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Long-term Agro-ecosystem Research in the Central Mississippi River Basin, USA:
Introduction, Establishment, and Overview
E. John Sadler, Robert N. Lerch, Newell R.
Kitchen, Stephen H.
Anderson, Claire
Baffaut,
Kenneth A. Sudduth, Anthony A. Prato, Robert J.
Kremer, Earl D.
Vories, D. Brent Myers,
Robert Broz, Randall J. Miles, and Fred J. Young
The material below is supplemental to the main article section titled:
Geophysical Setting and Anthropogenic Changes
Contributing to this section were the following authors listed in the main paper:
D. Brent Myers, Newell R. Kitchen, Stephen H. Anderson, Randall, J. Miles, Fred J. Young
INTRODUCTION
This material is supplemental to the section of the same title in the Overview paper of
a series that documents data and research from the Goodwater Creek Experimental
Watershed (GCEW). The GCEW has been part of a larger USDA-Agricultural Research
Service (ARS) watershed network for more than 40 years and has a valuable store of long-
term watershed hydrological, meteorological, and water quality data. For the data and
research from the GCEW and the broader Salt River Basin (SRB) (6,417 km2 or 2478 mi
2),
selected as the Central Mississippi River Basin site in the ARS Long-Term Agro-Ecosystem
Research (LTAR) network, an understanding of the natural history and anthropogenic
influence is needed to provide a foundation for developing credible scientific interpretation.
The natural history, including genesis of the landscape and soil resource, is needed for a
complete understanding of current natural processes active and important in the region.
Anthropogenic activity within the region also needs documentation in order to comprehend
how man’s activities have impacted soil and water resources. While much of the information
found here exists in the literature, it has been widely scattered. Further, this summary and
synthesis allows for a more comprehensive understanding of the past and current interactions
between watershed resources and land management, and for development of future
comprehensive management strategies.
GEOPHYSICAL SETTING
Agroecosystem research must derive conclusions about best management practices
based on a clear picture of the soil and landscape properties, and processes at work. It is a
central goal of such research to manage systems in such a way to sustain productivity on
these irreplaceable resources. The Central Mississippi River Basin, the SRB, and the GCEW
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occur on a post-glacial landscape along the southernmost edge of the ancient Laurentide Ice
sheet. The features and properties of these landscapes have interacted with management
systems and land uses resulting in both productive agricultural output and key failures in
ecosystem function. These failures are documented for Northeast Missouri, the SRB, and the
GCEW in this paper series and include soil erosion, stream sedimentation, and
ground/surface water nutrient and agrochemical pollution. Specific soil-landscape properties
are critical drivers for these vulnerabilities including; fractured glacial till, gently sloping
incised and highly erodible topography, slowly permeable argillic horizons, an intermittent
perched water table (episaturation) causing subsurface lateral flow, and the spatial patterns of
these features in the landscape. In this section we describe these features and properties and
discuss the landscape processes that impact agroecosystem function.
Geographic and Hydrologic Context
The study region ranges from the field scale to large watersheds but are applicable to
much of Northern Missouri. The findings of these works are also potentially applicable to
parts of Southern Iowa, and Southern Illinois, because these regions have similar soil
landscapes and land uses. The Central Mississippi River Basin encompasses more area than
this, representing, in concept, landscapes of the southern corn belt where thin loess over till,
or thin loess over residuum occurs. These landscapes can be generally described as dissected
upland plains with alluvial benches, floodplains, and riparian corridors. The more specific
Northeastern Missouri context of this paper series occurs on the landscapes straddling the
Grand Divide of the Missouri and Mississippi rivers (Figure 1). The SRB is composed of 3
major basins, the North and South Forks of the Salt, and the Salt. Within the South Fork basin
is the Long Branch watershed which contains the GWCEW.
