776 
THF TROPICAL AGRICULTURIST. 
[May i, 1890. 
Definition of Manuee. 
Manure is any substance added to the soil to increase 
its fertility by changing its compo ition, or by afford- 
ing an increased supply of plant-food. 
A complete or perfect manure is one that furnishes 
all the materials necessary for successful plant growth. 
The best example is to be found in farmyard dung. 
Animal excremeDts have been recognised from earli- 
est times as powerfully promoting vegetation, and 
increasing fruitfulness. Dung was the only manure 
known to the ancients, this being next followed, prob- 
ably, by the use of chalk, marl, and lime. 
On very poor soils it is necessary to make a full 
return of all the elements of plant-food removed by 
the crops ; but under the high-manuring frequently 
practised in garden culture, the contributions to the 
6O1I may be in excess of the removals, and the land 
may be increasing in fertility. In such cases a very 
partial manuring will suffice, a mere stimulant to en- 
courage extraordinary growth being all that is required. 
Effects of Manube upon the Soil. 
Before entering upon the action of the several 
ertilising ingredients oontained in manures, we may 
mention a few facts respecting their behaviour in the 
soil. Having already stated that potash, phosphoric 
acid, and nitrogen are by far the most important 
elements of plant-food, we will confine our remarks to 
those substances. The two former, phosphoric acid 
and potash, are perfectly soluble in water, but when 
added to a soil, they enter into combination with it, 
and thus become insoluble. 
For example, if a solution containing potash 01 
phosphoric acid be poured on a sufficiently large 
quantities of fertile soil, the water which filters through 
will be found, on testing, to be quite free from these 
ingredients. These retentive power of soils is of great 
practical importance in plant growth, especially in 
the restricted area of pot-culture ; if it were otherwise, 
the frequent waterings rendered necessary when limited 
quantities of soil are used would soon wash away all 
the soluble mineral salts of the soil, and the plants 
would starve for lack of nourishment. It has been 
conclusively proved, however, that if these manuring 
mineral substances are applied to soils, and for any 
reason the plants do not take them up, they remain 
there until they are wanted. It is far different with 
the third element of plant food which has be en men- 
tioned, namely, nitrogen. This substance exists in 
soils in the form of organic nitrogen, ammonia, and 
nitric acid. By the aotiou of a mmute "bacterium," 
present in all soils, the organic nitrogen and ammonia 
are oxidised, and their nitrogen converted into nitric 
acid. This operation only takes place in moist soils 
sufficiently porous to admit air, hence the immense 
advantages of thorough drainage. It is further nec- 
essary to successful nitrification that some base, such 
as chalk or lime, be present iu the soil. 
Of the three substances then, which constitute the 
principal food of plants, two are fixed by the soil, while 
one is liable to be washed away. Nitric acid is said, 
by Sir J. B. Lawes, to be in a constant state of move- 
ment in the land— at one time washed entirely from 
the surface by heavy rains, and rising again as evapor- 
ation takes place under a hot sun and drying winds. 
As dark-coloured soils absorb the greatest amount of 
heat from the sun's rays, the presence of a certain 
amount of humus derived from leaf-mould and other 
decaying vegetable matters, is advantageous both to 
warmth of soil, and to nitrification, and a very small 
dressing of readily available food added to such soils 
iu the form of nitrate of soda, ammonium salts, guano, 
rape-cake, or even liquid manure, will be found greatly 
to promote fertility, and to increase the stimuluting 
power of the soil. 
We shall hope to continue the subject on a future 
cc asion.— J. J. Wills.— Gardeners' Chronicle- 
-» 
COFFEE FROM PLANTATION TO CUP. 
The latest edition (15th) of this valuable book is 
just from the press. Additional statistical matter has 
been added, bringing down the movement of coffee 
and the exports from leading producing countries t Q 
:he present season. Great changes have taken place 
'n the coffee fields of the world. The supply from 
Brazil has increased greatly since the first edition of 
the book in 1881, when the average annual produc- 
tion was 229,149 tons for the period 1874 — 80, against, 
320,655 tons as the annual average export, 1881 — 89. 
Ceylon has almost disappeared as a source of supply. 
The exports of Sumatra, Java and Ceylon coffee are 
brought down to 1888 ; India to ](J86. One of the 
most interesting additions is the comparative table 
showing the average yearly price of different sorts of 
coffee from 1881 to 1888 inclusive ; it showing a range 
from 9'7 cents per pound for Fair to piime Rio to 
18.11 cents. This volume is invaluable to the dealer 
in food, for therein is found a description of how 
tea is jprepared, from notes made by the author during 
a trip around the world, also an account of visits 
to spice and tapioca plantations, with methods of 
preparation of those articles for market accurately 
described ; a visit to a citron and macaroni factory, a 
study of olives and olive oil in Spain; the wine dis- 
trics of France and Spain ; the salt mines of Cheshire ; 
a visit to a model English grocery store. No less 
interesting are notes of manners and customs in Japan, 
China, India, Egypt, France, Italy, Spain and other 
countries. Send for a circular giving contents or better 
yet, send two dollars and have the book sent by mail 
postage paid. — American Grocer. 
♦ 
ORANGES AND LEMONS. 
Those who are interested in the development of the 
resources of India are making great efforts, by means 
of selection, budding, and grafting of good sorts, to 
promote the cultivation of the various kinds of Orange 
in that country. With the severe competition of 
Southern Europe, California, Florida, the West Indies, 
the Azores, and New South Wales, it is doubtful 
whether any great results can be looked for in the way 
of exportation, but still the local demand necessitates 
ample supply. 
Mr. Woodrow, in his excellent Hhits on Gardening 
in India, tells us that the Orange succeeds admirably 
iu the dry parts of India, such as the Deccau, Mysore, 
and Central India, but that it does not thrive so well 
in low-lying moist districts. In making a plantation, 
the soil generally requires the addition of manure, such 
as street swet pings, or cow-dung laid on the surface, 
and then dug 18 inches deep. A crop of Potatos or 
Cabbages should be first taken off the ground, and the 
Orange trees then planted in straight lines, 10 feed 
apatt, among the other crops, and carefully watched 
during the first year to see that shoots do not come 
from below the graft ; should any do so, they must 
be rubbed off. The ground should be carefully worked 
•with a variety of crops needing irrigation during the 
first five years, while the Orange trees are gradually 
occupying the soil. When the trees are established, 
watering is diminished from March to Blay, when the 
soil is removed from around the roots, cow-dung being 
placed 3 inches deep in the trench, and covered up 
with fresh soil. The leaves fall off, and by the end 
of June the trees are covered with fresh leaves and 
flowers which ripen into fruit in the following February; 
A second flowering takes place in February and Blarch, 
the fruit from which ripens in December; but it is 
not advisable to let the same tree carry both crops, 
because it would interfere with the rest of the trees 
in the hot season. In the accompanying illustration 
from a photograph of Mr. Woodrow's No. 1 
represents the Shaddock, the largest of the Orange- 
like fruits; No. 2 is the Maloongee, with thick, warted 
skin; No. 5 is the Mozambique OraDge ; No. 6 is the 
Kowla Orange; No. 8 is the variety known as 
Khaguzee Limbog ; No. 9 is the looses-kinned Ointra 
or Suntra Orange, The other varieties though num- 
bered, are not named in Mr. Woodrow's book. 
Dr. Bonavia's promised monograph on the subject of 
the cultivated varieties of Orange is looked for with 
interest both by growers and by botanists,— Gardeners' 
Chronicle. 
