Page 49

 A soil association is a geographic assemblage of soils. Any ac-
count of the soil associations (i.e., soilscapes, page 4; see Buol,
Hole, and McCracken, 1973) of a region must take the soil
series of that region into consideration. The list of kinds of soils
present in Wisconsin is still incomplete, for several reasons:
First, detailed observations have not been made in many areas,
particularly in northern counties; second, the process of classify-
ing the soils and correlating them with those of adjacent states is
still in progress; finally, changes in soils brought about by land
use have not been adequately observed, recorded, and eval-
uated. Even so, the current list of soil series is impressive, as rep-
resented in Part III. A soil association name, such as Tama,
Ashdale, Downs, and Muscatine silt loam (Al), tells what kinds
of soils are grouped in a repeating pattern in a particular land-
scape.
 In this discussion several soil terms that are somewhat
analogous to plant ecological terms are used.
                 Some Analogous Terms
Pertaining to plant ecology
botany (plant science)
phytosphere
vegetation of a region
flora of a region
sequence of plant
 communities
 down-slope
 xeric
I mesic
 hydric
 Pertaining to soil ecology
pedology (soil science)
pedosphere
soil continuum of a region
total list of soil series, types, and
 phases ('pedota) of a region
                    excessively
                     drained
soil association    well drained
(soilscape)         poorly or very
                     poorly
                     drained
 The pedosphere is the continuum of soils on the land portions
of the lithosphere. Within a particular region the soil continuum
is a mosaic of soilseapes in which the soil species, called soil
series, types, and phases, are present in certain proportions and
arrangements. We might coin a new collective term, pedota, for
the soil species of a region. Soil continuum and pedota differ
from each other in a quantitative way. The pedota is the total list
of soil species present, regardless of the numerical abundance of
each.' The soil continuum, on the other hand, has to do with
combinations of species present in a given region and with the
relative abundance of each species (Hole, 1953). For this pur-
pose, the common species are far more important than the rare
ones. The presence or absence of the latter may be of little sig-
nificance in the functioning of the landscape, though it may be
highly significant as a record of past environments. The basic
task of identifying and describing the soil series is arduous, and
is still in progress.
 1. One body of a rare species can contribute as much to the pedotal
list as thousands of bodies of a common species. In actual practice, soil
species are not listed in county soil survey reports unless they occupy
more than 500 to 1,000 acres. Therefore, considerable information
about unusual soils is not generally available. For example, in soil
association G25, in Sec. 16, T.37N., R.1OE. in Oneida County, a small
body of a red (2.5YR 4/4, moist) silt loam 50 cm thick over a sandy
loam fragipan resting on acid outwash sand was observed along Gude-
gast Creek. The soil map (Hole and Schmude, 1959) includes the area
in Peat-Au Gres soils, nearly level. The red soil remains unnamed and
is not described in the soil survey report.
                                   CHAPTER    6
                        Introduction to the
                           Soil Associations
                                 of Wisconsin
  Most soilscapes in Wisconsin include soils of both good and
poor natural drainage status, and were originally covered by a
vegetative sequence from a mesic or even xeric plant community
toahydric one, i.e., afen, wet meadow, orbog. Hence, soils that
are very different occur side by side on the land. Fig. 5-1 was de-
signed to indicate this. Crop production is known to vary from
one soil member of a soil association to another. Natural plant
communities are so rare, particularly in well-drained uplands,
that correlation of properties of soil profiles and native vegeta-
tion has been difficult. A serious attempt to do this was made in
the forests of the Menominee Indian lands (Milfred, Olson, and
Hole, 1967).
  The soil map (Plate 1) is cartographically generalized, but
with a legend that is detailed to the soil series level. This map
shows the major broad pedological features of the state and
serves as an introduction to detailed soil maps (see list, Appen-
dix 5) and to the actual soil bodies themselves.
  The 190 associations (Al through JiS) listed in the legend of
the soil map are distinctive, though in varying degrees. Several
examples will illustrate this. The level landscape of the Antigo
Flats in Langlade County is occupied by an association of soils,
the principal three of which are named Antigo silt loam, Brill silt
loam, and Onamia loam. This grouping is labeled F25 on the soil
map, not only in Langlade County, but wherever it occurs in
northern Wisconsin (Figs. 12-2, 13-3, 13-5). The Baraboo silt
loam and Skillet silt loam soil association (A 10) is extensive in
portions of the Baraboo Hills of Sauk County. The Horicon
Marsh in Dodge County is a large body of peat rimmed with wet
mineral soils. This soil association (slightly acid to alkaline sedge
and woody peat and muck soils; Pella, Poygan, and Brookston
silt loam and silty clay loam) is labeled 115 on the soil map. In
the drumlin field of Dodge County, well-drained soils of drum-
lins are associated in the landscape with linear bodies of wet soils
between the hills. This is soil association B13, Miami, Dodge,
and Pella silt loam association. The exact proportions of soils
present in each soil association are, with few exceptions, un-
known at present and therefore cannot be tabulated in this
report.
  Each soilscape has a characteristic fabric. Soilscape fabric
analysis is under study by the author and coworkers, and results
will be reported elsewhere. In brief, the study concerns soil body
patterns as they occur in loops, whirls, and stripes in the land-
scape.
  Many of the soilseapes, like the four examples just given, are
recognizable from the window of a vehicle during a trip across
                                                 49