T H E N4 A.(4 A Z 1 N E 
OF 
TF>e 5CR00L OF SGRICULTURG, 
COLOMBO. 
Added as a Sup^dement monthli/ to the TliOPIGAL AGRICULTURIST,” 
Tlie following pages include the contents of the Magazine of the School of 
Agriculture for August : — 
PLANT FOOD AND ANIMAL FOOD. 
T is a common error to suppose 
that chemical analysis, and this 
alone, is necessary for finding out 
the nature of manures to be 
applied to crops, and the nature 
of foods to he supplied to aniimils. It was one of 
the unfortunate results of the teaching of Liebig 
that agriculturists came to believe that when the 
composition of the ash of plants was ascertained, 
farming would be reduced to a simple equation : — 
Given the elements of the soil and the composition 
of the plant, required the manure. They now know, 
however, that there are other considerations to 
be taken into account in deciding what manure 
should be supplied to a crop. The legumiuosre^ 
for instance, are found by analysis to be rich in 
nitrogen, and yet nitrogenous manures produce 
hut little efiect on leguminous crops: while 
tliough the cereals are most benefited by nitro- 
genous manures, they contain less nitrogen than 
roots and leguminous crops. Thus the composi- 
tion of the crop is not a sufficient guide to the 
character of the manure to be applied, even 
when the analysis of the soil on which it is 
grown is known. We require to know in addi- 
tion the power of the crop to assimilate tlie 
ingredients of ])lant food. 
In the same manner there are other conside- 
rations besides the chemical composition of the 
food su])plied to animals whicli mu.st influence 
our .selection of Food-stufl's. .lust as Ihe food 
ingredients of the plant may be j)resent in the 
soil in a condition in which they cannot be 
made use of, so also may the nitrogenous and 
non-nitrogenous parts of food exist in a form 
in which little nutriment is derived from them 
liy animals. For a long time all the nitrogen 
in the food of animals was supposed to be in 
the form of albuminoids ; but during the last 
few years it has been shown that a part of the 
nitrogen of vegetable foods exists not as albu- 
minoids, but as amides, and, in some cases, as 
nitrates. Thus it is quite possible that a food 
which was supposed to contain more albiiminoids 
(reckoning all the nitrogen as albuminoids) than 
another, may turn out, when the true albumi- 
noids only are taken into accoimt, to be inferior 
in value. Having ascertained the amount of true 
albuminoids, we are able to find the “ albumin- 
oid ratio,’’’ that is the proportion of digestible 
albuminoids to digestible non-albuminoids in food. 
For the best feeding results a certain proportion 
between these two must be observed : and it 
will be readily admitted that to supply animals 
with an unlimited amount of food without con- 
sidering the ratio of albuminoid matter to carbo- 
hydrates will not give us the best feeding 
results. The results of the analyses of vegeta- 
ble foods are generally given under the heads 
of water, nitrogenous substances (the albuminoids 
being reckoned separately), fat, soluble carbo- 
hydrates, fibre, and ash. In calculating the 
albuminoid ratio the fat is reduced to its equi- 
valent in starch hy multiplying by 2'o, and the 
result is added to the soiubie carbo-hydrates. 
The most imjjortant consideration in the" matter 
of feeding, hoAvever, is the digestibility of foods, 
which can only be ascertained by experiment ; 
and the general method adopted' is to supply 
an animal with weighed quantities of footl, the 
composition of which is known, collect and 
weigh the solid excrements and analyse them, 
and thus obtain almost tlie e.xact amount of 
