Factors of Soil Formation

The characteristics and properties of soil are a result of interactions over time of climate, living organisms, parent material, and landscape setting. The interaction of these factors generates complex physical, chemical, and biological processes. These processes, working over time, form definite layers, or horizons, in the soil.

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Climate

Climate influences soil formation by providing moisture and heat necessary for the weathering of parent material.  Water dissolves soluble materials and transfers nutrients to the lower parts of the soil.  Water also is needed to alter minerals to clay and transfer the clay to the lower layers.  Reaction, or pH, is largely influenced by climate.  Temperature affects the rate at which chemical reactions proceed.  Chemical reactions are slower at freezing than at a higher temperature.  Moisture and temperature affect the kinds of plants that grow on the soil.  Further organic matter accumulation and decomposition are influenced by moisture and temperature and by vegetation.  The effects of climate are modified by landscape setting and parent material.  Relatively large amounts of water are available for soil-forming processes in loess on the hill summits.  Little is available for plants in outwash on the valley trains, where much of the rainfall passes through the soil rapidly or where slopes are steep and water runs off quickly.  Climate may not remain constant throughout the development of the soil.  When drastic climate changes take place, soil forming processes most likely are altered and a new cycle of soil formation begins.  These climate changes can modify the time factor, as the age of the new soil development must be measured from the beginning of the climatic change.  Pepin County’s oldest landscapes have most likely seen several climatic changes and gone through several cycles of soil formation.  Wind can affect the development of soil by adding or removing fine particles of soil or organic matter.  It affects the moisture content of soils by influencing the rate of evaporation.  Climate can also have more localized effects.  For example, north and east facing slopes tend to be cooler and wetter than south  and west facing slopes. Depressional areas generally have cooler temperatures for a longer part of the year than summits and slopes of hills.

Pepin County has a cool, subhumid continental climate that favors the growth of trees and the formation of leached, acid soils with a thin, dark surface layer and a clay-enriched subsoil.  Present climatic differences within the county are too small to have resulted in major differences among the soils (Pepin County Soil Survey, 1997).

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Living Organisms

Living organisms, both plants and animals, affect soil formation by providing organic matter and transferring nutrients from the lower layers of the soil to the upper layers.  Plants influence the development of specific layers in the soil.  Vegetation influences the rate at which clay is transferred from the surface layer to the subsoil.  Plants and animals are related to other factors of soil formation, such as soil microclimate, parent material, and landscape setting, all of which collectively can determine the vegetation that grows on a soil.  At the time of settlement, forests covered most of Pepin County.  Mean annual precipitation is sufficient to grow trees on any of the soils; however, natural fires on some soils, such as Burkhardt soils, were common and helped to maintain the grass vegetation.  Native Americans who lived in the area and used these soils also used fire to maintain grass vegetation for ease of cultivation and for attracting game animals.  When protected from fire, these soils would follow a succession from grass and forbs to shrubs and finally to oak and pine forest.  Many soils on the broad valley trains of the Chippewa and Mississippi Rivers formed under tall grass prairie.  Areas between the prairies and the deciduous forests were called savannas.  The most striking feature of a prairie or savanna soil profile is the deep layer of organic matter accumulation—commonly 20 inches or more—and the somewhat darkened subsoil beneath.  Examples of this process are the thick, darkened A and AB horizons in the Finchford soils.  Prairie soils contain as much as 120 tons of organic matter per acre, compared with 70 tons per acre for forested soils.  A dense network of grass roots fills the profile, and most of the roots extend to a depth of 5 to 7 feet.  Forb roots of various shapes and lengths are interspersed; some penetrate to a depth of 20 feet.  In contrast to forest soils, where organic matter enters the soil from the surface and must be “plowed in” by earthworms, the organic matter deeply incorporated in prairie soils comes from the roots as they decay in place.  There is little input from litter at the surface.  Mound-building ants play an important role in the development of prairie soils.  They mix and aerate the soil as they build their tunnels and bring up nutrients and clay particles from the subsoil.  Their activities increase potassium and phosphorus levels in the topsoil.  When a prairie burns, nitrogen in the litter is oxidized and escapes from the prairie ecosystem. Nitrogen is returned to the system through nitrogenfixing bacteria in the root nodules of the plentiful prairie legumes and also through free-living nitrogen-fixing bacteria in the root zones of the prairie grasses.  It was the deep, rich prairie soils that eventually led to the nearly total conversion of tall grass prairie to agricultural crops (Packard and Mutel, 1997- Pepin County Soil Survey, 1997 ).

