70 
THE CULTIVATOR. 
Feb. 
for instance, that guano is valuable, and knows 
what are its effects upon his crops; but is he aware 
upon what, in the guano, those powerful effects de¬ 
pend? Could he, if an unknown substance equally 
rich in its composition were presented to him and 
the names of the elements which it contained given, 
say that it was worth much or worth any thing as a 
manure? I feel quite sure from my own experience, 
that the majority of our farmers, notwithstanding 
all that has been written on these smbjects, would 
have to answ'er this question in the negative. 
It is for such reasons that I am about to attempt 
a plain statement of some points connected with this 
important branch of agricultural knowledge, in the 
hope of making them clear and intelligible to at 
least a part of your readers. 
I have already montioned three great divisions— 
animal, vegetable, and mineral manures. In the 
tw T o first of these, are two classes of bodies—those 
which burn away by heat, called organic bodies, and 
the ash which remains after burning, consisting of 
mineral or inorganic bodies; of these last, the latter 
division of the three, the mineral manures, are en¬ 
tirely composed. The inorganic part in animal or 
vegetable manures, is usually quite small; as they 
are of course derived from the death and decay of 
plants and animals, it follows that in those forms of 
organised existence, the organic part also, as a ge¬ 
neral rule, predominates. Although then in these 
manures, the inorganic part is small, it is enough to 
supply the wants of the plants, by furnishing the 
materials for both classes of bodies which they con¬ 
tain, the combustible and the incombustible, the or¬ 
ganic and the inorganic. The mineral manures, on 
the contrary, can for the most part only nourish and 
increase the inorganic part of plants, and are conse¬ 
quently more limited in their application. 
It is ne:xt of importance to know what are the sub¬ 
stances thus furnished by the various classes of ma¬ 
nures. All the organic part of plants and animals, 
in the immense variety of their forms, shapes and si¬ 
zes, and consequently all of that part in the nume¬ 
rous manures which are employed by the husbandman, 
contain but four substances, named Carbon, Hydro¬ 
gen, Oxygen and Nitrogen. The first of these, 
Carbon, is a solid, of which charcoal, black lead, 
&c., are examples; the others are gases or kinds of 
air. This is one of the most striking facts connect¬ 
ed w r ith the advance of modern chemistry, that all 
forms of organised life should be ultimately resolved 
into these four bodies, excepting alone the small pro¬ 
portion of ash which most of them contain. This 
ash, the inorganic or mineral part of plants, animals 
and manures, consists of more numerous substances; 
they form, however, not by any means a long list. 
They are potash, soda, lime, magnesia, iron, silica, 
chlorine, sulphuric acid and phosphoric acid, nine in 
all. There are one or two others occasionally inclu¬ 
ded, but they do not seem to be of much importance 
to to our cultivated crops. 
I mention these simply for th8 purpose of giving 
their names; to describe the appearance and proper¬ 
ties of each would be foreign to my present purpose. 
Any farmer who wishes to become acquainted with 
them personally, can easily find directions w T hich will 
enable him to accomplish his desire. Their names 
and numbers being now given, in my further re¬ 
marks reference may be made to them without cau¬ 
sing the reader to feel as if he were on entirely un¬ 
known ground, or among utter strangers. 
From the connection in which the organic and the 
inorganic parts of plants, animals and manures 
were placed, the nature of the relation between the 
two former and the latter, will now be plainly seen ; 
the farmer will understand that to his knowledge of 
the fact that manures are the food of plants, he has 
added the names of the substances which constitute 
that food. 
This is an important step gained, but it only 
plunges us into fresh difficulties as we come to exa¬ 
mine the diverse effects of the various fertilizing 
substances which are considered valuable, and which 
indeed experience has proved beyond a question to 
be so. In looking over accounts of results obtained 
by using different manures of known composition, 
the farmer perceives great variation in their appa¬ 
rent effects. A small quantity of guano for instance, 
is more powerful in enriching the soil and hastening 
the growth of plants, than a whole load of ordinary 
manure, weighing probably fifty times as much 
This is a very striking difference, and leads to a 
comparison as to the composition of the two manures. 
It is found first, that the barn-yard manure contains 
a largo quantity of water which of course deterio¬ 
rates so much from its value; second, on examina¬ 
tion of the dried residue in each, it is found to con¬ 
sist of the same substances. These are not, how¬ 
ever, in the same proportions. In the guano, we 
find that ammonia and phosphates are the leading 
ingredients; in the barn-yard manure, carbon and si¬ 
lica. 
Here is a tangible difference, but the most doubt¬ 
ful feature in the case to the farmer, has yet to be 
explained. He points to the analyses of plants and 
says, “ silica in the ash and carbon in the organic 
parts are most prominent substances, and why are 
they not equally valuable with the others that are less 
in quantity?” Ammonia owes its value to the ni¬ 
trogen which it contains, and phosphates theirs to 
their phosphoric acid, they being combinations of 
that acid with lime, magnesia, iron, See. Nitrogen 
and phosphoric acid then are added most largely by 
guano, silica and carbon by farm-yard manure. What 
is the cause of so wide a variation in effect upon all 
crops? Why are the two first worth more than the 
two last, since plants do not contain so much of them? 
To this I reply at onco that they are not in them¬ 
selves more valuable or more necessary, and shall 
proceed to show that their superior importance is 
owing to circumstances alone. 
First, as to phosphoric acid. In the straw and 
husk of grain we find little of this substance, but in 
the grain itself fully half of the ash is composed of 
it; it is present in the grain because that is the na¬ 
tural food of the animal in which must be contained 
the material for building the bones, the frame-work 
of the animal body, these being made up chiefly from 
phosphate of lime. We find the same thing to be 
true of nitrogen; in the straw and all those parts of 
plants that are not of much value as food, there is 
little of it, but in the grain and all food considered 
particularly nutritious, there are certain substances 
quite rich in nitrogen. This body constitutes a 
principal part of animal flesh, and thus food which 
contains much of it is remarkably nutritious becauso 
it supplies this material toward the increase of the 
body. Ammonia is important in manures, because 
it is a chief means of furnishing nitrogen to the 
plant. 
This brings us to the point which I wish to im¬ 
press. When we examine a soil, we find that its 
fertility or barrenness, depends on the presence or 
absence of the various substances named above. If 
one of them is wanting, the capacity of the soil for 
bearing good crops is greatly diminished. The most 
likely deficiency in long cultivated soils, is in the 
phosphates, and in bodies containing nitrogen . In 
new soils, these two classes are as a general rule 
