Mav s, 1898.] THE TROPICAL AGRICULTURIST. 
7^5 
chemistry during the past 20 years, The planter 
has recognized the necessity of returning to the soil 
certain plantfood ingredients removed by csop ; 
but with regard to the most imrtant and most costly 
of them, he has not been made aware that it is largely 
supplied by natural sources. The consequence is that 
thousands and thousands of tons of nitrogenous 
manures are still yearly being put into the soil, for 
which there is but little necessity. And what con- 
sideration has been given to the other necessary 
manurial constituents ? Very little and that little 
(except by a few) has been given without proper 
discrimination. It is well-known that, for its suc- 
cessful growth, the plant is just as much dependent 
upon one as upon the other plantfood constituent. It 
cannot live on the ready nitrogen first and on phos- 
phoric acid (the yet undissolved bones) later on. Yet 
the most soluble nitrogenous manures are being ap- 
plied along with the most slowly acting phos- 
phatio manures. No wonder therefore that plants 
never do get the full benefit of those large appli- 
cations of nitrogen, and that manuring shoul I prove a 
costly operation. To recognize the necessity of apply- 
ing phosphoric acid and yet to apply it only in a 
slowly available form, as in raw bones, means nothing 
else than to make the plants’ growth dependent on the 
latter. It is therefore indispeusible that phosphoric 
acid and potash should be applied liberally and only 
in a form readily available for the plants in order 
to enable the latter to make full use of the natural sour- 
ces of nitrogen or of any nitrogen applied artificially. 
In my second circular explaining the prin- 
ciple of the fertilizers recommended by Mr, John 
Hughes, for Ceylon Tea, I touched upon the natural 
sources of nitrogen and considering the im- 
portauoe of the matter I may be permitted to refer 
to the subject again. By last mail I received a 
Beport published under the auspices of the French 
Minister of Agriculture, in which the fixation of 
atmospheric nitrogen has been most amply de- 
monstrated. I have already pointed out that certain 
conditions are necessary to induce nitrification (the 
formation of nitrates by micro-organisms), of which 
warmth, moisture, and the presence of oxygen may 
be stated as the moat important. In Europe nitrifi- 
cation is intercepted during the cold season, a good 
deal of the nitrates that are formed during sum- 
mer and more particularly during autumn, get lost 
during winter through drainage and percolation, and 
in spring the soil is not only particularly deficient 
in nitrates ; but owing to the lethargic state of the 
micro-organisms the formation of nitrates is going 
on at its slowest just when the growing vegetation 
stands moat in need of it. That is why it has been 
found necessary to assist the growing vegetation by 
an artificial supply of nitrates, in the form of nitrate 
of soda. It had, however, been discovered that if 
some soil is taken from the field in autumn and 
during winter maintained in a warm room, where, it 
is kept moist by the addition of water and occa- 
sionally stirred up, the formation of nitrates went on 
uninterruptedly. Some French agricultural chemists 
decided to give this lesson a practical appli- 
cation. For this purpose a certain number of ex- 
perimental plots were set aside and planted. One 
series was manured with cattle dung and in addition 
with 2 cwt. of nitrate of soda (containing 15 per cent 
of nitrogen) per acre. The other series received an 
equal quantity of cattle dung and in addition 2 cwt. 
of nitrifying earth per acre. This nitrifying earth, as 
explained above, was nothing else than natural soil 
taken from a field in autumn, and maintained 
during winter in a state favorable for nitri- 
fication by being kept in a warm room, where it was 
occasionally stirred tip and kept moist by the addition 
of water These experiments were first undertaken 
in 1896, repeated iu 1897, conducted independently 
at different places and with different crops During 
their growth the plants which were thus differently 
manured, shewed no difference in appearance, and when 
the produce was taken from the fields it was found 
that in most instances a better crop was obtained 
from the plots which had received this nitrifying 
earth than from those which had received the 
nitrate of soda. To still further demonstrate the 
influence which this nitiifying earth had on vegeta- 
tion, two plots were set aside and planted. One 
received an application of 2 cwt. of nitrate of 
soda and the other of 2 cwt of nitrifying 
earth without any other manure being added, 
nor had the two plots been manured the previous 
year. The results again justified expectations, 
for t he crop from the field which had received the 
two cwt. of nitrifying earth exceeded by about 10 
per cent the crop from the field which had received 
ti e two cwt. of nitrate of soda (which latter w.as equal 
to an application of five cwt. of best white castor cakes 
per acre). This favorable action of the nitrifying earth 
is not to be attributed to the insignificant quantity of 
nitrates introduced into the soil, but to the inter- 
vention of the micro organisms, which, being main- 
tained in full activity during winter, continued their 
work of fixing the nitrogen from the atmosphere and 
of rendering it available for the plants. If, however, 
they can succeed at home in doing away with the 
necessity of applying special nitrogenous manures 
why should not the same be possible out here 
where there is no winter to intercept nitrj- 
fication ? With such a damp climate, even 
temperature, and well-distributed rainfall, it 
may be taken that the most favourable conditions for 
nitrification are fulfilled by nature ; and those who in 
spite of this continue to apply large quantities of nitro- 
genous manures do so uselessly and entirely against 
their interests in a monetary sense. Therefore let 
those who want good crops and who desire to make their 
cultivation pay go in for manuring liberally with 
phosphoric acid and potash, which ingredients 
are almost always deficient in soils and 
they will reap the benefit of the natural sources 
of nitrogen. Instead of saying I cannot afford to 
manure, they will, by adopting the right principle, 
find that, as at home, it will pay them handsomely 
to do so. It is not the cost, but an injudicious 
selection of manures, which makes manuring an 
expensive item. 
In his climate the Ceylon Planter has a most 
powerfull ally, and if he will only take advantage of it, he 
will be able to hold his own : and it will not be for him, 
but for his competitors in the North of India, in China, 
and Japan, to fear the effect of low prices — I am, dear 
sir, yours faithfully, 
A. BAUR, 
The Ceylon Manure Works, 
Colombo, April 4th, 1898. 
No. II. 
Sir, — I n my last letter I drew attention 
to the natural sources of nitrogen, which 
under our climatic conditions render the applica- 
tion of large quantitie.s of nitrogenous manures 
unnecessary. 1 have pointed out that we owe 
these natural sources of nitrogen to micr«-organ- 
isnis living in the soil which fix the nitrogen of the 
atmosphere and convert into nitrates the organic 
nitrogen already present in the soil. The conditions 
favourable for nitrification are equally favorable for 
the fixation of the atmospheric nitrogen and con- 
sist in warmth, moisture, &c. When these condi- 
tions are fulfilled the micro-organisms acquire 
an extraordinary activity and it has been found 
that even without the aid of nitrogenous manures, 
the nitrates thus formed are usually in excess 
of the requirements of the most exacting crop. 
Unfortunately these nitrates are not capable of 
being fixed in the soil and cannot be stored up 
for future use as is the case with 1 hos)ihoric 
acid or potash. Any excess or any nitr.ates that 
are not taken uji by the plants immediately are 
carried oft' and get lost through drainage and 
percolation. Thus when the conditions for the 
existence of these micro- organisms cease to be 
favourable, the formation of nitrates diminishes 
iu proportion, a scarcity of nitrogenous food 
