Dec. 2, 1901.] THE TEOPIiAL AGRtCULTUEI'ST. 
381 
Nitrogen. 
It will have been noticed that in the above all 
reference to nitrogen has been omitted; 
It has been liaown for a long lime noiv that, 
whilst the mineral foods remain in the soil in much 
the same state of chemical combination, suffering 
within moderate periods of time but little chiinge, 
the nitrogen compounds of the soil are constantly 
undergoing very great changes. When first placed 
in the soil, either by accident, such as the remains 
of crops or leaves of trees, or by the agency of man 
in the form of farm manure, the nitrogen exisDs 
as a part of complex compounds, which ace classed 
principally under two heads, the albuminoid and 
amide bodies. 
It then becomes forthwith the food of a host of 
micro-organisms which resolve it gradually into sim- 
pler states of combination, such as a ammonia and 
nitrate''. Another class of organism is unfortunately 
also present, which may proceed a step further than 
many of us consider desirable, for it liberates the 
nitrogen altogether, a state in which this element 
is useless to moat plants. 
Now these changes in the condition of the nitrogen 
of the soil are coustantly going on, more vigorously 
at one time than at another, a moderate degree 
of warmth and a proper supply of moisture being 
among the most desirable conditions. Purthermoro, 
since some of these nitrogenous compounds are 
soluble in water, they are apt to be carried away by 
drainage water, which is not the case with either 
phosphates or potash. Thus it ia probable that no 
simple method will ever give us the answer corres- 
ponding to the one we have for valuing the supplies 
of the mineral foods. 
At present, at any rate, we can only determine 
the total amount of nitrogen in a soil, and judge 
from it whether it will repay us to supply manure. 
So far as Indian soils are concerned, I may say 
that, with few exceptions, they uniformly contain 
very low proportions of nitrogen, and at the experi- 
mental farms we have found that nitrogenous, 
manures have given greatly increased crops. In a 
series of experiments at the Cawnpore farm for 
instance, farm yard manure has produced, weight 
lor weight, a greater increase of wheat over a period 
of 15 years than it has done at either Rothamsted 
or Woburn in England.* 
NiTEOGENOus Foods. 
Chemists have, however, sought to answer another 
question about nitrcgenous food for plants. 
I have already indicated the states in which the 
nitrogen exists in the soil. There is in addition a 
very abundant supply of free nitrogen in the at- 
mosphere. It has therefore been a problem to deter- 
mine in which of these different states is the nit- 
rogen most useful to plants. 
As to the nitrogen of the atmosphere, I need not 
dwell at any length, more especially as I dealt fully 
with the subject in this room about 12 months ago. 
You are all probably aware, that it has been proved 
that elementary {i.e., uncombined nitrogen) is assi- 
milated by the plants of the papillionac^ and like- 
wise by some of the al^ffl, but among our farm crops, 
thoBB of other natural orders are dependent on a 
supply of combined nitrogen. 
Many years ago, experiments were mado by Cameron 
in England, and Hampe, Knop and Wagner in 
Germany, to test whether the higher plants were 
able to assimilate various forms of combined nitro- 
gen, and the result of the experiments was that the 
cereals were found to assimilate such nitrogenous 
compounds aa urea, hippurio acid, glyoocoU and 
guanidin, as well as nitrates and ammonia. 
Later, however, it became evident that these ex- 
periments were open to doubt, It became known 
* (An exhaustive examination of these experi* 
lenta is now in the Press.) 
that, nitroganous substances may be readily ohtnged 
by the vivrious micro-organisms into simpler com- 
pounds. It followed as quite possible, nay probable, 
that in Cameron's experiments, the complex nitro- 
genous compounds which he had added as manure, 
were, during the progress of the experiment, trans- 
formed by such organisms into simpler substances. 
In order to determine definitely whether such 
compounds \^ere useful to higher plants, the experi- 
ment must be conducted in the entire absence of 
such micro-organisms. 
The question has therefore baen lately taken up 
again, and with the result thiit, apparently none of 
these complex nitrogenous compounds are directly 
useful to fiighor pla-nts. Lyebyedyer found that 
barley could not feed on them in the absence of 
soil-organisms. And he practically proved this result 
by adding, in a second series of cultivations, a 
quantity of organisms from a soil, when his barley 
plants managed to make some headway. The growth 
was only moderate, for the plant had to wait until 
the micro-organisms had reduced the complex com- 
pounds to simplor forms. Finally he sluwed that 
nitrates, supplied in the absence of b-icteria, wei-e 
readily assimilated. Other woiker9 have been Maze, 
Lietz and Fagnonl, whose experiments generally 
confirm those of Lyebyedyer. These experiments are 
quite recent and will probably be repeated, but it 
is highly probable that the higher plants can only 
assimilate nitrates and ammonia, and that the more 
complex nitrogenous compounds must first be con- 
verted by the myriads of minute organisms, which 
inhabit the surface soils, into simpler compounds, 
before they can be useful to our crops 
Before passing on to the next chapter of this 
paper, I must not omit a vsry brief reference to 
the work on soils which Professor HilgArd, and 
those who are associated with him at the Dniver- 
sity of California, have undertaken. It consists of 
an exh^iustive examination of the inherent differences 
which exist between the soilj of the humid and the 
arid regions of America. TJufortuuately these in- 
vestigations cannot well be done justice to in any 
brief digest, and I must therefore, refer my hearers 
to Dr. Hilgard's original papers. Nor shall I detain- 
you with details of the invef^tigations which Hilgard 
and Lou;^hbridge in America, and I. here, have 
made on the salty land called usar in India, or 
"alkali lands" in America; excepting to say that, 
whilst working independently, we have arrived at 
corresponding conclusions. The result of those in- 
vestigations has gone to show that comparatively 
small amounts of these salts are sufficient to prevent 
the proper growth of crops ; that in some cases 
drainage may effect their removal, though in other 
cases the soils are in a less amenable state. Also 
that in some cases gypsum may be of service, iu 
other cases useless. — Indian Forester. 
{To he Continued.) 
^ — 
SUBSTITUTES FOR TEA, 
At the present time, when the important question 
of ho;v best to increase the consumption of tea with 
profit to producers and pleasure to consumers ia 
engaging so much attention, it mf.y be interesting 
to remind readers in this country that the cup that 
cheers does not everywhere contain the beverage 
with which we are all so familiar and which ia 
prepared from the leaves of a plant that is known 
scientificially as Theacliinensis. " Tea " is, in fact, 
an accepted term for a good many beverages that 
are no more tea than beer is, any infusion or de- 
coction made from the leaves, flowers or twio-s of 
edible plants and shrubs being conveniently described 
as tea. To begin with, it is doubtless commonly 
known that in many parts of youthern India, the 
Natives prepare a palatable and aromatic beverage 
Isonj the long leaves pt (he lemon grass. The leave^ 