General Chronostratigraphy
The character and function of Northeast Missouri’s soil-landscapes arise from three
key materials beginning with the underlying sedimentary bedrock, formed during the
Carboniferous period (359 Ma to 299 Ma). These layers help define the general topography
and drainage network. Above that bedrock, multiple layers of moderately dissected
Pleistocene epoch (2.5 Ma to 11.7 ka) glacial tills define the visible landforms. Finally, soil
profiles with important hydrologic control are formed in till, and mid-late Pleistocene (126 ka
to 11.7 ka) pedisediments and loess. Pedisediments are comprised of a basal mix of glacial
till and loess after glacial retreat and during initial loess deposition. The loess is distributed in
a more or less continuous mantle of variable thickness except on areas of significant slope or
instability where the underlying pedisediment, till, and sometimes bedrock may outcrop. The
remaining key parent materials are alluvial deposits of eroded till and loess in valleys and
floodplains.
Bedrock Geology
The overall topographic trends and locations of the major divides and river systems in
Northern Missouri are a vestige of the pre-glacial landscape (circa 2.5 Ma). That landscape
has been buried, but was developed in residuum of the same sedimentary geology as the
current bedrock. This bedrock is the remains of the Cambrian Platform which formed from
materials deposited beneath shallow seas which fluctuated in extent across central portions of
North America. The Cambrian platform in northern Missouri includes carbonate, shale, and
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sandstone rock (Ruhe, 1969; Allaby and Allaby, 1999; Grimley, 2000) and significant coal
deposits, but is predominantly limestone. This bedrock outcrops on some of the steeper
landforms along the lower reaches of major drainages and provides some control on the
elevation of these channels. The Cambrian Platform in northern Missouri was truncated to the
Pennsylvanian or Mississippian layers by glacial activity. The hydrologic function of the
bedrock has very little impact on the glacial till aquifer but the bedrock topography guided
the route of glaciers, and their subsequent drainage networks. These drainage networks still
exist today.
Pleistocene Glacial Deposits
Just above the bedrock are thick deposits of glacial till and outwash sediments that
were laid down during the Pleistocene epoch. Glacial till accumulated in multiple layers up to
100 meters thick and averages about 40 meters thick across the GCEW (Sharp, 1984). Glacial
advances repeatedly terminated in Central Missouri, constrained by increasing elevation at
the margin of the Ozark dome. This limitation set the current course of the Missouri River.
The maximum advance of the pre-Illinoisan Laurentide ice sheet occurred about 2.4 Ma
(Rovey and Balco, 2010), but was reached multiple times during the Pleistocene, crossing the
study region with distinct layers of till deposits. Northern Missouri has been glacier free since
about 0.2 Ma ago.
The chronostratigraphic record of the Pleistocene contains several identified and dated
materials. Just above the bedrock, pre-Pleistocene residuum, fireclay deposits, a buried
gelisol (2.58 to 2.47 Ma) formed in a periglacial environment (Rovey and Balco, 2010), and
peat deposits (Blanchard and Donald, 2005) are all observed. The Atlanta till formation (2.47
Ma), represents the earliest evidence of glaciation, and is overlain by the Moberly (1.2 Ma),
and the McCredie formations (0.75 to 0.2 Ma). The Moberly formation is not currently
differentiated. Three till subunits are recognized within the McCredie formation, they are the
Fulton member (0.75 Ma) the Columbia member (0.4 to 0.2 Ma), and the Macon member
(0.2 Ma).
These periods of active glacial advances (stadia) were alternated with regressionary
interstadial periods. The most recognizable features of these warmer ice free periods are
paleosols. Paleosols are named and consistently present in the chronostratigraphic record
across the region, though their spatial coverage is intermittent and they are not well correlated
in the literature. Their preservation is dependent on the stability of the landform and the site-
specific erosion processes occurring before burial in the next glacial stage. The major
interstadials in which paleosols formed occurred between the Moberly and McCredie
deposits and on top of the McCredie formation. The most recent paleosol, the Yarmouth-
Sangamon is widely observed and represents soil formation during the middle and late
Plestocene (0.2 Ma to 12 ka). Northern Missouri remained glacier free during the Illinoisan
(0.3 to 0.12 Ma) and Wisconsinan (0.1 Ma to 25 ka) glacial stages. The current
geomorphology developed during this open period, a net erosive environment which led to
greater incision of the glacial till and caused the overprinting of the Sangamon paleosol onto
the Yarmouth.
