MLRA-92 CLAY TILL FIELD INVESTIGATIONS

MAY 22-23, 2002

By Joe Jahnke and Al Giencke

Soil Data Quality Specialists, Region 10, St. Paul, Minnesota

**Background**

Much of MLRA-92 is composed of soils that formed in fine and very fine
textured glacial till (source from locally reworked lacustrine
sediment). The series that have been proposed for the very fine till
regions are the Cuttre, Amnicon and Miskoaki series. The states of
Wisconsin, Minnesota and Michigan have been adding these units and data
mapunits to ID legends in several County subset soil surveys. However,
there has not been agreements as to the soil moisture status, drainage
class, taxonomic classification and interpretation of these units on the
landscape.

This two day field investigation had the purpose of comparing
landscapes, materials and series concepts across state lines and
different geomorphic regions in order to reach a uniform understanding
and correlation of these soils.

**Participants**

The following soil scientists participated in this investigation:

John Lucassen Marc Diers

Jesse Turk Peter Weikle

Terry Kroll Roger Risley

Dave Hvizdak (day one) Joe Jahnke

Scott Eversoll Al Giencke

**Technical Summary and Conclusions**

Numerous sites in Minnesota and Wisconsin were observed within areas of
very fine clay till. The proposed series called Cuttre, Amnicon and
Miskoaki were evaluated as to the soil moisture status by landscape
position as well as their drainage class and taxonomic class.

All on this investigation agreed that the red clay till soils do perch
water above the very fine argillic horizon, across much of the landscape
on all slope classes. The depth to saturation (either observed on site
and/or documented by ongoing piezometer studies, refer to Figure 2 at
the back of this report) was generally at or near the surface on slopes
of 3 percent or less and at a depth of .5 foot on slopes 3 to 25 percent
or more. The **duration** of saturation was the main issue of
uncertainty. The field data gathered to date suggests the duration
decreases as the slopes increase. Some sharply convex shoulder slopes,
without a \"watershed\" above the slope, may have duration less than
that. It should be noted however, that the piezometer data gathered to
date has not been of enough long term to be finitely conclusive. Current
sites will be continuously monitored. Additional sites should be
established in Wisconsin and Michigan to verify the soil moisture status
across a larger area of MLRA-92 as part of a long term study.

**The normal drainage class/landscape relationship and soil taxonomic
class does not work well in this material.** Because of the high clay
content and shallow depth to the argillic ( 8 to 12 inches) and the
relatively high bulk density (see pedon S64WI-031-003 from Douglas
County, Wisconsin), water perches on this very fine argillic during
periods of snow melt and high rainfall. This is most common in spring
prior to \"leaf on\" by the tree species when there is little
evapotransporation but may occur almost any time period for brief
periods of heavy rainfall. Refer to Figure 1 for a proposed matrix
showing saturation/duration by slope class.

Refer to the Figures and photos at the back of this report for
additional information.

**Correlation/Classification/Interpretations needing futher agreement
and implementation:**

(Recommendations are in italics from the Region 10 office)

-   Is there a soil between the Bergland and Cuttre series with a
    different moisture status?

*From the observations the group concluded there was a soil with a wet
moisture status at the surface in spring and fall but had very little
ponding. The moisture status of this soil would have a shorter duration
of wetness than Bergland and longer duration than Cuttre.*

-   Should Bergland be restricted to having a long ponding duration?

*Consider revising the concept of Bergland to be ponded for three months
or more each year.*

-   How do the Amnicon and Cuttre series differ based on the results of
    this field investigation?

*If these soils have perching in the glossic above the Bt, it means that
the perching typically occurs in the upper 1 foot of the soil. The depth
to saturation in the Amnicon OSD states \"have a perched seasonal high
water table at a depth of 1.0 to 2.5 feet\". This would appear to be too
deep based on data and field observations. The depth to saturation in
the Cuttre OSD states \"have a perched seasonal high water table of .5
to 2.0 feet\". It would be difficult to separate these two series solely
on depth to saturation. The main difference on these soils again is
**duration** of saturation due to position on the landscape (convex Vs
concave positions). Duration of saturation has typically not been used
as series criteria, mostly because it is not a readily observable soil
property plus long term piezometer data is not available. Unfortunately
soil morphology, as a proxy to saturation, does not show noticeable
differences between landscape positions, other than very poorly and
poorly drained soils which seem to have hue differences.*

-   Are there soils on steeper slopes that do not have a wet moisture
    status for 1 month or less that fit the Miskoaki series?

