January t, 1891,] THE 1 ROPiOAL AGRICULTURIST, 
47- 
SOIL mGREDIENTS, 
Iron . — I kuow of no soil whose contents of ferric 
oxiile ■woiil'i not be more than ample to supply <all the 
needs of vegetation, so far as direct absorption is con- 
osrned. Its ascertained perc’iitage rarely falls below 
1 per cent, and more commonly ranges from 3 to 5 
percent. A curious fact amply illustrated by analysis 
is that soils of high ferruginous color do not always 
contain unusal amounts of the ferric hydrate, the 
color apparently depending more upon the mode of 
distribution than on the quantity. This is obvious 
cLOugh in soil, containing bog ore in visible grains ; 
but in many cases it appears to be a semi-crystallmc 
aggregation of the substance around particles of soil 
aiul sand that hides the tint. The almost universal 
preference accorded to “ red ” soils as against gray or 
whitish lands in the same soil region, has given rise 
to the proposition to render the latter classes equal 
to the first by the addition of iion in some form, even 
to the use of magnetite sand and iron scraps. It need 
hardly be said that the true cause of the prelerence 
given to red lands is chiefly that the presence of this 
color indicates goof drainage, whereas in thi corres- 
ponding “ white ” lands the iron as usually accumulated 
in the subsoil in the form of bog ore in consequence 
of stagnation of water, forming a subsoil in woich the 
process of reduction may recur at auy time, and in 
which (as analysis has shown and as might Lave been 
anticipated) a large proportion of the phosphoric acid 
of the soil has been accumulated and locked up. A 
red soil is a “ safe” one and is usually freed from the 
need of artificial under-draiuage. That the color im- 
parted by ferric hydrate favors the absorption of heat is 
another recommendation of red soils ; they are 
“ earlier ” than those of white or gray tints. More- 
over, as direct determinations show, weli-d ffused 
ftrric hydrate is poweifully hygroscopic, and adds 
materially to the retentiveness of soils for moisture ; 
hence crops on such soils are less liable to suffer 
from extreme heat thau those ou less, retentive land. 
My; former determinations of this factor in the soils of 
Mississippi amply illustrate this point, and O&lifornia 
as well as Hawaiian soils [some of the latter contain 
as'muoh as 39 2 per cent of ferric hydrate, corrospoud- 
iug to 27’4 per cent of metabic irou ) ooidirm the 
conclusion. A point of practical importance is that 
doirbtless in consequeirce of reductive process s, soils 
very rich in ferric hydrate suffer more promptly and 
severely from lack of drainage than similar soils of 
low iron percentage. 
Phosphoric Acid . — The convicition that )ias gradually 
established itself that the practical values of the 
several calcic phosphates are not nearly as different 
as was as first assumed, has materially increased the 
interest of pho.sphoric acid do'ermination iu soils, 
particularly when these are strongly calcareous, and, 
therefore, according to the well-known play of affinities, 
most of the phosphoric acid present will be m the 
form of a tri-calcic phosphate. Th -re is a good reason 
why less phosphoric acid iu a soil will suffice in 
soils riclr in lime, than iu those in which there is no 
base ready to dispute the possession as the acid with 
ferric oxide aiul alumina which render it relatively 
insoluble aud inert. The very miuu‘e amount of 
phosphates present in the best of soils will render the 
search of the roots for them very laborious, uuless it 
can be couveyod to them iu solution, iiuiepen ieutly of 
the acids the roots may exclu-’e. From the discussion 
of the upland loam soils of the Bouth- western , States, 
I have beeulel to consider '0-5 per cent of P2 05 as 
the least amount that can bo considered adequate for 
profitable production iu their case, and that the per- 
centage should ri-c to TO per cent to be satisfactory. 
Ilut iu calcareou.s, aud also in very suidy soils of 
great dcpili, less seems a good supply oven there, and 
in California (where in arly all soils arc caUareous) the 
percentage does not very oftsii excee I 10 per cent, 
even in soils of greet proseiit pro.luctivene.ss and 
durability. 
