the country 
plough. The result leaves no doubt that the 
outturn of wheat can be increased to a certain 
extent by the use of the soil-inverting plough. 
The effect of soil inversion was equally 
conspicuous on paddy. The trial with this 
crop was carried out in exactly the same way 
as with wheat. The results are shown in the 
Increase of grain 
Increase of straw 
per acre. 
per acre. 
Mds. 8. 
Mds. X. 
1886 
... 1 6 
9 16 
1887 
... U .35 
2 38 
1888 
... 1 8 
2 8 
1889 
... 3 1 
6 2 
1890 
... 0 24 
3 20 
Average ... 1 15 
1 33 