Till composition across Northern Missouri is a mix of glacially abraded geologic
materials from local and northern latitudes. Composition of the till is vertically and spatially
heterogeneous, varying in part by the era of deposition. The older Atlanta and Moberly
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formations are more influenced by the mineralogy of local bedrock. Thus, the clast lithology
in these deeper layers is 70 to 100% sedimentary in origin (Rovey and Kean, 1996; Roy et al.,
2004). Upper till layers are influenced by mineral sources further north than central
Minnesota and contain 45 to 60% crystalline lithology. These glacial deposits were laid by a
combination of mechanical force and melt-water runoff which occurred in a complex
overlapping manner resulting in layers and pockets of material with spatially variable textures
and density. In general the till texture is loamy and structure ranges from strong, very coarse
prismatic to structureless massive. Sand lenses and fractures are sporadically present leading
to large variability in saturated hydraulic conductivity (Ksat) of the tills. Sharp (1984) reviews
the available Ksat data from studies in Northern Missouri. These studies demonstrated several
orders of magnitude range in Ksat for glacial till layers (1.2x10-9
to 2.0 x10-2
m s-1
); also
demonstrating that in-situ tests typically had larger Ksat than core samples. Blanchard and
Donald (1997) described the till in the GWCEW as ‘a fractured system with a low
permeability, high porosity matrix’. They further documented that paleosol argillic horizons
can have an impact on the hydrologic system finding that two paleosol features within the till
had relatively smaller Ksat than till layers, likely due to the larger concentrations of pedogenic
clay.
Pedisediment, Colluvium, and Alluvium
The cessation of glacial activity in Northern Missouri at around 0.2 Ma pre-dates
surface loess deposits and left a long time interval for soil formation and erosion. The result
of this is the commonly seen Sangamon paleosol at the till interface. Truncation of the till and
paleosols occurred in many places due to erosion and long exposure, leaving a pediment, or
erosion surface (Schaetzl and Anderson, 2005). Subsequent loess deposits occurred atop this
till derived material over a time frame long enough for bioturbation, soilfluction, frost action,
and other in-place processes to mix coarser materials up into the first increments of the loess
deposit. The result of this basal mixing process is a ubiquitous distribution of pedisediment at
the glacial till-loess contact. The pedisediment contains an increase of 3 to 5 percent fine sand
relative to the overlying loess material, but vanishes in a diminishing gradient upward into
the loess. Pedisediment is quite common in most upland soil profiles in the GCEW from
summits to footslope positions. Colluvium is frequently seen in concave footslope positions
in areas with steeper dissection. These areas are influenced by soilfluction and erosion
occurring upslope to the immediate area. Alluvium is common in the riparian corridors
between the upland landforms. The alluvial fill derives from three major timeframes and
processes, glacial recession, post-glacial pediment formation, and the Illinoisan and
Wisconsinan era influx of loess into the system. Terrace bench positions at valley margins are
derived consequence of the earlier processes while the current floodplains are narrower due
to less water influx in the post-glacial period, and reduced sediment delivery in the Holocene
era (Bettis et al., 2008). Alluvium in the GCEW area is silty to loamy in texture with little
sand content compared with larger river basins.
Late Pleistocene Loess
As noted above, glaciers covered much of the upper and central Midwest during the
Illinoisan and Wisconsinan glacial stages while Northern Missouri remained glacier-free.
Nevertheless, the deposits of these glaciers were eroded by the meltwater created in their
recession, making their way to Northern Missouri in the major river systems. This eroded,
silty material was moved during fluctuating melting conditions and, intermittently deposited
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on the Missouri River flood plains (Schultz and Frye, 1965; Ruhe, 1969; Follmer, 1983;
Guccione, 1983). The late Pleistocene and early Holocene periglacial environment was cold
and arid with a westerly to southwesterly paleowind (Muhs and Bettis, 2000). Exposed
fluvial sediments were transported by wind erosion and re-deposited on downwind landforms
and left as loess deposits. The chronostratigraphic result of the Wisconsin glacial regression
is the most recently deposited parent material, the Peoria loess. Many of the modern soils of
the Central Claypan Areas in both Missouri and Illinois, including the GCEW, are formed in
this layer that was deposited during the timeline of 25 to 7 ka. Smectites and mixed-layer
illite smectites are the primary clay-sized mineral component of the Peorian loess
(Nizeyimana and Olson, 1988; Burras et al., 1996; Young and Hammer, 2000).
