--------------------------------------------------------+-----+------+---- _Designation and Condition of Soil._ | A | B | C --------------------------------------------------------+-----+------+---- Sandy subsoil of forest |0.24 | 4,326| 14 Loamy " " " |0.82 | 3,458| 28 Surface soil " " |0.86 | 5,768| 56 Clayey soil of artichoke field |0.66 |10,094| 71 Soil of asparagus bed, unmanured for one year |0.79 |10,948| 86 " " " " newly manured |1.54 |10,948| 172 Sandy soil, six days after manuring, and three | | | days of rain.|2.21 |11,536| 257 " " ten " " " " " | | | " " " |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._