196 
THE TROPICAL AGRICULTUKIST. 
[Sept. 1, 189K. 
Of the "other conbtituents" referred to ia the 
analysis, the chief one is Carbonic acid. Small quan- 
tities (if Chlorine and Suli)hurio acid al o (c urred in 
all the samples. Tha pre euoe of Oxi'^e of iron was 
also detect' d in all tlie samplps. In the leav k and 
pods the p eseii' e of Ojiide of Maiif,'ane8e was distinctly 
evident. Prom the presence of Chlorine the pr-seure 
of Sodium in fmall proport ou may aho be inferred iu 
all the sanipleH. 
From tue data in the foregoing tables may ba cal- 
culattd, first, the amount of the more important plant 
food ingredients, from the agricultu'ist's point of view 
which go to l)uil i up a cacao tree of four and a half 
years old; aud, second, ths aiiioun's of the same 
constituentB required for a crop of seeds aud pods. 
Estimate of the amount of the mere important 
plant-food ingre diosts in a cacao tree of four and a 
half years old ; — 
Tablk C. 
Stem and Leaves & 
Koot, primary smaller Total. 
branch, branches, 
lb. lb. lb. lb. 
J^itrogen ... -0385 -1200 •2421 -dOTS 
Lime .. ... -1226 ■;i410 •f)751 10390 
Magnetfia ... -0473 -1152 •1243 -2808 
Potish ... -1484 -3403 -4301 -9188 
Phosphoric acid ... 'OlGl -0494 '0748 -1403 
As the trees were planted 12 feet by 12 feet apart, by 
multii lying the results in the last table hy 302, the 
amounts of plant food required for an acre of .such trees 
is o itainiid. Estimate of the amount of the more im- 
portant plant-food ingredients in 3112 trees, planted on 
one acre : 
Table D. 
St?m & L'aves & 
Boot. primary tmaller Total 
branch, blanches, 
lbs. lbs. lbs. lbs. 
Nitrogen ... 11-627 38-233 73-205 123 065 
Limo ... 37-025 102-982 173771 £13-/78 
Magn'sia ... 14-285 34-790 37-539 815-014 
Potash ... 44-816 103-771 130 893 277-477 
Phi.sphoric acid 4-802 14 919 22-590 42-371 
In btiihiiug up the tree, lime 's thus the dominant 
ingredieot, amongst those of v.'hich the agriculturist 
has to taki) account; thea come, io orJer, Potash, Ni- 
trogen, Magnesia, aud Phosphoric acid. 
In like manner may be calculated the amonnt'i of 
the more important plant-food ingredie;its assimilated 
hy a year's crop of seeds and pods. The Cacai ilintr-r 
looks for a crop of from 2^ to 3 cwtp, of cured Cacao 
beans. For this esiimate I sball take a year's crop al 
1 lb. perfectly dry Cacao beans per tree, ani 1.26 
lb. dry pods, or 302 lbs. bairns per acre, and 380 lbs. 
pods per acre. 
Bstiaiate of tbe amounts of the more important 
plant-food constituents in a crop of 302 lbs. dry Cacao 
beans, and 380 lbs. dry Cacao pods grown upon one 
acre;— 
Table E. 
Seeds. Pod;. Total, 
lb lb lb 
Nit-ogen . . . . 6-97 5-32 12-29 
Lime ... ... -72 3-33 405 
Magmsia ... 1-77 3-66 4-43 
Potash ... ... 8-85 1897 22 82 
Phosphoric acid ... 3 24 1-70 4 94 
The total amounts of the five ingredients of plant-food 
in the tree, and in the fruit respectively, may now be 
Bet side by side for comparison. In tho case of the 
former, I do not take into account that the leafage is 
renewed from two to three times each year, as appears 
from some observations made by Mr. J. B. Carruthers. 
The leaves are returned to the eoil, and I understand 
„roa: cacao planters that there is very little absolute 
oss of leaf to the estate by wind and wash, 
I Comparison of the amount of the more important 
elements of plaut-food in 302 Cacao trees, 4^ years 
old, and in 0119 year's crop oi fruit (seeJs and potls.) 
TABLE F. 
'J'rec. 
Fruit. 
Total. 
lb. 
lb 
lb. 
