May if 1890.] THE TROPICAL 
condition may be of the most favourable nature, 
it is quite possible that most of the mineral 
constituents may be of the most insoluble kind, 
or of a perfectly useless nature — the necessaty mineral 
ingredients of plant food being absent. Suoh re- 
sults depend on the origin and history of a soil — 
not only on its derivation from particular rocks, 
but its modification by the natural agents, chemical, 
mechanical, and animal. If it oan be proved that the 
chemical condition of a soil is faulty, that it lacks oris 
deficient in one or more of the elements of plant food, 
while the growth on it is healthy and vigorous, then 
can it be said that the principles of agricultural ohemis- 
try are unsound ; while the same conclusion may be 
reasonably come to, if while both the chemical and me- 
chanical conditions of the soil are favourable, the growth 
is weakly and unhealthy — of course assumming that 
the seleotion and planting of seed nuts were well done. 
The existence of isolated areas of unhealthy growth 
must be accouDtel for as being caused either by un- 
favourable chemical conditions, or by peculiarly uncon- 
genial mechanical conditions of soil, possibly by an 
unsatisfactory substratum, or again by carelessness in 
seleotion or planting or seed nuts, or lastly by neglect 
for any period, especially during the early stages of 
growth. As I have stated before a tree whioh has up 
to a certain period appeared healthy and robust may 
begin to exhibit unhealthy symptoms from a deficiency 
of plant food, or moisture (possibly induced by a spell 
of prolonged drought — for water ia neceaeary not only 
for the assimilation of food, but also for its elaborate m 
and for the circulation of sap). This failure in very 
limited areas — more limited than in auy cooonut p'an- 
tation — is often met with in oereal, root, vegetable and 
garden cultivation, and special treatment in various 
ways is necessary where the planting and seed are not 
at fault ; such as improving the mechanical texture of 
the soil, adding either a material such as lime which 
liberates plant food, or some manurial substanoe. In 
eertaiu cases a previous vegetable growth may account 
for the exhaustion of particular elements of plant food. 
It is on consideration of these causes of failure in culti- 
vation that one is impressed with the need for caution 
in the selection of a property ; and where one proprie- 
tor has had the opportunity of selecting bis own seed- 
nuts, watching their growth in the nursery, superin. 
tending their planting out, helping their start in the 
field under the most favorable conditions, — for care 
during the early stages of life whether of the 
plant or animal is of primary importance for 
healthy development in after life — it is here 
that he has the advantage over another proprietor 
who takes over his estate ready planted. Hence the 
importance of a careful enquiry into the history of 
soil and crop to ensure a safe investment, especially 
in the case of trees of a perennial character. This 
Is too much lost sight of. Often after-care and liberal 
treatment will improve the condition of trees and this 
no doubt many have found by experience, can frequently 
be rucces;fully done: but as before mentioned there is 
a limit, and if the effort at improvement entails a cost 
that is not commensurate with the returns that may 
be expected, then such a property must be considered a 
failure. I have iu view au extreme case of this nature 
of an estate most perfectly planted and liberally treated, 
which every attempt to improve without incurring 
financial loss, has signally failed. 
There have been reports from abroid of coconut trees 
(wing affected with disease. In an article by the Hour. 
B. Howell Jones, which appeared in the " Journal of 
tho Royal Agricultural and Commercial Society of 
British Guiana," reference is nude to the disease affect- 
ing coconut trees in Mahaicony, thus : " Here and 
tbere we saw signs of an inexplicable coconut disease, 
not to b3 confounded with the attack of the heetle, 
and on talkiug over the matter, both Mr. Smith and 
Mr. Mustard wore of an opinion that it resulti from 
the planting of green nuts which grow much more 
rapidly tbau ript ones, and that after bearing ono or 
two crops tboy seem to get oxhausted and die away." 
