April 1, 1901.] THE TROPICAL AGRICULTURIST. 
665 
The organisms intimately connected with the 
fertility of the soil may conveniently be divided 
into two groups, namely, assimilating and destructive 
bacteria. 
Under the first group we would classify the nit- 
rifying and the nitrogen-fixing bacteria ; and in the 
second all species which cause putrefaction and 
decomposition may be included. 
The first group, as previously stated, includes 
nothing but beneficial species which are occupied 
either in building up nitrogenous compounds in 
the soil — the nitrifying species — or in fixing nitrogen 
from the atmosphere — the nitrogen-fixing bacteria — 
the latter of which, besides assisting plants to use 
this element, frequently also enrich the soil it- 
self. 
Important as is the numerous second group on 
account of the reducing power of its species, it in- 
cludes several that act disadvantageously in regard 
to agriculture. 
These objectionable species are the de-nitrifying 
organisms. By denitritication is understood the 
deoxidation nitrates and nitrites, which in each 
case involves a loss by either nitrogen or ammonia 
being given off. Their activity is perceptible by 
the pungent smell of ammonia rising from fresh 
stable manure, particularly from that of horses. 
Nitrogen being odourless, its loss cannot be per- 
ceived by the senses ; it nevertheless takes place to 
some extent during every process of decomposition 
where nitrogenous compounds are present. 
The Aims of Soil Bacteriology, 
It now remains to indicate the aims of Bacterio- 
logy in connection with agriculture. These are 
shortly as follows; — 
1 To encourage a definite multiplication of the 
nitrifying organisms found already in the fields, 
by adding substances that will enable them to 
retain their vitality and vigour after their activity 
ceases for the want of nitrogenous iraterial; and 
in case of their absence from a soil to transplant 
them thereto, if this can conveniently be done, by 
adding soil impregnated with the desired bacteria, 
2. To secure by the growth of plants favourable 
to nitrogen-fixiog organisms an enrichment of the 
soil by nitrogenous compounds ; and 
3. To counteract the sudden and excessive deve- 
lopment of the denitrifying organisms, in order to 
prevent loss of fertilising substances by means of 
these later.— /oitnia^ of the Department of Agricul- 
ture of Western Australia. 
ORANGE CULTIVATION IN CEYLON. 
With tea in its present parlous state, it behoves 
us to look about for some other product to assist 
the straggling planter and to help him to eke out 
the lean years. I have seen several references to 
orange growing in your columns, but do not think 
the importance of this culture has been sufficiently 
urged. 1 am of opinion that orange growing, and 
the growing of citrus fruits generally, will in many 
oases not only materially assist many estates suffer- 
ing from a depressed tea market, but, in suitable 
locations, lead to the up-rooting of tea to give place 
to a product infinitely more profitable. 
I have found, in course of conversation with 
planters and others in Ceylon, that they had not 
seriously looked on orange growing as an industry. 
For the information of all such I may quote from 
the Californian State Board of Trade returns for 
1898, which gives the value of a year's shipment of 
oranges and lettions out of that State as $7,226,356, 
or equivalent to E22,000,000. This is from one State 
alone, and is exclusive of the consumption of the 
local population numbering a million and a quarter. 
The annual importation of oranges into the United 
Kingdom exceeds 200,000,000, and this does not include 
any of the Californian crop already referred to» 
which gets no further than the Kortheru States, 
jwo hundred million oranges seema a large numbersi 
but it is not sis oranges per annum per head of 
the population, a consumption which cannot be re- 
garded as excessive. It has also to be remembered 
that in the event of importations being made into 
the United Kingdom from Ceylon, they would not 
come into competition with the pi-esent imports, as 
the Ceylon crop would strike the market when it 
was bare of the fruit, viz., from May to September 
right through the heat of summer, and just 
when this delicious thirst-quenching fruit would be 
most appreciated. On a recent visit' to the old coun- 
try I noted carefully the advent of the season's supply. 
The first oranges to appear were from Jamaica, 
and came in at the beginning of November, and sold 
at from 2d. to 3d. each, and these were followed at 
intervals up to January, by supplies from Sicily, 
Italy, &c., when they came in in large quantities, I 
was informed by a leading firm of London fruit- 
brokers that shipments received from May to October 
would undoubtedly command high prices. 
The Importations from Jamaica, which I have re- 
ferred to, are an example for Ceylon of a new industry, 
which dates its origin from the initiative action of 
Sir William Robinson, formerly Governor of that 
island, who in 1891 issued broadcast to the agricul- 
tural population a printed message urging the whole- 
sale planting of orange trees, pointing out the large 
trade that lay at their hands, aud offering nrizea 
for the best cultivated blocks under that fruit within 
a given time. The result of these measures is a 
steadily-increasing trade with the mother-country, 
What Jamaica has done Ceylon can do. 
That the best varieties of the orange will thrive in 
many parts of the island is now known, as small im- 
portations of grafted trees of good sorts have been 
made during the past few years, and their success 
has been snch as to justify their being planted on a 
commercial scale. 
Trees planted three years ago have already begun 
to bear, and it is here that the great advantage is 
seen of planting grafted trees instead of seedlings. 
Not only can the variety and excellence of the fruit 
produced be calculated on with perfect accuracy, if 
the young trees are procured from a reliable source, 
but, under proper cultivation and attention, the 
trees will begin to bear at from two to three years 
from planting, as compared with the eight or nine 
years one has to wait for fruit from a seedling tree 
in addition to which there is the uncertainty as to 
whether the fruit, when it does at last appear, will 
be an orange or a worthless throw-back of the sweet 
lime persuasion, 
Wickson, the leading Californian authority on 
orange culture, states in his official decription of the 
Washington navel orange, which is recognised as the 
finest variety in the world (and of which there are a 
few hundred specimens doing well in the island, some 
having already fruited and been proved true to tvpe) 
that it begins to bear as early as one year from the q'raft. 
The results of the few instances of lemon planting 
in the island have been even more satisfactory if 
possible, than with the orange, by reason of the tree 
being naturally a more rapid grower. Trees planted 
three years ago are now bearing well in the Dikoya 
District. Lemons are always in demand in the Lon« 
don market, and there are periods of the year when 
high prices are realized for them. The tree is hardier 
than the orange, and as it apparently does not require 
such richness of soil and general favourableness of 
conditions to develop the acid which is the charm 
of the lemon, as it does for the production of the 
sugar which is essential to a good orange, the lemon 
might profitably be grown along with the orange 
up the inferior portions of a block. 
As regards the profits to be made from orange and 
lemon culture, it would be easy to take the crop pro- 
duced by a given tree, multiply it by so many trees 
to the acre and calculate the value according to tha 
present market price. Were I to do that the result 
would be such as to make the mouths of many a 
truggling tea planter water with proeg^cts of richeq 
