" " " |9.74 |11,536|1144
Compost of vegetable mold |3.64 |20,608| 772
| | |
_Carbonic Acid in Atmosphere_ | D | E | F
|-----+------+----
|0.025|50,820| 14
--------------------------------------------------------+-----+------+----

From the above it is seen that in soils containing little decomposing
organic matters--as the forest sub-soils--the quantity of carbonic acid
is no greater than that contained in an equal bulk of the atmosphere. It
is greater in loamy and clayey soils; but is still small. In the
artichoke field (probably light soil not lately manured), and even in an
asparagus bed unmanured for one year, the amount of carbonic acid is not
greatly larger. In newly manured fields, and especially in a vegetable
compost, the quantity is vastly greater.

The organic matters which come from manures, or from the roots and other
residues of crops, are the source of the carbonic acid of the soil.
These matters continually waste in yielding this gas, and must be
supplied anew. Boussingault found that the rich soil of his kitchen
garden (near Strasburg) which had been heavily manured from the
barn-yard for many years, lost one-third of its carbon by exposure to
the air for three months (July, August and September,) being daily
watered. It originally contained 2.43 _per cent._ At the conclusion of
the experiment it contained but 1.60 _per cent._, having lost 0.83 _per
cent._

Peat and swamp-muck, when properly prepared, furnish carbonic acid in
large quantities during their slow oxidation in the soil.

3. _The Nitrogen of Peat, including Ammonia and Nitric Acid._

The sources of the nitrogen of plants, and the real cause of the value
of nitrogenous fertilizers, are topics that have excited more discussion
than any other points in Agricultural Chemistry. This is the result of
two circumstances. One is the obscurity in which some parts of the
subject have rested; the other is the immense practical and commercial
importance of this element, as a characteristic and essential ingredient
of the most precious fertilizers. It is a rule that the most valuable
manures, _commercially considered_, are those containing the most
nitrogen. Peruvian guano, s