... 123-07 
1229 
135 36 
... 313-78 
4 05 
317 83 
... 8001 
4-45 
yi Ot 
... 277-48 
22-82 
300-30 
. . 42-37 
4 94 
47-31 
Nitrogen 
Lime 
Magnesia 
I^Otash 
Phosphor c acid 
The-e is, still, one more iotere^tinK .etima-i- aud 
compari^on to mak-. An e'liniatx of the anioni;t 'f 
plani-fo d rtmoved from tl e m I by tlin annuil io. 
crement to tie tutjgta'ce of the tri-e will enable a 
comparison to be made with the amount of plnt>t. -cod 
removed by cop a< pc-r lablj K. a-Jdthe two Hmountt 
adde 1 to?etber wi'l give aa appronmati n to tbe 
amount of plaut-fcod lem ved from thu soil ann<jally. 
In the estiaate of the auL-aal iacre'i'Cnt to the tre», 
1 have no data of an cxast uatire; iodee', tfce in- 
crement will not be tbe Fame for a^iy tvoy.ars; bnl 
for this caloula'iou 1 sf-all assume "that a lour and a 
halt year old tree rray double its w i-rht by a > addi- 
tiopal 5 )ears of growth. If, then, the weight given 
i'l column No. 1 of table F be divided by 5, th • quotients 
will be an approximation to thr) average amounle of 
plant-food removed p. r annutn during tlie neit live 
years, in building U" 302 Cacao trees. 
In the f jlljwi- ? table. 
No. 1 is ao eatimat^ o? the amoun's nf pla-;t-food 
removed iroai -in acre of toil, by the annual incre- 
ment to the trees only 
No. 2 is an cslimata of the amounts o' pla it.foodi 
removed fro u one acre aunually, both by tfc<; iiicre- 
meat to the trc^s, and by a • rop of Oarai seeds 
only. T In pads are suppoEed to have been teiumed 
to the soil. 
No. 3 ii an estimate of tie amounts of plaut-food 
removed frjm one acre annually by t'le increment to 
tha trees, aud by a crop of Cacao Eesdsand pods. 
TABLE G. 
No. 1 No. 2 No. 3 
lb. per aore. lb. per acre. lb. per acre. 
Nitrogen ... 24-61 31-58 30-90 
Lime .. .. 62-76 03-48 6681 
Magnesia ... 17-82 1900 21-75 
Potash ... 55-50 5935 78 32 
Phosphoric acid ... 8 47 11 71 13-41 
In the cas I io which the rol-husks are burnnd, and 
the a-hfsonly relumed to the soil, ir.e lotal Nitrjg<-n 
rem ved a uually from th; soil by tree and erop 
will be as iu No. 3, the othpr items ia No. 2. 
Tho Cic 10 tro- is usually cultivated under sh ide treen, 
which act as Nitrogen collectors, aud which, of course, 
store up a c rtaiu am^nnt of plant-food in ihe<r 
ti-rsncs, which is, fierefore, removed from the foil. 
Both the shade trees and th-- Cacao 'ree? require after 
a time to bs pruned. The application of tbe above 
calculations to the manuring o the Cacao tree can, 
therefore, only be on generil lines, subject tc modific- 
ation by experie- ce, and to iuc.eieel knowledge of the 
wan'.s of the shade trees. 
MANUEING. 
In the West Indies, the good Cacao soils appear, 
from published analyses, to be markedly richer than 
Ceylon soils in respect of Lime and Magnesia, in 
respect of Potash, the average is also higher than 
in Ceylon ,- but iu respect of Nitrogen and Phos- 
phoric acid, the soils of the West Indies have no 
superiority. It is regarded as essential to a good 
Cacao soil that it should be well drained. The 
dampness, due to an undrained condition of the 
soil, or to overshading or overcrowding, is regarded 
in the West Indies as conducive to a diseased con« 
ditirn of the pods. 
The Cacao tree, we have seen, has a very" good 
proportion of Phosphoric acid, distributed through the 
tree with a concentration of it in the seed. Any 
deficiency in this constituent in the soil will, there- 
fore, afiect more especially the fruit-bearing power 
of the tree. We have seen, further, that all parts 
of the Cacao tree are rich in Potash, with concen. 
tratign in pods and seeds, that Lime is the pcedomi^ 
