Peat and its Uses as Fertilizer and Fuel. Samuel W. Johnson
and when dried forms somewhat elastic masses. Grass peat, when taken a little below the surface, is commonly destitute of fibres; when wet, is earthy in its look, and dries to dense hard lumps.
Where mosses and grasses have grown together simultaneously in the same swamp, the peat is modified in its characters accordingly. Where, as may happen, grass succeeds moss, or moss succeeds grass, the different layers reveal their origin by their color and texture. At considerable depths, however, where the peat is very old, these differences nearly or entirely disappear.
The geological character of a country is not without influence on the kind of peat. It is only in regions where the rocks are granitic or silicious, where, at least, the surface waters are free or nearly free from lime, that mosses make the bulk of the peat.
In limestone districts, peat is chiefly formed from grasses and sedges.
This is due to the fact that mosses (sphagnums) need little lime for their growth, while the grasses require much; aquatic grasses cannot, therefore, thrive in pure waters, and in waters containing the requisite proportion of lime, grasses and sedges choke out the moss.
The accidental admixtures of soil often greatly affect the appearance and value of a peat, but on the whole it would appear that its quality is most influenced by the degree of decomposition it has been subjected to.
In meadows and marshes, overflowed by the ocean tides, we have salt-peat, formed from Sea-weeds (Algæ,) Salt-wort (Salicornia,) and a great variety of marine or strand-plants. In its upper portions, salt-peat is coarsely fibrous from the grass roots, and dark-brown in color. At sufficient depth it is black and destitute of fibres.
The fact that peat is fibrous in texture shows that it is of comparatively recent formation, or that the decomposition has been arrested before reaching its later stages. Fibrous peat is found near the surface, and as we dig down into a very deep bed we find almost invariably that the fibrous structure becomes less and less evident until at a certain depth it entirely disappears.
It is not depth simply, but age or advancement in decomposition, which determines these differences of texture.
The "ripest," most perfectly formed peat, that in which the peaty decomposition has reached its last stage—which, in Germany, is termed pitchy-peat or fat peat, (Pechtorf, Specktorf)—is dark-brown or black in color, and comparatively heavy and dense. When moist, it is firm, sticky and coherent almost like clay, may be cut and moulded to any shape. Dried, it becomes hard, and on a cut or burnished surface takes a luster like wax or pitch.
In Holland, West Friesland, Holstein, Denmark and Pomerania, a so-called mud-peat (Schlammtorf, also Baggertorf and Streichtorf,) is "fished up" from the bottoms of ponds, as a black mud or paste, which, on drying, becomes hard and dense like the pitchy-peat.
The two varieties of peat last named are those which are most prized as fuel in Europe.
Vitriol peat is peat of any kind impregnated with sulphate of iron (copperas,) and sulphate of alumina, (the astringent ingredient of alum.)
Swamp Muck.—In New England, the vegetable remains occurring in swamps, etc., are commonly called Muck. In proper English usage, muck is a general term for manure of any sort, and has no special application to the contents of bogs. With us, however, this meaning appears to be quite obsolete, though in our agricultural literature—formerly, more than now, it must be admitted—the word as applied to the subject of our treatise, has been qualified as Swamp Muck.
In Germany, peat of whatever character, is designated by the single word Torf; in France it is Tourbe, and of the same origin is the word Turf, applied to it in Great Britain. With us turf appears never to have had this signification.
Peat, no doubt, is a correct name for the substance which results from the decomposition of vegetable matters under or saturated with water, whatever its appearance or properties. There is, however, with us, an inclination to apply this word particularly to those purer and more compact sorts which are adapted for fuel, while to the lighter, less decomposed or more weathered kinds, and to those which are considerably intermixed with soil or silt, the term muck or swamp muck is given. These distinctions are not, indeed, always observed, and, in fact, so great is the range of variation in the quality of the substance, that it would be impossible to draw a line where muck leaves off and peat begins. Notwithstanding, a rough distinction is better than none, and we shall therefore employ the two terms when any greater clearness of meaning can be thereby conveyed.
It happens, that in New England, the number of small shallow swales, that contain unripe or impure peat, is much greater than that of large and deep bogs. Their contents are therefore more of the "mucky" than of the "peaty" order, and this may partly account for New England usage in regard to these old English words.
By the term muck, some farmers understand leaf-mold (decayed leaves), especially that which collects in low and wet places. When the deposit is deep and saturated with water, it may have all the essential characters of peat. Ripe peat, from such a source is, however, so far as the writer is informed, unknown to any extent in this country. We might distinguish as leaf-muck the leaves which have decomposed under or saturated with water, retaining the well established term leaf-mold to designate the dry or drier covering of the soil in a dense forest of deciduous trees.
Salt-mud.—In the marshes, bays, and estuaries along the sea-shore, accumulate large quantities of fine silt, brought down by rivers or deposited from the sea-water, which are more or less mixed with finely divided peat or partly decomposed vegetable matters, derived largely from Sea-weed, and in many cases also with animal remains (mussels and other shell-fish, crabs, and myriads of minute organisms.) This black mud has great value as a fertilizer.
4. The Chemical Characters and Composition of Peat.
The process of burning, demonstrates that peat consists of two kinds of substance; one of which, the larger portion, is combustible, and is organic or vegetable matter; the other, smaller portion, remaining indestructible by fire is inorganic matter or ash. We shall consider these separately.
a. The organic or combustible part of peat varies considerably in its proximate composition. It is in fact an indefinite mixture of several or perhaps of many compound bodies, whose precise nature is little known. These bodies have received the collective names Humus and Geine. We shall employ the term humus to designate this mixture, whether occurring in peat, swamp-muck, salt-mud, in composts, or in the arable soil. Its chemical characters are much the same, whatever its appearance or mode of occurrence; and this is to be expected since it is always formed from the same materials and under essentially similar conditions.
Resinous and Bituminous matters.—If dry pulverized peat be agitated and warmed for a short time with alcohol, there is usually extracted a small amount of resinous and sometimes of bituminous matters, which are of no account in the agricultural applications of peat, but have a bearing on its value as fuel.
Ulmic and Humic acids.—On boiling what remains from the treatment with alcohol, with a weak solution of carbonate of soda (sal-soda), we obtain a yellowish-brown or black liquid. This liquid contains certain acid ingredients of the peat which become soluble by entering into chemical combination with soda.
On adding to the solution strong vinegar, or any other strong acid, there separates a bulky brown or black substance, which, after a time, subsides to the bottom of the vessel as a precipitate, to use a chemical term, leaving the liquid of a more or less yellow tinge. This deposit, if obtained from light brown peat, is ulmic acid; if from black peat, it is humic acid. These acids, when in the precipitated state, are insoluble in vinegar; but when this is washed away, they are considerably soluble in water. They are, in fact, modified by the action of the soda, so as to acquire much greater solubility in water than they otherwise possess. On drying the bulky bodies thus obtained, brown or black lustrous masses result, which have much the appearance of coal.
Ulmin and Humin.—After