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Landscape Setting

The term landscape setting involves many facets.  Landscape setting indicates the broad location of the soil, such as hills, stream terraces, valley trains, or flood plains.  It also includes such characteristics as slope gradient, length, shape, uniformity, and aspect.  Landscape setting interrelates with climate by affecting runoff, which influences the amount of moisture available for the soil-forming processes and the removal of material by erosion.  Where runoff is very rapid, as on a steep nose slope, soil formation proceeds slowly.  Where runoff is slow, moisture may be abundant and soil formation proceeds at a faster rate.

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Parent Material

Parent material largely determines the physical and chemical properties of the soil, such as the capacity or ability of the soil to store water and nutrients for plants and the rate at which water can pass through the soil.  In Pepin County the soils formed in a wide variety of parent materials.  The soils on hills formed in loess, till, pedisediment, residuum, slope alluvium, and colluvium. The soils on valley trains formed dominantly in outwash with influence from alluvium, eolian sands, and organic materials.  The soils on stream terraces and flood plains formed in alluvium, slackwater deposits, and organic materials.

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Time

Time is required by climate, by plants, and by animals to form soil from the parent material.  Various soils have developed over periods of time ranging from a few years to many thousands of years.  The effect of time on soil is modified by all the other factors of soil formation.  The length of time in which soils are exposed at the surface is a modifying factor in soil formation. Soils can be no older than the age of the landscape surface upon which they form (Ruhe, 1975).  Not all the soils that form the surface of the landscape in Pepin County are the same age.  Landscapes erode back from their base level along streams and rivers to near the landscape summit.  The summit remains stable, little affected by erosive forces.  Where carbonates were present in the loess, they are typically deeply leached, and the soils are well developed and are relatively older than the soils downslope.  Downslope erosion over long periods of time has exposed fresh material.  The Lone Rock sandstone, for example, was exposed to weathering much later in time than the sediment overlying the Oneota dolostone formation several hundred feet higher on the landscape.  Urne soils formed in the Lone Rock Formation and are therefore younger than the Pepin soils that formed in the Oneota Formation.  Another factor modifying the effects of time is the rate at which parent material can be transformed into soils.  The small particles in loess, for example, weather relatively rapidly.  On the other hand, the larger particles in sandstone bedrock and in outwash on valley trains have a high proportion of slowly weatherable minerals, such as quartz, and are transformed very slowly into soils that have distinct layers (Pepin County Soil Survey, 1997).

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Soil Formation in Pepin County

Landscape setting modifies the time factor because rainfall runs rapidly off steep slopes.  Only a small amount of water enters the soil to form clay or leach carbonates and other soluble material.  Time is also modified by the effects of climate.  The soils of Pepin County formed in a climate that has varied during their formation.  During the early stages of soil formation, the climate was cold because of the proximity to glacial ice to the west, north, and east.  The early vegetation consisted of conifers followed briefly by oaks.  These species were short lived following the retreat of glacial ice northward.  The ensuing climate was warmer and drier and caused prairie plants to migrate eastward (Borchart, 1950).  About 4,000 to 5,000 years ago, the climate became cooler and more moist.  The big woods spread westward once again.  Aspect and topography were also factors in the expansion of the woodland.  Timber probably became established first on the sheltered north and east facing footslopes.  Trees may have even persisted here during the eastward migration of the prairie.  From these sheltered sites, timber spread out onto the silty and loamy terraces and upward onto the ridgetops.  Except for very steep south and west facing slopes along the Mississippi River and broad sandy areas along major rivers, the county at the time of settlement was covered with woodland. The character of the soils encroached upon by woodland changed in response to processes generated by the timber.  Forests produce little organic matter, most of which accumulates on the soil surface.  In contrast, the prairie soils build up large amounts of organic matter and form a thick dark surface layer.  The organic matter produced by the decay of leaves, limbs, and trunks is more acid than that produced by prairie vegetation.  The strong acids formed by water percolating through the surface litter and into the soil increased the mobility of clay, organic matter, and oxides and allowed them to be leached away or to accumulate in the subsoil.  The dark surface layer of soils that had previously formed under prairie vegetation gradually became thinner.  As clay and organic matter were removed, a thin bleached subsurface layer began to form just below the thinning surface layer. Clay and organic matter accumulated as thin waxy films on blocky peds in the subsoil and along cracks and pores formerly occupied by roots.  Fully developed forest soils, such as Seaton and Norden soils, have a black or very dark brown surface layer 2 to 4 inches thick; an ashy, grayish subsurface layer that is low in clay and organic matter and is 5 to 10 inches thick; and a subsoil with structural development and clay and organic matter on blocky structural surfaces.  When the land was cleared and cultivated, the thin surface and subsurface layers were commonly lost to erosion, and in many places tillage mixed the remaining upper layers with material from the upper part of the subsoil.  Some soils, such as Mt. Carroll soils, reflect the influence of both prairie and woodland because 36 Soil Survey of woodland did not persist long enough to alter the prairie soils completely.  Assuming all other factors are equal, soils form more rapidly in warmer, more humid conditions than the present climate affecting Pepin County.  Soils are frozen to some depth and the soil-forming process is drastically reduced for much of the year in a cool, subhumid continental climate (Pepin County Soil Survey, 1997).