Regionally, thickness of the silty loess veneer varies with distance from its source and
was distributed anisotropically according to prevailing paleowinds (Ruhe, 1969; Muhs and
Bettis, 2000). The study region is on the east-central side of Missouri with most of the state
separating it from the southerly course of the Missouri river on the western border of the state.
This portion of the river is perpendicular to the paleowind and loess thickness decreases from
as much as 30-meters in the deep loess hills adjacent to the Missouri and Mississippi rivers to
less than 2-meters on broad flat interfluves in the Missouri Central Claypan Region
(Guccione, 1983).
Soil-Landform Relationships
Parent materials and soil morphology in Northeast Missouri are strongly correlated to
landscape position and geomorphology (Figure 2). Key features with landscape dependence
are thickness of loess, and depth of and clay content in the argillic peak. Local landscape
processes have caused the loess cap to vary in thickness systematically with slope and
landform (Ruhe, 1969). Maximum accumulation of loess occurs at summits and on divides.
Because of the flat topography, runoff does not accelerate; thus the detachment and transport
of soil particles is minimal (Jamison et al., 1968). As slope increases from shoulder to
backslope, the surface is less stable. Gravity, soilfluction, and runoff cause slumping and
detachment, and loess thickness decreases. Loess may be eroded away entirely at some
steeper incised landforms, exposing pedisediment, or the surface of the glacial till. These
processes also caused the accumulation of colluvial hillslope sediments composed of the
eroded silt, pedisediment, and till in concave landscape positions (Young and Geller, 1995).
Clay content in these soil profiles has a peak-shaped continuous depth function
(Myers et al., 2011). The depth and amplitude of the profile peak clay content also varies
systematically in these landscapes. Summit positions exhibit the most, abrupt argillic
horizons having the greatest clay content and form entirely in loess. Down-slope positions
have a larger portion of silt and sand material arising from pedisediment and glacial till
within 1-m from the surface. The coarser pedisediment typically does not influence the
summit position until >1 m depth while the shoulder position can have pedisediment at about
75 cm. Depending on the history of erosion, the backslope position can have loess,
pedisediment, or glacial till at the surface, and frequently has all of these materials within the
top 1 m of the profile. The footslope position typically has loess-derived colluvial sediments
and pedisediments over a deeper argillic horizon.
Terrace, creek, and river bottom soils are a smaller portion of the landscape than
upland positions, but are some of the most productive soils in this region as the silts and
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loams dominate the soil profile. Terraces tend to have similar profiles to summit positions.
Though they are the result of glacial erosion and fluvial deposition, they existed as stable
landforms during the late Pleistocene (Bettis et al., 2008) and have a thick loess covering.
Below terrace positions, the current flood plains tend to have a very diverse range and
heterogeneous distribution of fluvial sediments with clayey to sandy texture.
Claypan Genesis
The claypan feature prominent in the study area is an extreme variant of the peak
shaped accumulation of clay content in argillic horizons commonly seen in many Alfisols.
This argillic peak is formed due to chemical and physical weathering processes. Subsequent
to deposition, weathering of these collected materials has occurred in the temperate,
subhumid environment of the Holocene epoch (Ruhe and Scholtes, 1956). Because of the thin
loess deposit (1 - 2 m), flat topography, finer particle size, and the Holocene climate, the soil
minerals have undergone intensive weathering (Bray, 1935; Jamison et al., 1968) relative to
thick loess deposits.
The claypan feature has both physical and chemical provenance. Chemical weathering
processes include chemical transformation of primary and secondary minerals, and neo-
formation in-situ from dissolved mineral components left behind as evapotranspiration
seasonally dessicated the profile (Bray, 1935; Nikiforoff and Drosdoff, 1943; Whiteside,
1944; Wambeke, 1976). Physical translocation and accumulation of clay sized particles also
occurs. A constructive interference develops in the argillic horizons, whereby illuviated clay
films plug successively larger and larger pores and gaps between structural peds (Thorp et al.,
1959; Yaalon, 1983).
