UXE 1, 1898.] 
TilE TROPICAI. 
AGRICULTURIST. 
^otjresponiScnciA 
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^0 ^ ^' 7 / ^ 
BOUGHT TEA LEAF— AND INDIGENOUS 
J AT— VEHSUS LOW AVERAGE ERICES. 
Anibagamuwa, April 19. 
Dear Sir, — Talking on the .subject of tea prices, 
I met a gentleman the other day, who was 
realizing a 7d to 8d avera,ge whilst his neighbour 
on the adjoining estate was only able to get 6d. 
I naturally remarked “ you are plucking fine?” 
“ No ’’—said my friend— “ I go round every 9lh 
day ; you cannot call that fine plucking ! ” “No” 
— said I — “ I do the same, but yet I cannot get 
up to your aveiage.” My friend promptly 
put in,— “But you buy leaf outside don’t you? 
that accounts lor it,” Q'here is mucli in that, 
no doubt. Same evening I met his neighbour 
and in course of conversation reverted to (he talk 
I had with the other neighbour and told him all. 
“Well,” said he, “he may be plucking medium but 
don’t you know be lias a very large acreage of 
low jat Hybrid or China tea and this generally 
helps to give him tiie prices !” If this theory is 
correct, 1 fear our indigenous teas have had 
much to answer for, for the present depressed 
state of the market. I always firmly believed in 
a good Hybrid. It will do its 50U lb. per acre 
with cultivation and give a fair average, while 
the indigenous, with its fabulous yields, helps to 
put in a coarse tea in every grade and thus 
brings down our average. Indigenous, I say, above 
4,900 feet, nowhere else. C. T. 
[This is surely rank heresy ? “ Indigenous ” 
grows best at a low elevation and the finest 
field of “ China” in the island is at Nuwara 
Eliya.-Eo. T.A.] 
BONE-MEAL, NITRIFICATION, AVAIL- 
ABLE PHOSPHATES. 
Colombo, April 25. 
Sib, — Referring to the subject of the Value of Bone- 
dust as a Fertilizer, dealt with in an article which 
appeared a short time ago in the T.A. I beg to 
offer a few remarks. It has been pretty well de- 
monstrated by Professot Wagner and others that, 
in temperate climates, and for most crop.s, phos- 
phoric acid is more economically supplied in the more 
readily soluble forms, such as superphosphate and 
Thomas’ phosphate powder, than in bone meal. This 
is more especially the case with crops which require 
much phosphoric acid, and which have to be ma- 
tured in a few months. Thus, for cereal crops, 
which remove per acre 20 lb. or so of phosphoric 
acid from the soil in a few months, soluble phos- 
phates have a great advantage over undissolved bone 
manures. The advantage is not so great in the 
case of daily pastures, which remove about 12 lb. 
phosphoric acid, and remove it in more regular pro- 
portion throughout the year. Hence, for the manur- 
ing of permanentpastures, undissolved bone manures 
are still much in request. 
For tropical products, which assimilate much phos- 
phoric acid, as, for example, the sugar-cane, the 
great superiority and economy of soluble phosphates 
over bone-meal has likewise been demonstrated. The 
canes alone of the sugar-cane plant remove per 
crop 401b. phosphoric acid, and 41 lb. of nitrogen 
per acre. The soils in ibe sugar-growing Island of 
Hawaii are particularly rich in organic nitrogen, and 
in phosphoric acid ; but both of these ind ispensahle 
elements of plant food are present, for the most 
part, in a comparatively inert state. Thus the 
Director of the Hawaiian Experimental Station says, 
105 
»5S 
that " SO lb. of nitrogen, given in an available 
form, is of more moment to the growingterop than 
the 17,000 lb. of organic nitrogen lying inert in each 
acre of land.” In like manner, it might be stated 
with regard to the phosphoiic acid in these sugar- 
growing soils, that an application of pho.sphoric acid 
in the soluble form is of scarcely less moment to 
the growing crop than the large quantities at pre- 
sent existing in these soi'S ; but rendered compara- 
tively inert by being in combination, to a great 
extent, with iron and ahimimim. On these soils, 
bonemeel produces but little effect except in the 
w'ettest districts, whereas the response to an ap- 
plication of soluble phosphates is most marked 
and the effect almost immediate. If an organism, 
capable of nitrifying the large stores of inert nitro- 
gen could be introduced into these soils, little nitro- 
genous manure would be required. Meanwhile the 
planters find the most profitable manures are sul- 
phate of ammonia and soluble phosphate, while 
the formula for manures most generally recom- 
mended by the Agricultural Bureau gives' six per 
cent nitregen, eight per cent phosphoric acid solu- 
ble in water, and potash to suit individual soil. 
An abundant crop of tea, say 800 lb per acre 
removes 39 lb of nitregen from the soil, ind is 
therefore, comparable w’ith the sugar-cane in this 
respect ; but even an abundant crop of tea removes 
from the soil only a little over six lb of phos- 
phoric acid, so that here comparison does not hold. 
It has to be borne in mind however that the tea pru- 
nings from good average bushes have been shewn 
to take up somewhat moie phosphoric acid and consi- 
derably more nitrogen than are removed by crop. The 
tea crop, thus, requires much nitrogen, and only a mo- 
derate amount of phosphoric acid, and this explains 
the present system of manuring, according to which 
phosphoric acid has, for the most part, been sup- 
plied from the slowly available form of bone-meal, 
while the applications of nitrogenous manures have 
been on a liberal scale. The soils in which bone- 
meal gives the best results, are soils with plenty 
of organic matter, and very little carbonate of lime. 
The presence of much carbonate of lime hinders 
the decomposition of bone-dust, no doubt owing 
to the fact that the solvents of the soil act more 
readily on the carbonate than on the phos- 
phate of lime as it exists in bone-manure. Ceylon 
soils contain very little carbonate of lime. 
Hence the solvents of the soil, carbonic acid, the 
more complex organic acids, and nitric acid, are 
more free to act on the bone phosphate. It is the 
custom to add nitrogenous organic manures, such as 
oil-cakes, along with bone manure; the decomposition 
of these produces acids W'hich assist in bringing 
the bone phosphate into an available state. More 
than a fourth part of the bone dust itself consists 
of organic matter, and contains about 4 per cent, of 
nitrogen. The complete nitrification of four parts 
of nitrogen produces 18 parts of nitric acid ; which, 
if saturated with lime from the bone phosphate, 
would remove therefrom eight parts of lime chang- 
ing part of the phosphoric acid into more soluble 
forms. In like manner, the nitrogen of the oil-cakes by 
nitrification reacts on the bone meal. We thus find 
that the subject of nitrification, besides having a 
direct interest as nature’s method of rendering organic 
nitrogen fit for plant food, has also a collateral in- 
terest, as assisting in the p>roeess of rendering the more 
stable phosphates, such as bone-phosphate, available 
for plant food. It is interesting, theretore, to note the 
results of some experiments, on a small scale, published 
by Ph. Boname on the rate of nitrification of the organic 
matter in a typical soil of Mauritius, and of certain 
nitrogenous manures, all of which are used in our 
Ceylon tea-soil The Mauritius soil is rich in nitrogen, 
and poor in lime, and the climate favourable to 
nitrification. In the unmauured soil, nitrification was 
greatly promoted by an addition of carbonate of lime, 
and still more so by caustic lime The nitrogenous 
manures experimented with were Sulphate of Ammonia, 
dried blood, oil-cake and fish guano ; and the result of 
a series of experiments, without addition of carbonate 
of lime or \inae, showed that fish guano nitrified 