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Contriubuted by Group 9: Kyle Oberg, Brian Toivonen, Todd Whalen

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Land Use Recommendations

The soils in the Hubbard Study Site are best suited for “low impact” activities such as recreation and pasture land.  The soil is easily eroded due to characteristics of seasonal water table changes, water erosion due to runoff along the gradual slope, and wind erosion due to the sandy texture.  The land areas with little to no slope could be used for many things, including low impact agriculture.  Zero-tillage and contour plowing are encouraged for sustainable use and the reduction of erosion.   The land areas with slope greater than 4 percent are very susceptible to erosion due to any disturbance.  The seasonal changes in water table discourage most uses, including construction and agriculture.  Many wetland plant and animal species can be found in the low lands of this site.  Low impact activities are also encouraged to reduce the human impacts on these species.

The following recommendations are for specific land uses.

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Contributed by Group 6: Sarah Buss, Travis Franz, Breck Johnson, Paul Kruschke

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There are several different vegetation covers that are suitable for soils of this site. Three types of habitat are important for open land wildlife: wild herbaceous plants, grain and seed crops, and grasses and legumes.  At the Hubbard site, three pits were classified as the Farrington soil, four pits were classified as the Finchford soil, and one pit was classified as the Hoopeston soil.  The soil pits range in slope from 0 to 3 percent.  Both soil type and slope are important factors in determining which vegetation regime is suitable on this site.

Both the Finchford and the Farrington soils are rated fair for wild herbaceous plants while the Hoopeston series is rated good for this type of habitat.  These native or naturally established plants can provide food and cover for wildlife, and are critical pheasant, quail, cottontail rabbit, and deer habitat.  This category includes plants such as bluestems, indiangrass, blueberry, goldenrod, lambsquarters, dandelions, blackberry, ragweed, wheatgrass, and nightshades. 

Grain and seed crops, such as corn, soybeans, wheat, oats, and barley, also provide important food and cover for geese, pheasants, quail, and small game.  The Hoopeston series is rated fair for grain and seed crops, but the Farrington and Finchford soils are rated poor for this habitat.  It is not recommended to use this type of habitat on the Hubbard site.

Grasses and legumes are important habitat components for geese, pheasants, quail, and cottontail rabbits.  This type of habitat also provides food and cover for many wildlife species.  Representative plant species include bromegrass, timothy, orchardgrass, clover, alfalfa, wheatgrass, and birdsfoot trefoil.  The Hubbard site has various ratings for this particular type of habitat.  Hoopeston soils are rated good for grasses and legumes, Farrington soils are rated fair, and Finchford soils are rated poor.

The wild herbaceous vegetation pattern seems to be the only habitat that works well with every soil type of the Hubbard site.  Although the other two habitats of grain and seed crops and grasses and legumes have good or fair ratings with some soils, there is a least one soil in each habitat types that rates poor.  Overall, this site is capable of supporting prairie vegetation and wildlife.  It is also suitable for trees and shrubs, but trees, shrubs, and herbaceous plants are important for different wildlife, and the vegetation that should be planted depends on the specific uses and wishes of the landowner.

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Contributed by: Trina Nowak, webmaster

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The U.S. Army Corp of Engineers defines a wetland as "...areas that are inundated or saturated by surface water or groundwater at frequency in duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions."  Currently the study site does not meet any of the qualifications for a wetland based on present vegetation, absence of soil mottling, and the absence of wetland wildlife.  The soil series determined for the study area are the Finchford, Hoopeston, and Farrington types.  Their properties are shown in the table below, with links to pictures of the physical surroundings of each type in our study area.

Both the Farrington and Hoopeston pits, which lie closer to the water table have a fair potential as a habitat for wetland plants based on large texture of surface layer, medium wetness, low acidity, low alkalinity and low slope.  Only a few of the possible plants are present, including cattails.  These have a poor potential as habitat for shallow water areas and wetland wildlife based on a large depth to bedrock, medium wetness, slight surface stoniness, low slope, and high permeability (based on the fact that it does not support standing water).  The absence of standing water decreases the chances of the study area being used by different species of waterfowl. 