The accumulation of clay in argillic horizons (450 to 650 g kg-1
) is complemented by
eluviation in the superior E or BE horizon (200 to 300 g kg-1
) (Bray, 1935; Jamison et al.,
1968). Seasonal impermeability of the argillic zone causes a perched water table to form
directly above it. Solvent action and a fluctuating redox state are dominant in this part of the
soil profile. The felsic and mafic primary minerals found in the loess parent material are rich
in base cations, but they are largely weathered away from this portion of the profile and
degradation components of secondary minerals are shifted towards acid cations (Bray, 1935;
Albrecht, 1967; Lindsay, 1979). The remaining material in the eluviated zone has a larger
proportion of silt-sized quartz and other stable aluminosilicates with small CEC. Due to the
production of acid cations in weathering the eluviated zone has a pH of about 4.5. Large iron-
manganese concretions form here due to seasonally alternating redox state concomitant with
saturation and dessication. The coarser texture of the E horizon and impermeability of the
underlying clay leads to subsurface lateral flow (episaturation) and seepage downslope. These
are key hydrologic features of this landscape that have important impacts on water quality
and crop productivity.
ANTHROPOGENIC CHANGES
Historical information relative to settlement and associated land management changes
is critical for an accurate understanding of how water and soil quality changes occur in
watersheds. This history represents the Central Mississippi River Basin but primarily draws
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upon historical records written for the SRB (6,417 km2 or 2478 mi
2), of which the GCEW is a
sub-basin. Further, this historical sketch is not intended to cover all human activities, but is a
description of those elements having the most significant impact on land use, watershed
hydrology, soil and water resource impairment, and response with conservation practices.
Human Activity During Prerecorded History
Prior to European settlement, Native American habitation of the SRB likely followed
the archeological-derived timeline found in much of the U.S. Midwest area: 1) Paleo –
Indian period (ca. 12,500-10,000 B.P.) characterized with nomadic bands of hunters of ice-
age mammals (early only), deer, elk, buffalo, and turkey, and later in this period gatherers of
berries and nuts; 2) Archaic Culture period (ca. 10,000-3,500 B.P.) with predominantly small
upland villages where hunting, fishing, and foraging were replaced by some agricultural food
production; and 3) Woodland Culture period (ca. 3,500-700 B.P.) characterized by increased
advancement and utilization of pottery, weaving of plant fibers, and agriculture cultivation
practices, leading to long-term settlement and inter-tribal trading (Chapman and Chapman,
1983). Artifacts of all three periods were documented prior to construction of the Clarence
Cannon Dam that created Mark Twain Lake within the SRB (Henning, 1975). Leading up to
and overlapping with the time when European fur trappers and settlers arrived in the SRB,
various tribal groups occupied the area, surviving mostly on hunting and gathering, and less
on agriculture. Of note were the Sauk and Fox tribes that had migrated to the basin from the
Great Lakes region in the mid-1600s (Chapman and Chapman, 1983). As a result of the 1803
Louisiana Purchase, these Indian tribes relinquished rights to the U.S. Government in an 1804
treaty a large area west of the Mississippi River that included the SRB. Significant tribal
factions ignored the treaty for several decades and therefore land ownership was reaffirmed
by a second treaty in 1824 with the State of Missouri.
Early 1800’s Anglo-European Settlement
When Anglo-European settlers first moved into the SRB area, it was a combination of
deciduous forests (oak-hickory) and prairie grasses. However, what attracted the first settlers
was the presence of salt springs (salt being a scarce commodity on the frontier), and from
such the river received its name (O’Brien, 1984). The small salt mining operations, however,
never provided lasting strongholds. These operations were frequently attacked by Indians and
later failed because of less-expensive salt imports. Compared to other parts of the region,
movement of settlers into the basin was inhibited because of poor transportation routes. For
many years un-mapped game and Indian trails were all that were available (Henning, 1975).
