UNITED STATES DEPARTMENT OF AGRICULTURE

DEPARTMENT BULLETIN No. 1419

Washington, D. C.

October, 1926

FACTORS AND PROBLEMS IN THE SELECTION OF PEAT LANDS. FOR

DIFFERENT USES

By ALFRED P. DACHNOWSKI, Associate Physiologist, Office of Soil Bacteriology, Bureau of Plant Industry

It is estimated that approximately 79,000,000 of the 113,537,000 acres of wet land in the United States are of potential economic importance. The question whether the utilization of these peat lands is economically practicable is of special interest in the States bordering the Great Lakes and those on the Gulf Coastal Plain, and the rest of the country, concerned with the growing needs of a growing population, is showing an increasing interest in the problem.

For an economically sound solution of the problem, agriculture and other industry must have a fuller knowledge of the nature of the peat lands and must deal with them according to that knowledge. It is essential that the problem be seen as a whole, or at least broadly, sothat the relationship among the various conditions and factors which must be coordinated and controlled in the future utilization of the peat lands may be understood.

Just what type of peat area shall be used is often more important than the choice of the surface material. It is equally clear that in any particular case the selection depends upon several factors, among: which the general economic considerations taken intccount are frequently only the more obvious ones. On the oth hand, the profile features of the peat area, the stage of disintegration of the

The acreage of peat land was much larger at an earlier time, but with the settlement of the States many extensive areas of shallow peat that were long under cultivation have now disappeared. Only blackcolored mineral soils with a high humus content remain to-day to suggest the former locations of such.

areas.

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different layers, and the condition of the water supply and of the mineral substratum are seldom examined. For this reason there has always been a certain element of hazard and doubt in the economic development of peat resources.

Experience in the United States appears on the whole to be in accord with that reported for Europe. From many peat lands under cultivation the returns in vegetables, forage crops, or small grains have been disappointing, although for unknown reasons on occasional fields excellent crops have been raised. Some peat lands are easily tilled, increase the quality of timber produced, supply a material which yields a satisfactory artificial manure upon composting, or carry a roadbed designed for heavy traffic, while other peat areas are not giving promising results. To remove the element of doubt, or at least to reduce it, is the purpose of this bulletin. Briefly, the object is to formulate a basis for a more definite selection and also for safer and more economic procedure in the work of improving, for different uses, peat lands which have been abandoned in various sections of the country.

EXAMINATION OF PEAT LANDS

In order to determine the class to which any peat-land unit belongs a systematic examination of the fundamental factors is required. Undue stress has often been laid on the color of the peat material, the acid reaction, or the native surface vegetation, as the factors which indicate the type of land to be chosen for development. In many instances, farmers have failed because the peat area did not produce according to expectations based on surface conditions. The observed failures are now well understood to be due to inexperience as to the widely varying essential differences between peat lands, each case requiring more or less special examination; and, in consequence, efforts are now being directed toward working out a more dynamic and geographic basis for correlating the possibilities and limitations of peat lands. The aim is to prevent the difficulties at their source, rather than to adopt doubtful corrective measures. It is therefore of considerable importance to supplement in various ways the general observations upon peat and muck, with more detailed descriptions of the whole profile and of certain outstanding factors, such as the sources of ground water and mineral subsoil. Upon information concerning these factors an intelligent estimate of peat areas may be based.

A field method to establish a natural classification of peat lands has now been used over a section of this country large enough to lead to wide general views. Directions for a uniform method to be followed have been published under the title "The Stratigraphic Study of Peat Deposits" (11). As a supplementary aid to this subject a series of investigations limited to restricted regional areas has been made (9, 14, 15), and others are in progress. These studies are not without interest to those who are working on the nomenclature and mapping of peat lands, on comparative researches in general soils science, and in geology and ecology.

'Serial numbers (italic) in parentheses refer to "Literature cited," at the end of this bulletin.

