Soil Survey of McHenry County, Illinois Part I - Soil Data Mart

McHenry County, Illinois—Part II 175
Crops other than those shown in the table are
grown in the survey area, but estimated yields are not
listed because the acreage of such crops is small. The
local office of the Natural Resources Conservation
Service or of the Cooperative Extension Service can
provide information about the management and
productivity of the soils for those crops.
Pasture and Hayland Interpretations
Under good management, proper grazing is
essential for the production of high-quality forage,
stand survival, and erosion control. Proper grazing
helps plants to maintain sufficient and generally
vigorous top growth during the growing season. Brush
control is essential in many areas, and weed control
generally is needed. Rotation grazing and renovation
also are important management practices.
Yield estimates are often provided in animal unit
months (AUM), or the amount of forage or feed
required to feed one animal unit (one cow, one horse,
one mule, five sheep, or five goats) for 30 days.
The local office of the Natural Resources
Conservation Service or of the Cooperative Extension
Service can provide information about forage yields
other than those shown in table 7.
Land Capability Classification
Land capability classification shows, in a general
way, the suitability of soils for most kinds of field crops.
Crops that require special management are excluded.
The soils are grouped according to their limitations for
field crops, the risk of damage if they are used for
crops, and the way they respond to management. The
criteria used in grouping the soils do not take into
account major and generally expensive landshaping
that would change slope, depth, or other
characteristics of the soils, nor do they include
possible but unlikely major reclamation projects.
Capability classification is not a substitute for
interpretations designed to show suitability and
limitations of groups of soils for forestland or for
engineering purposes.
In the capability system, soils generally are grouped
at three levels—capability class, subclass, and unit
(USDA, 1961). These categories indicate the degree
and kinds of limitations affecting mechanized farming
systems that produce the more commonly grown field
crops, such as corn, soybeans, small grain, and hay.
Only class and subclass are used in this survey.
Capability classes, the broadest groups, are
designated by Roman numerals I through VIII. The
numerals indicate progressively greater limitations and
narrower choices for practical use.
If properly managed, soils in classes I, II, III, and IV
are suitable for the mechanized production of
commonly grown field crops and for pasture and
forestland. The degree of the soil limitations affecting
the production of cultivated crops increases
progressively from class I to class IV. The limitations
can affect levels of production and the risk of
permanent soil deterioration caused by erosion and
other factors.
Soils in classes V, VI, and VII are generally not
suited to the mechanized production of commonly
grown field crops without special management, but
they are suitable for plants that provide a permanent
cover, such as grasses and trees. The severity of the
soil limitations affecting crops increases progressively
from class V to class VII. The local office of the
Cooperative Extension Service or the Natural
Resources Conservation Service can provide
guidance on the use of these soils as cropland.
Areas in class VIII are generally not suitable for
crops, pasture, or forestland without a level of
management that is impractical. These areas may
have potential for other uses, such as recreational
facilities and wildlife habitat.
Capability subclasses identify the dominant kind of
limitation in the class. They are designated by adding
a small letter, e, w, s, or c, to the class numeral, for
example, IIe. The letter e shows that the main hazard
is the risk of erosion unless a close-growing plant
cover is maintained; w shows that water in or on the
soil interferes with plant growth or cultivation (in some
soils the wetness can be partly corrected by artificial
drainage); s shows that the soil is limited mainly
because it is shallow, droughty, or stony; and c, used
in only some parts of the United States, shows that the
chief limitation is climate that is very cold or very dry.
There are no subclasses in class I because the
soils of this class have few limitations. Class V
contains only the subclasses indicated by w, s, or c
because the soils in class V are subject to little or no
erosion. They have other limitations that restrict their
use mainly to pasture, forestland, wildlife habitat, or
recreation.
The capability classification of map units in the
survey area is given in table 7.
Pasture Limitations and Hazards
Growing legumes, cool-season grasses, and warmseason
grasses that are suited to the soils and the
climate of the area helps to maintain a productive
stand of pasture.