The Finchford series, moving up slope, has a very poor potential as habitat for wetland plants, shallow water areas, and wetland wildlife.  This is due to the increase of soil texture, depth to bedrock, surface stoniness, permeability, and the decrease of wetness.  Due to recent farming the vegetation was limited to the species fleabane in this particular area of our study site.

Examples of some potential waterfowl to use this study area include those mentioned below with a link to a picture of each:

It is possible to create or restore parts of this study site, including the Farrington and Hoopeston areas.  This can be done by digging up the areas with a backhoe, down to the water table.  After that, it could take anywhere from 5-10 years for hydrophytic plants to grow and attract waterfowl.  This could be an expensive process due to the amount of money that would be required for projects such as burning, digging, landscaping, and replanting of favorable vegetation.  Money for projects such as those mentioned above could be obtained through organizations such as the Nature Conservancy, USDA-NRCS, Ducks Unlimited, Pheasants Forever, etc.  If money is not available to conduct projects such as those mentioned above, it is recommended to leave this study area to return to its natural habitat, and during this course look for future funding through the organizations mentioned above.    

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Contributed by Group 1: Brian J. Brezinski, Carrie Morrel, Kristi Stubbe, Laurel Weinkauf

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Outdoor recreation

The Hubbard soil site was classified as having three distinct soil series.  The first soil series was the 501A Finchford Loamy Sand,  0 to 3 percent slopes.  Outdoor recreational activities are considered moderately favorable.  Therefore, this soil can be used for campsites, picnic areas, playgrounds, hiking trails.  However, people responsible of these areas will need to be able to deal with the sandy conditions and the problem of wind erosion.  This soil is not recommended for golf courses because it is too sandy and dry.

The second soil series located in the lower wetland area of the Hubbard site was classified as Hoopeston.  Outdoor recreations that were stated earlier are severely limited in this area.  Since, major soil reclamation plans would have to be applied that would be not only difficult but costly, it is strongly recommended against these kinds of recreational activities.

The third soil series also located in the lower wetland area of the Hubbard site was classified as Farrington.  Farrington gets the same recommendation for outdoor recreation as Hoopeston.

Fig. 1:

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Contributed by Group 9: Kyle Oberg, Brian Toivonen, Todd Whalen

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Agriculture

The agricultural recommendations of the Hubbard site are influenced by many factors.  Recommendations include its relative location to the Chippewa River, slope, available water retention capacity, depth of water table, and wind erosion.  This site makes up the southern bank of the Chippewa River and is in the floodplain for the Chippewa River.  The slopes of the site are less than 4 percent, which are susceptible to soil erosion.  It must also be noted that this site is made up of three different soil types.

The Finchford soil’s major erosional hazard is wind erosion in the fall and early spring.  Contour farming limits soil erosion caused by precipitation events along with the use of grassed waterways.  Irrigation is very important to this soil due to its sandiness, its limited available water capacity, and excessive permeability.

Hoopeston soils are most susceptible to erosion during the spring and fall while they are unvegetated.  The Hoopeston series excessive permeability is due to high sand content which makes irrigation very important during low precipitation periods. 

Farrington soils, like the other soils in this site, are influenced by excessive permeability, limited available water capacity, and the potential for ground water contamination.  The Farrington series is also influenced by it's shallow water table.  With a water table depth of 1 to 2.5 feet, spring planting may be delayed and crops are damaged during most years unless the proper drainage system is installed.

The Hubbard site as a whole is suitable as an agricultural resource with the appropriate management of its soils characteristics.  

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Contributed by Group 6: Sarah Buss, Travis Franz, Breck Johnson, Paul Kruschke

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The soils found at the Hubbard site consist of three soils series: the Farrington loamy sand, the Finchford loamy sand, and the Hoopeston sandy loam.  The soils of this property are sandy and are derived from glaciofluvial outwash.  The landscape of this site includes a gradual slope located on the Chippewa River floodplain.  For residential development on the Hubbard property, many factors have to be taken into consideration before any construction can occur.

The soils on the Hubbard site seem to be prone to wetness, which can greatly influence development on the property.  This may influence the type of houses that can be built on the property.  The Finchford series is rated slight for dwellings with and without basements, but the Hoopeston and Farrington soils are rated severe for this aspect.  Due to this limitation, foundations on certain areas of the Hubbard site may be prone to flooding and need excessive pumping. 