M*. Quelch, curator of the Museum and Kditor of the 
aboverucutioned Jourual, writes me that the disease 
in British Guiana is evidently identical with that in 
AGRICULTURIST. 7S7 
Oeylon, and that it is now manifesting itself by a 
dropping of the half-ripe fruit and branches. I have 
observed this result in some pirts of the Island where 
the attack is bad. The opinion recorded by the Hon. 
Howell Jones is worthy of consideration; The growth 
from an immature nut eanuot be expected to bo a 
healthy one ; bnt whether the nut or the soil be at 
fault, it must be borne in jnind that the disease is 
associated with an unhealthy growth. " The disease," 
says Mr. Quelch, " is common on the different parts 
of the Cocals, but it does not seem to spread to any 
alarming extent." 
Mr. J. H. Hart, Superiniendent of the Botanical 
Department, Trinidad, roferring to the coconut palm 
disease in the West Indies and distinguishing it 
from the attacks of beetles and scaly blight, says 
that traced to its primary source the disease would 
appear to be caused by a state of semi-starvation in. 
duced either by drought or a deficienoy of manurial 
constituents in the soil of the particular district, and 
that where these causes do not obtain it disappears. 
In my own experience I found this to be the fact, for 
during my visits about the middle of last year I 
found certain estates suffering from the effects of 
the prolonged drought which then prevailed and 
showing much discolouration of leaf, but with the 
return of the rains and the measures taken to combat 
the evils arising from a lack of moisture, these 
effects have ceased to appear. On other estates, how- 
ever, the disease does not show any signs of improve- 
ment, and iu such cases I cannot but agree with Mr. 
Hart that the want of a sufficient supply of plant 
food is the origin of the evil. 
I am indebted to Dr. King, analyst to the City of 
Edinburgh and the leading Agricultural Chemist in 
Scotland, for help in the matter of soil analyses for 
which I had no appliances at the Colombo School of 
Agriculture. Mr. John Hunter of the Minto House 
Chemical laboratory referring to the analysis of a 
mixed sample of soil and sub-joil from a part where 
the coconut trees were most affected with disease, 
says, "You will notice that the soil is very low in 
phosphoric acid, and low in potash ; there is an ab- 
normally high percentage of oxide of iron and alum- 
ina.... I may say that a soil recently analysed here 
contained more phosporic acid than your sample does 
and yet was incapable of raising a healthy crop." 
Here I consider we have a flood of light thrown on the 
subject. The well known maxim of Playfair that "it 
is the body in minimo that rules the crop" instantly 
suggests itself in this connection. It may be that 
phosphoric aoid and potash are present in the soil, but 
not in a condition available as plant food, and here 
it is that the importance of the operations which 
favour the liberation and distribution of soluble 
plant food comes in, for a soil may contain an 
abundance of phosphoric acid, potash and magnesia 
and yet be infertile if these exist as apatite, fels- 
par and serpentine. It is needless for me to 
cumber this report with suggestions as to the 
best means of supplying phosphoric acid and potash 
to the soil in a manurial form ; letjme only remind 
owners of estates that they should use the most solu- 
ble manures containing these foods if they look for 
early results, and if they wish to come to the aid of 
their trees before long — as they should. I mention 
this because I know of cases where manures are being 
applied in a most insoluble and almost worthless 
condition. 
But on the texture of the soil depends its powers 
of absordiug and retaining- manure. Now the fact 
that there is an abnormally high precentage of oxide 
of iron would soem to indicate that more thorough 
draining and work up of the soil would tend to a 
better balanoing of the proportions of plant food. I 
am aware that the soils in many parts of Oeylon have 
very large proportions of iron oxide, as analyses I 
have before me show, but in the case in point, this 
prepon deranoe of iron oxid9 is to bo considered together 
with the abnormally low percentage of the most valu- 
able mineral food ingredients of plants. Certain of 
the compounds of iron we know are noxious to vege- 
tation, wbilo " reverted phosphate " of iron ( as euob, 