JInmvs . — Tbo determination of buinus by Uraiideau's 
melbod is of tbo highest iuterust, as against the 
extraction with potassic or sodio hydrates, sti 1 some- 
times rocoinmendeU. As tlie latter solvents do not 
discriminate between the crude, uuhumified vegetable 
matter and the active humus, it misses the main poiut 
of interest. What degree of uniformity can be pre- 
dicted of Ihe composition of humus in virgin soils, I 
have not had time to determine. Even the i>hysical 
properties of the ammouiacal solution obtained vary 
greatly yet, ss in any case humus must be considered 
the repository and store-house of the soils, uitrogon 
eupply,its proportion is of high interest. In the loam 
(oak) uplands of the cotton , States the percentage of 
humus seems to range usually between '70 aud ‘80 
per cent in the poorer sandy pine soils, '40 to '50 per 
cent in the black calcareous prairie soils froml'20to 
2-80 per cent. The determiuaiiona made there arc 
not, perhaps, sufficiently numerous to give fair 
averages. Iu California and iu the arid region generally 
the humus percentages as might be foreseen average 
somewhat lower ; lowest m light loam soils of the 
high mesas of Southern California, where '30 per cent 
aud even less has been found ; yet these soils produce 
well at first, when irrigated. Percentages of -dS to -Cl) 
of humus are common in good upland loam soils that 
are neither very calcareous nor highly ferruginous. 
The “ prairie,” or black adobe soils usually range 
from 1-20 to 1'80 per'eant, a very few as high as 3’00. 
On the whole, the highly ferruginous soils ara remark- 
able for large amounts of humus ; as iu the red soils 
of foot hills and of the Coast Bange. In these latter 
cases, however, the ammoniacal solution is usually 
quite light-colored, aud only becomes dark on evapor- 
ation, doubtless by oxidation. It is pointedly claimed 
in some of the fruit-growing regions of this State that 
a too clean cuUivation, entirely suppressiug the growth 
of weeds, aud thus affording no annuil addition of 
vegetable matter save from the fall of the leaves, tends 
to injure the production of the orchards. It is readily 
conceivable that the long, dry and hot season would 
tend to cause a very rapid oxidation of the humus iu 
the soil well tilled a'mouuting to deprivation when only 
a very little is originally present. From experience 
had iu greeu-mauuriug, it seems that half of 1 per cent 
(’50) is the minimum of humus desirable iu California, 
and that wlien loss is originally present an increase 
should be brought about as soou loossible. Iu Western 
Oregon aud on Puget Sound, where the summer raiu- 
fall is very heavy, humus loetceutages ranging from 
3 to b per cent are quite common. — Farmer's Review. 
; I ■■ ■ III I* 
CEYLON COCOA. 
By Du. A. J. II. CuESPi. 
One of the most carious features of modern com- 
mercial activity is that Nature is, as it were, com- 
pelled to improve on her own earlier efforts. Sup- 
posing that some much-prized plant is found to do 
well iu a pariieular region with a climate of givt u 
warmth aud under certain recognised conditions : iha 
next thing is to find out a region where these cou- 
ditioiis ace still better, and to introduce the plant 
there. This seems to have been doo^ with the cacao 
tree in Ceylon, and cocoa of superlative excellence 
has for many years been manufactured from cacao 
beaus imported from that beautiful island. Seme 
braud s of Ceylon cocoa have been recently commanding 
very high prices; this shows what a magnificent field 
exists iu Ceylon for cocoa culture, aud that the quality 
of the cocoa from that island is far above the average 
of West Indian varieties. The principal peculiarity 
of the Ceylon braud is its delicate flavour aud rich 
aroma; although when prepared for use its price is 
not very high, aul quite within reach of most incomes. 
We confidently predict tliat as it becomes mo.-e 
gem rally known it will be sold in still larger quan- 
titio.s, aud so oprii up a fresh and most important 
branch of trade to British enterprise. 
Messrs. J. S. Fry aud sous, the well-known makers, 
whoso house was founded iu 1728, were not slow to 
recognise the peculiarly d. licioua flavour of OC3I0U 
cocoa, aud they have accordingly added another luxury 
to our household beverages iu the form of Gojloii 
chocolate, a speoiality that is being much appreciated 
by couuoisseurs, 