In selecting a peat-land area, two lines of procedure demand careful attention, and they should be followed as far as possible for the particular area under consideration. In the preliminary observations as to the quality of the peat land and its layout a survey is made which covers the points outlined on the tally sheet in the publication cited above (11). If the reconnaissance study indicates that the area is probably suitable for the intended use to be made of it-e. g., systematic field experiments and research, settlement, reforestation, or production of stable litter and peat composts-the final investigation should be made with great care and more in detail.

If the area shows desirable qualities for the particular purposethe manufacture of peat litter, for example--the size of the tract should be outlined, its levels determined, and a map prepared showing acreage, boundaries, roads, elevations, outlet and fall of drainage waters, character of the vegetative cover, topographic features of the adjacent land, and the distance to main transportation facilities.

It is not generally recognized that careful scrutiny should be extended also to the structure of the entire peat area. In most cases of failure, the failure has been due to the fact that the importance

FIG. 1.-Profile of a peat-land area which developed under changing environmental conditions. The ground-water level became elevated with the gradual accumulation of plant remains. The different layers of peat not only reveal the nature of the former vegetation which yielded peat but also offer a basis for an analysis of the adverse external factors that tended to modify the conditions of plant growth.

of test holes was not understood or taken into account. Profile soundings indicate the nature of a peat area. For all specific purposes, samples of peat should be collected at each corner of sectional divisions which range from 100 to 300 feet or more in length. These samples should be obtained from different depths in order to ascertain more accurately any marked changes in pulpy, fibrous, or woody materials. This is important, not only in the comparison of peat layers but of peat areas. The amount of decomposition of each layer may be determined readily by the foodstuff method of analysis (12). This method permits a quantitative distinction between the different proportions of the undecomposed, resistant, crude-fiber fraction in a peat material and of the altered, nonfibrous fraction of organic material. These data will assist in drawing the isopachic lines that connect points at which the thickness of the several peat layers is measurable (figs. 1 and 2). A chart of this kind will indicate graphically the profile of the entire area; that is, the position, continuity,

and quality of the different types of peat. It will be of value, also, as a guide in mapping such land. The final map of the area should show clearly the distribution and boundary lines of the different type profiles. It should designate each unit by a symbol, letter, or special color, particularly the areas difficult from any cause to prepare for development, also the units recommended for suspension or proposed to be excluded. Charts and maps of this nature aid not only in making estimates of acreage and quantity of raw materials available for different uses, but they are useful in agricultural surveys and statistics. For practical application, the stratification of peat land may be applied to a number of different objectives, such as the classification of peat soils forming in the surface layers, the interpretation of results from similar areas of peat

FIG. 2.-Graphic presentation of stages in the formation of a peat deposit over a depression that contained an older body of standing water. Compare with Plate 2. Adapted from Dachnowski (6), arranged in reversed order

in different localities, or the comparison of European and American peat lands.

An index number has been used in field work to designate each type unit of peat-land profiles. It is especially useful for indicating the relative order and character of the chief layers of peat with respect to the mineral substratum. To visualize the structural framework correctly, peat-land profiles must be read upward (pl. 1). It should not be assumed, however, that this system of nomenclature is adequately descriptive, because the type profile of a unit area of peat may show variable characteristics of thickness, texture, color, and

stage of disintegration. The variations are very numerous and constantly changing, particularly in drained peat lands the surface layers of which are under cultivation. For types of peat land in which soilforming processes have become definitely established and horizons have appeared at different ranges of depth, the name of the locality

CARBONDALE PEAT-PROFILE 2-3

SPALDING PEAT - PROFILE 1-2-3

GREENWOOD PEAT - PROFILE 2

FIG. 3.-Specimen map of an area to show the distribution of types of peat land and the nomenclature employed to designate them. Each pattern represents a specific profile by which the characters of the peat area have been distinguished. (Courtesy of Michigan Land Economic Survey in cooperation with the Bureau of Plant Industry)

where these differences were first observed may be assigned to the index number of the type unit. A specimen map is given in Figure 3. Each pattern indicates the specific profile, shown in Plate 1, by which the character of the individual peat areas have been distinguished.