SELECTION OF PEAT LANDS FOR DIFFERENT USES 9 
« 
Fibrous layers of peat, shown in Plates 4 arid 5, are porous and 
more or less resistant; they stand up well in vertical- walled ditches 
and excavations, yielding slowly to frost action and decomposition. 
In the profile series of Plate 1 the layers are designated by the digit 
2. Plate 4, A, shows an air-dry sample of rusty brown fibrous 
hypnum peat, spongy and poorly decomposed. The outline of the 
plant remains is fairly clear and distinct, and the material contains 
scarcely any of the altered nonfibrous fraction of organic material 
which is characteristic of more advanced stages of disintegration. 
Plate 4, B, represents a dark-brown hypnum peat, partly disintegrated, 
in which the individual plants and their structure are more or less 
discernible to the eye. Plate 4, C, illustrates the side view of an air- 
dry sample of hypnum peat, reddish to yellowish brown, partly fibrous, 
resting on a layer of fine-textured sedimentary peat with shells. 
Distinguishing characteristics of sphagnum peat are shown in Plate 4, 
D. The material is fight brown, coarsely fibrous, spongy, and most of 
the plant remains are very well preserved. In Plate 4, E, the character- 
istic structure of the sphagnum mosses is still recognizable, and in Plate 
4, F, the brown air-dry sphagnum peat shows a crumbly texture, owing 
to the more advanced stage of disintegration. The proportion of the 
undecomposed " crude-fiber" fraction of organic matter is still rather 
high in this material. 
Varieties of sedge and reed peat are shown in Plate 5: A, Sedge 
muck from a dark-brown, disintegrating fibrous sedge peat, after one 
year of cultivation under natural field conditions; B, typical sample 
of the dark-brown, finely fibrous, felty sedge peats, showing radi- 
cellate structure; G, an air-dry, brown, coarsely fibrous, spongy sedge 
peat, poorly decomposed, representing the underground stems and 
roots of sedges which spread over a lake or pond after having floated 
as a mat of varying thickness on the surface of the water; D, a 
blackish brown, well-disintegrated reed peat, granular after five 
years under cultivation. It will be noted that the proportion of the 
altered nonfibrous fraction of organic material is very large in this 
reed muck. The underground untilled portion of a reed peat is 
shown in Plate 5, E. This material represents a dark-brown, partly 
fibrous reed peat in which the plant remains are more or less clearly 
discernible. Fungal hyphse are often present, but they form an unim- 
portant proportion of the mass. It is not uncommon, however, to 
find a still more fibrous material at lower depths below the surface. 
Plate 5, F, represents a yellow-brown, coarsely fibrous reed peat, 
rather spongy and very poorly decomposed. The material is easily 
identified by the characteristic structure of the nodes and its wavy 
internodes. 
It is not generally understood that fibrous layers of peat, whether 
derived from mosses (pi. 4, A and D) or from the roots and under- 
ground stems of sedges and reeds (pi. 5, C and F), should be subjected 
to maceration or to the alternation of moisture and moderate dn^ing. 
Such layers must be changed to muck and humus stages by means 
of aeration, freezing, and the activity of microorganisms. Variations 
in the content of finely fibrous, felty, or carbonized material and 
mixtures of fibrous with sedimentary peat tend to hasten decay, 
whereby favorable biochemical reactions for plant growth are created . 
A very serious problem is presented by the blowing of the dustlike 
surface muck derived from decomposing mixed and fibrous types of 
95731—26 2 
