Page 510 - Moving the Earth_ The Workbook of Excavation
P. 510
PIT OPERATION
10.16 THE WORK
FIGURE 10.14 Building up a dump edge.
The prairie topsoils range from 8 inches to several feet in depth, may be brown or black, are
rich in both humus and minerals, and generally have an excellent texture.
Swamp topsoils, in any section, tend to be gray to black and may contain up to 85 percent
organic matter. Depths vary from a few inches to hundreds of feet. The richer deposits are not top-
soil as defined above, and will be discussed separately as peat.
In general, the salability of topsoil is determined more by appearance and texture than by the
ability to grow crops. The average topsoil buyer will seldom have soil tested, and tests are often
not as reliable as good judgment.
Topsoils with high percentages of clay or silt will be heavy, slow-draining, and inclined to
pack into hard lumps if disturbed when wet. Increase of humus content will soften the lumps.
Sandy or gravelly topsoil is loose in texture, drains readily, tends to dry out, and can be worked when
wet without caking. Most soils are of an intermediate structure, with variable draining and lumping.