In the 1820’s these trails were gradually worn into wagon roads and sparse settlement became
widespread throughout the Basin. Land purchase and settlement expanded rapidly from 1827-
1836 (a period of national economic prosperity), with ~80% of the public land within the
Basin purchased during this decade (O’Brien, 1984). Additional sale of public lands to
settlers was completed by 1860.
Most settlements started as clusters of three-to-five, usually-related families. Two
natural resources guided these settlers for homestead site selection: year-round water and
abundant timber. Because of high-water flooding in the bottomlands adjacent to streams,
homesteads were usually upslope from waterways in or adjacent to timber (O’Brien, 1984).
Stream water was needed for human and livestock consumption, as well as used for washing
purposes. Fish also helped meet food needs. Hand-dug, rock-lined wells were often
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constructed near the homestead for a cleaner drinking water source than stream water.
Readily-available timber was essential since it was the principle resource used for home and
barn construction, tools, cooking, and heating. Early homesteading on the nearly-flat prairie
was mostly absent since these grasslands lacked critical water and wood resources.
Since transportation was restricted, commerce was also limited and settlers generally
lived a simple agrarian lifestyle growing corn (Zea mays), wheat (Triticum aestivum), rye
(Secale cereale), pumpkin and squash (Cucurbita spp.), and garden vegetables. Typically
each homestead also had a few livestock serving as work animals and helping meet food
needs. Because an ample timber source was a necessity for settlement through much of the
1800’s, cropping first occurred on land cleared of timber or on prairie adjacent to woodlands.
Much of this land was adjacent to riparian areas, had significant slope, and thus was highly
vulnerable to erosion after plowing (Bratton and Smith, 1928). The thick turf of the broad flat
prairies was viewed less valuable for many decades and was mainly used for free-roam
grazing of livestock. Only as transportation means and roadways improved and alternative
building materials for making homes became more available did settlers move away from the
timbered riparian corridors and onto the prairie grasslands (O’Brien, 1984).
Landscape Transformation during the Late 1800’s
For the beginning of the second half of the 1800’s, a simple agrarian lifestyle was still
predominant throughout the SRB. Settlements remained small. Most families survived on
land parcels 10 to 40 acres (4 to 16 ha) in size (Bratton and Smith, 1928), though a few
wealthy landowners had emerged. Much of each family’s food continued to be raised or
grown on their own farm or was obtained by barter with nearby neighbors. Along with grain
production, almost every farm also had a small orchard and garden plot. Close by timber
sources were still heavily relied on for heating and construction. However, during the mid- to
late 1800’s mechanization was quickly advancing and allowed for more aggressive land
clearing and larger farming operations. Primary grain crops grown were corn, oats (Avena
sativa), wheat, and sweet sorghum (Sorghum vulgare). This mechanization period also led to
an ability to develop roadways that stimulated commercialization and economic
diversification, including grist mills, lumber mills, brick yards, and cash crops such as
tobacco (Nicotiana spp.), hemp (Cannabis sativa), and cotton (Gossypium spp.) (O’Brien,
1984). Frame and brick houses began replacing log cabins. Small villages and towns emerged
throughout the region, with Paris, Missouri, becoming the main commercial center of the
SRB. Growth and commercialization was also stimulated starting in the late 1850s with the
completion of the Hannibal and St. Joseph Railroad line in northern Missouri. Even with
transportation developments, little evidence exists of grain being shipped outside of the basin
in the 1800’s. During this time, cattle were fattened with locally-grown grain and herded into
the St. Louis, Missouri area for market (O’Brien, 1984).
Up through the Civil War, the wealthiest landowners owned slaves and had the largest
livestock and grain operations. While slave ownership was less than in other parts of
Missouri, the slave population in 1860 for the SRB counties was between 15-25% of the total
population (Howard, 1980).