*Although there was a consensus that all landscape positions can perch
water, the duration may be less on the Miskoaki series. Correlate this
series as needed and documented within geomorphic areas within the MLRA.
Where Miskoaki was mapped on short C and D slopes in Wisconsin it was
thought that wet moisture status due to perching would be 30 days or
more.*

-   How do we populate NASIS for the soil moisture status?

*Populate the soil moisture status by month documented by piezometer
data and tacit knowledge.*

*The duration will be less as the slope increases. Would be best to
populate a duration of 1 month even if we feel it is 2 to 3 weeks during
a given month. Need to warn users that saturation can occur. See
proposed matrix at the end of this report.*

-   How do we justify the depth to saturation if we do not have long
    term piezometer data at this time?

*We have a very good start at gathering supporting piezometer data. We
also have the vegetative community telling us the soils are likely wet
for periods of time (Red Dogwood, Sedge species in cropped areas, and
Salix species on steeper than typical slopes). We have numerous failures
of septic tank filter fields in areas of urban development (IE around
the City of Duluth.)*

-   Is there deeper saturation in these soils in addition to the perched
    conditions in the glossic horizon?

*Some of the piezometers in Minnesota did show a deeper zone of
saturation that occurred as the water moved down the profile, likely
along macro pores such as pressure faces, fractures or slickens. The
extent of this remains to be documented over time.*

1\. Proposed Matrix (From Roger Risley based on piezometer data to date)

Slope Weeks Sat. Weeks Sat. Months Position Drainage

above Bt \< 6\" Class

(approx. 14 in.)

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

0-1 28-36? 28-30? Mar-Nov depressional VPD-ponded\*

at some time

0-2 12-28 12-20 A-July level PD-surface

> Oct-Nov slightly at some time
>
> concave

1-6 10-16 6-12 A-June linear SWP

Nov

6-15 6-10 1-3 A-May linear- MWD/SWP?\*\*

convex

15-35 4-8 1-3 A-Early linear- MWD/SWP?\*\*

June convex

35+ 2-4 1-3 April linear- WD

convex

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

\*This particular position was not monitored by the St. Louis crew so it
is a bit of a guess.

\*\* Note sure of the drainage class for these short duration zones of
saturation.

Figure 1. A generalized schema for possible relationships between slope,
depth to saturation, duration, drainage class

![](media/image1.jpeg){width="5.996527777777778in"
height="4.175694444444445in"}

Figure. 2. This is the graph for 2001 on one of the monitoring sites in
Minnesota. A second site in Minnesota on steeper slopes also show the
same pattern of perching in spring and periods of heavy rainfall.

![](media/image2.jpeg){width="6.0in" height="4.5in"}

Photo. 1 Note the saturated soil conditions that occurred at a depth of
8 inches on a B slope unit of Amnicon.

![](media/image3.jpeg){width="6.0in" height="4.5in"}

Photo 2. The presence of Red Dogwood on steeper slopes is indicative of
saturated condition near the surface. Red Dogwood was fairly common on
all slopes looked at in the field. This photo was from a

D slope map unit.

![](media/image4.jpeg){width="6.0in" height="4.5in"}

Photo 3. The results of piezometer readings were shown and discussed on
this tour. Perching was common from 4 to 10 inches in spring in 2001 and
2002 on most sites observed in Minnesota, MLRA-92.

![](media/image5.jpeg){width="6.0in" height="4.5in"}

Photo 4. The group observing and discussing one of the Minnesota
piezometer sites on the red clay soils.

The installation of the piezometers was critical to assure the results
were meaningful.

![](media/image6.jpeg){width="6.0in" height="4.5in"}

Photo 5. This site was best correlated to a poorly drained soil, wetter
than the Cuttre series but not as wet (ponded) as the Bergland series.
It may need to be proposed as a new series in the red clay catena of
soils.

![](media/image7.jpeg){width="6.0in" height="4.5in"}

Photo 6. Many of the pedons observed has similar morphology. There was a
thin A horizon over a glossic horizon (best seen when dry) with a clay
textured Bt horizon. Redox features where hard to see unless in the
poorly or very poorly drained soil. The structural classes were better
expressed in the somewhat poorly drained and better catena members.

![](media/image8.jpeg){width="6.0in" height="4.5in"}

Photo 7. Many of the pedons observed had free water along the structural
faces. This likely meant that the soils were recently saturated or at
the point of becoming saturated. The rock here shows a glistening
surface of free water.

![](media/image9.jpeg){width="6.0in" height="4.5in"}

Photo 8. Saturation occurred near the surface on the somewhat poorly
drained Cuttre soil.