There is also a problem with septic tank filtering on the Hubbard site.  This factor will also be a major influence on residential development.  All this soils on this site rate as severe for septic tank absorption fields.  Hoopeston and Farrington soils have a problem with absorption fields due to wetness, and Finchford and Farrington soils are poor filters for septic tank absorption fields.  It is not recommended that septic tanks be used on this property due to the high water table found on the site as well as the hazard of contaminating groundwater.

We recommend that residential development on the Hubbard site be limited due the problems of wetness and a high water table on the property.  It may be possible for development to occur on the Hubbard property, but it is recommended to build on the Finchford soils.  Building on other soils around the site could lead to flooding and unstable foundations due to the wet conditions of the soil.  If septic systems were used on this site, they  would be high maintenance and cause multiple problems due to the high water table, however alternatives may be available.  Nevertheless, these alternatives may be costly and have increased maintenance.  Residential development is possible on the Hubbard site as long as these limitations are taken into consideration.

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Contributed by: Trina Nowak, webmaster

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Soils within the Hubbard study site are consistent with three major soil series: the Finchford series, the Farrington series, and the Hoopeston series.  The soils on this site have a sandy nature which is prone to erosion and range from somewhat poorly drained to excessively drained.  The Hubbard site is mostly undeveloped land and has been used for farming in the past.  If commercial and/or industrial development is considered for this site, many features of the soil must also be taken into account before changes in land use can take place. 

Due to the sandy nature of the soils of this site, it is not recommended that the Hubbard site be used as a place for a sanitary landfill, sewage lagoon, or any other sort of waste disposal site.  All of the soils in this site rate as severe for these uses because of wetness and a hazard of seepage. 

The soils of the Hubbard site also have limitations with the development of small commercial buildings.  All of the soils on the property have a moderate risk of corrosion for steel and concrete.  This feature has the potential to create problems with building foundations.  Along with corrosion risks, the Hoopeston and Farrington soils are rated as severe for development due to wetness.  This could cause flooding and foundation problems for buildings constructed on the site.  In contrast, the Finchford soil is only rated as slight for small commercial buildings, so development may be possible on this area of the site.  However, construction would be difficult on all areas of the site because of shallow bedrock.  The shallow bedrock may also cause difficulties with excavations for underground pipe, sewer, phone, and electrical lines.

We do not recommend the Hubbard site for commercial and industrial development.  The problems with a high water table, shallow bedrock, and the wetness of the soils would make the construction of buildings difficult and maintenance would be costly.  Although it is possible to build on the Finchford soil series, we do not recommend this since the area is rather secluded and surrounded almost exclusively by farmland.  It is not an area that could bring in large amounts of employees or customers, let alone carry heavy truck traffic.  We recommend that this site be used for more low-impact activities, such as recreational land use.

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Contributed by: Trina Nowak, webmaster

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The soils at the Hubbard site can be used for construction and fill as source of roadfill, sand, gravel, and topsoil.  Roadfill can be excavated at a site and then used in road embankments.  Sand and gravel have multiple commercial uses in construction, such as in making foundations.  Unlike the uses for roadfill, sand, and gravel, topsoil is mainly used to cover an area so that vegetation can be established and maintained.  At the Hubbard site, we encountered three soil series: Finchford, Farrington, and Hoopeston and acquired information from the Pepin County Soil Survey to describe their suitability for specific construction and fill purposes.

The Finchford series was found to be a good source for roadfill, a probable source for sand and gravel, and poor source for topsoil due to its sandy nature, the presence of small stones, and the potential for area reclaim.  The Farrington series was found to be a fair source for roadfill due to wetness, a probable source for sand, an improbable source for gravel since it is too sandy, and a poor source for topsoil due to being too sandy.  The Hoopeton series was found to be a fair source for roadfill due to wetness, a probable source for sand and gravel, and a poor source for topsoil due small stones and the potential for area reclaim.  All the soils found on the Hubbard site have a moderate risk of corrosion for steel and concrete, which should be taken into consideration if the materials from this site will be used in building foundations. 

There is a potential for the Hubbard site to be used for construction and fill as a source for roadfill as well as sand and gravel, although the ratings vary for each soil.  However, the soils of this site are prone to erosion as well as wetness due to a high water table.  The high water table may also make excavation difficult and cause problems with bringing in heavy machinery.  Due to the problems that may occur at this site, we recommend extractive land use at the Hubbard site be avoided.

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Contributed by: Trina Nowak, webmaster

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Contributed by Group 7: Dana Bickelhaupt, Jed Durni, Kim Hornbeck, Elizabeth Major

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