Executive Summary

The Weber Farm Site is located in southern Dunn County, Wisconsin near the confluence of the Chippewa and Red Cedar rivers.  The purpose of this website is to present the results of research designed to:  determine the genesis of soils within the study area and to provide the landowner with recommendations for suitable land uses based on soil knowledge.  

The study site is located in a landscape position that includes a bedrock controlled upland, adjacent concave lowland reentrants to the north and south, and the intervening steep, bedrock-controlled escarpment.  The landscape position of the study site with respect to these landforms is widely observed in Dunn County.  Variability of soil characteristics and the processes and factors that produced these characteristics have received little scientific attention, according to NRCS personnel responsible for updating the Dunn County soils map, natural, and interpretive data.  

Eight soil pits were excavated within the study site in representative slope and slope aspect positions in an attempt to capture the variability inherent in the soil continua across this complex landscape position.  Soil profiles exposed in these pits were described, photographed and sampled using standard NRCS field methods.  Samples were analyzed in the laboratory for particle-size distribution and organic carbon content. 

Like much of rural Dunn County, the study area has been used for cultivated crop production more-or-less continuously since the late 1800s.  Soils in the study area have been forming since the end of the Ice Age (about 13,000 years ago) in loess-derived silty parent material (silty glacioeolian deposits) and sandy parent materials weathered from the underlying sandstone bedrock.  Other soil forming factors such as climate (humid, continental) and natural vegetation (a mixture of oak savanna and mixed deciduous and coniferous forests) and organisms are uniform across the study area.  The soil forming factor that varies most across the site is landscape position and slope.  In this regards, the study area is divisible into three roughly equivalent areas:  upland, steeply sloping, and lowland portions.   

Soils exhibit considerable variation across the study area.  This variability is a reflection of the complex topography.  Soils on the upland and steeply sloping portions of the study site, mapped as UeD2 (Urne-Norden Elkmound loam, 12-20% slopes, eroded and HfC2 (Hixton loam 6-12% slopes, eroded) exhibit: thin solums with weakly developed horizons and structure over sandstone bedrock, silty to sandy textures derived from loess (glacially derived eolian sediments of unknown, but presumably late Wisconsinan age) and the underlying weathered sandstone bedrock (Ironton Member, Wonowoc Formation, a late Cambrian sandstone).  Solum thinning and simplified horizonation is especially apparent on steep slope shoulder positions adjacent to the upland portion of the study site.  These soils are consistent with the Inceptisol order.  Some profiles in upland and slope shoulder positions include a remarkably well-developed but often broken Bt-horizon at depth (usually formed directly above and/or in weathered bedrock).  The degree of development in these horizons (e.g., clay skins, redder colors, and stronger structure) is inconsistent with the weakly expressed soil development in overlying horizons.  

Soils formed in the adjacent concave lowlands are typically thicker but otherwise exhibit weak horizonation and structural development similar to the soils on the upland portion of the study site.  Evidence of recent deposition in one profile excavated in this portion of the study area includes a buried A-horizon overlain by bedded very fine to fine sands (and charcoal).   These soils are also consistent with the Inceptisol order.

The most significant soil forming factor and consideration with regard to land use in the study area is slope.  The sandy and silty texture soils in the study area are extremely susceptible to wind and water erosion when the stabilizing protection of vegetation cover is removed.  This is especially true in steeply sloping portions of the study area.  Soils in these portions of the study area already exhibit characteristics that are the direct result of soil erosion.  They are thin and sandy (due to the incorporation of sandy material derived from sandstone bedrock below them).   Much of the rich, fertile loess-derived parent material has been removed from this portion of the study area.  Soils in lower positions in the study area are thickened suggesting material eroded off adjacent uplands is, at least in part, being stored lower on the landscape.  In at least one case, redeposition of silty and sandy material eroded from upslope was rapid enough to bury a preexisting soil.    

Several lines of evidence suggest the severe soil erosion characteristic of much of the study area occurred recently, perhaps since the introduction of Euro American agricultural practices.  The presence of strongly developed Bt-horizons at depth in some upland settings indicate a substantial period of landscape stability, and soil formation, occurred during post-glacial time.  The weakly expressed horizonation above these horizons, and across the entire study area for that matter, suggests this extended period of landscape stability and soil formation has only recently been interrupted.      

We recommend that future land use of the study area mitigate for soil erosion.  Soils in the study area, though already affected by soil erosion, remain moderately fertile and suitable for cultivation.  Soils are thin so there is little likelihood of developing the study area as a "borrow pit", although sandstone bedrock could be easily reached with heavy machinery, if quarry activity was deemed economically viable.  Though thin, they can support some construction and can be used for a variety of earthen fill.  However, great care during any land use activity that removes or inhibits the establishment of vegetation should be taken.   Soil erosion control practices such as zero-tillage and contour plowing should be implemented if cultivation is to continue (at least sustainably).  Silt fences and soil berms should be in place during any construction.  Room for vegetated buffer strips should be left if the study area is to be used as a building site.  Soils at the site are best suited to "low impact" activities such as pasture or recreation areas.  Even if used for these purposes, care must be taken to control foot, animal, and vehicle traffic, especially on the steeper portions of the study area.  Any such activity that removes stabilizing vegetation will result in soil erosion.  Both soil erosion by wind (blowing and deflation) and soil erosion by water (sheetwash and gullying) is to be expected if the protection of stabilizing vegetation is removed and these soils are exposed.     

 

Introduction

Research Question and Objectives

Location & Physical Setting

Soil Forming Factors

 

 

Table of Contents