July 1, 1898.] 
THE TROPICAL AGEICULTUBIST. 
25 
SCIENTIFIC MANURING: 
MR. JOHN IIUGHES-MK. A. BAUR— AND 
THE LATEST CONTINENTAL AUTHO- 
RITIES. 
Before <Urecting our '-eaders' attention to the 
following conmninication from Mr. Job.n Hu;,'h8S 
— who always writes after an instructive fashion 
— we would explain that I lie passage Mr. Hnglies 
condemns in the editorial of Observer of April 6th 
which he quotes, was e.\press'y given by us as a quo- 
tation from the writings of one ot ilie most distin- 
guished Agricultural Chemists of the present day. 
Moreover our attention was called to this deliverance 
hy Mr. A. B uu — who semis us another letter on 
n'tr )gen in the manuring of tea — and for wliom Mr. 
Hug'ies has commendation to offer towards the end 
of the following communication. We are now en- 
ableil to give the information Mr. Hughes desiderates 
as to the identity of llie Agricultural Chemist. He 
is Monsr. M. P. F. Deherain, member of the In- 
stitute of Scie!ie«, Paris, wdiose work on ''Science 
and Agriculture" was jiublished in Paris {Kuelf 
& Co., 103 Boulevard St. Germain) in 1897, and 
is entitled "Micro-organisms or Bacteria in the 
Earth"* and from this volume we quoted. "With 
this preliminary explanation, let us hear what 
Mr. Hughes has io say: — 
" A leading article in tlie Overland Observe?' of 
April 6th under the heading of 'Science and 
Manuring' is naturally calculated to attract con- 
siderable attention not only in Ceylon, but also in 
India and China and wherever tea is cultivated. In 
tills article the following paragraph has no doubt 
attracfed special notice and well deserved hostilecri- 
ticism :— ' We proclaim, not as a projjhecy but with 
certitude; tlie reign of the nitrogenous manures is 
(inisliedanil that of the Bacterias commences,' Who 
the luthor of so definite a statement may be does 
not appear; but it may safely bestated without fear 
of contradiction by tliose well informed that the 
reign of nitrogenous manures is very far from being 
over; and this fact may be illustrated by the 
enormous quyntities of guano, nitrate of soda 
ana sulphate of ammonia that are annually ap- 
plied both directly, and as important ingredients 
in mixed manures wlierever artificial or chemi- 
cally prepared fertilisers are applied. 
"It is somewhat surprising that such a state- 
ment as that contained in the above paragraph 
shoulil have been published in a paper which has 
always been so iustly regarded as the medium of 
a'$-ording planters sound practical advice. 
" Let me quole the opinion of the late Agricul- 
tural Chemist to the Royal Agricultural Society 
of England when reporting upon some analyses 
of Australian soils sent to the writer by the 
Agent-(ieneial for CJueensland : — -'As regards the 
relative rapidity with which the fertilising 
matters are removed by growing ci'ops and natural 
drainage, nitro','en is the first which goes, and 
in relatively I.w^^aji pioportions than any of the 
essential mineral plant constituents, and hence 
there is the greatest necessity to make ample 
provision for the restoration of nitrogenous food 
which is constantly being eliminated from the 
land by the growing crops, and to a very large 
extent in the drainage (see Voelcker's analyses 
of drainage water from experimental plots at 
Rothampstcd).' This statement is just as correct 
now as when it was written upwards of 23 years 
since Nitrogenous manures must, however, be used 
with moderation especially if they are employed 
in a form readily soluble in water such as nitrate 
• M. Deherain is in charge of the best known 
licultural Experimental Station in France. 
4 
of soda, nitrate of potash, sulphate of ammonia 
or even as guano. This caution is specially im- 
portant to bear in mind in tropical or semi- 
tropical climates with a heavy rainfall like that 
associated wiili Ceylon. It is for these reasons 
that the writer in recommending fertilisers for 
tea, coft'ee and cacao has found it desirable to 
treat each estate or groups of estates according 
to their special requirements as indicated by 
previoas analyses of selected samples of soil. 
Wiiere the nitrogen naturally present in the 
soil is comparatively large, the percentage of nitro- 
gen in the manure recommended was naturally 
comparatively small and the proportions of phos- 
phates and potiish salts were comparatively large: 
When, however, as in most Ceylon estates the 
hgures for nitrogen are low, and in cases where 
the original rich humus of the surface soil has 
been washed away, it is reasonable, and indeed 
requisite to raise the percentage of nitrogen. 
Also at higher altitudes much more nitrogen is 
required than in low altitudes. In fact as I have 
already stated if manuring is to be carried on 
with due regard to science it is necessary to 
treat each locality according to local circumstances 
of soil, situation and season. A recent writeij 
Mr. A. Bar.r has correctly pointed out that it 
does not seem reasonable to apply nitrogen in a 
readily soluble form while phosphates are sup- 
plied in a form only slowly soluble. Jn a pro- 
perly compounded manure for tea a certain pro- 
portion of all the necessary elements of plant 
food should be supplied in a form at once avail- 
able and the remainder of these constituents in 
forms and conditions of dilTerent and less soluble 
character. It is only by careful attention to 
these and other poixts that manures can be 
economically applied, and it would be very im- 
practicable as well as decidedly unscientific to 
prescribe any definite formula for a tea manure 
without regard to the composition of the soil, 
the altitui'e of the estate, the situation as regard 
exposure to wind, and the average rainfall ex- 
perienced. JoH\ Hughes, f.i.c, 
Agricidtural Analyst." 
"79, Mark Lane, London, E.G." 
No doubt Mr. Hughes will refer to Mr. Dehe- 
rain's book and will, in due season, give his o))inion 
of it. He may also have something to say about 
the present letter of Mr. Baur who tells us that 
average tea soils have enough nitroge" (and to spare) 
year by year,ior 1,600 lb. of made tea per acre— 201b. 
of nitrogen being equal to 400 lb. of made tea. 
He further indicates how this may be increased 
by stirring the soil; and also by ©ur tropical rains 
which are notoriously rich in nitrogen. Now it 
seems to us that each practical planter may well 
settle the question at issue for himself. Surely 
he can afford to set aside a few acres for an 
experiment while going on treating the rest of 
his estate as usual? Let him hole a couple of 
acres as for manuring, but put nothing in — filling 
in the holes after the usual interval and repeat- 
ing this operation year after year for three 
years. Another two aci-es let him treat as 
directed by Mr. Baur ; and a third in the 
old and most approved fashion with castor- 
cake and bones. Let him keep a note of the cost 
and returns in each case for the three years 
and he will then have an object lesson more 
valuable to him for his estate, than can be 
offered by all the manure sellers or Agricultural 
Chemists in the world. He should take care 
that the six — or even three —acres of the estate 
selected, should be as near as he can decide, a 
fair average of the property. 