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1900’s to Modern Times
Land Use Intensification Promotes Erosion
Early in the 1900s, the face of the Midwest rural landscape, including the SRB, began
a major transformation. People began migrating to the larger metropolitan cities, seeking for
a higher standard of living than what rural life offered. This resulted in shrinking
communities and increased farm size (Bratton and Smith, 1928). Investment in rural
infrastructure slowed and some smaller communities turned into ghost towns. At the same
time, improvements in agricultural mechanization helped affluent farmers expand their
enterprises, becoming wealthier. Poorer, less-efficient farmers went out of business. The
larger farms integrated grain feed production and livestock (cattle, hogs, and sheep)
operations. Extensive flat grasslands were plowed and put into grain production for the first
time. During this period, corn, oats, wheat and a new crop, soybean (Glycine max) was
typically grown. During World War I, corn grain prices soared, and so did corn acreage.
These changes in the agricultural landscape resulted in major shifts in land use and
cultivation intensity for all of Northeast Missouri. Intensified grain crop agriculture had an
immediate and dramatic increase on soil erosion that impacted total runoff and water quality
into rivers and streams of the SRB. Prior to the Civil War, much of the Salt River was noted
to have clear, clean water during most of the year (Howard, 1980). Fish and mussels were
plentiful. By the 1930’s, the streams were sediment filled and fish life was disappearing. Not
by coincidence, the first soil erosion plot research in the U.S. was initiated in 1917 on similar
soils on the campus of University of Missouri in Columbia, Missouri (just 80 km, or 50 miles
SE of the SRB) (Troeh et al., 1980). Multiple and damaging rainfall events caused severe
flooding, soil erosion, and property damage between 1926 and 1936. The impact was
devastating for croplands. An erosion survey in 1934 disclosed that 25% of cropped acres in
this region had lost from 75% to all of its topsoil, exposing the subsoil claypan (Bennett,
1939). Grain crop yields for many fields actually declined by more than 50% below yields
obtained in the late 1800’s.
Channelization and Drainage
While sod busting on the broad upland prairies for expanding cropland undoubtedly
had a major role in increased runoff and accelerated erosion, it coincided with other
significant hydrology-altering human activity, namely timber clearing, drainage, and
channelization. Spring and early summer floods commonly vexed farmers and homesteaders
on the bottomlands of northeast Missouri rivers, including the Salt. Their natural courses
tended to be tortuous and the common resolve was to develop straight ditches or canals
centrally located in the valleys for enhanced drainage. These were primarily occurring in the
forested bottomlands of the Salt River and its tributaries. Drainage projects in Northeast
Missouri began sometime in the first decade of the 20th
century when drainage districts were
formed for the major Northeast Missouri Mississippi River tributaries such as the Fabius, and
Wyaconda (Ball, 1913) and the Chariton (available from the Missouri Department of
Conservation at http://mdc.mo.gov/landwater-care/stream-and-watershed-
management/missouri-watersheds/chariton-river). Drainage districts were empowered by
State law (Missouri, State of, 1909) to authorize drainage districts organized by landowners.
These districts organized the tasks of surveying, designing, and commissioning the work to
be done by private dredging companies (Mason, 1984). Drainage districts were formed prior
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to 1909 on the Chariton (White, 1910), in 1908 on the North Fabius (Roberts and Bumbarger,
1908), and around 1913 on the Wyaconda (Ball, 1913). These local drainage authorities
levied taxes on landholders in the drained areas for repayment of bonds sold to subsidize
these projects.
For the SRB, enhanced drainage through channelization was especially focused on the
North Fork, one of the largest of the Salt River tributaries. Major sections of the river were
bypassed by drainage canals through the bottomlands, straightening out the meandering
natural stream system. Dredging in the main Salt River channel also occurred around this
period (Schrader et. al., 1917) (See Figures 3 and 4). Dredging produced a corresponding
increase in flow gradient that accelerated stream scouring. Channelization continued beyond
1950 as additional stream sections were straightened in more difficult terrain using modern
construction equipment.
These artificial drainage canals, now considered the actual channel of the river, are
now much different than they would have been at the time of construction. Design
specifications for ditches dug on the Salt River tributaries were probably similar to those for
the Chariton (White, 1910) and North Fabius (Roberts and Bumbarger, 1911). These were
dug to a depth of 2.5 m with a 6 m bottom width and having sides sloping at a 1:1 pitch. Now,
because of bank erosion and scouring, these channels are typically 3 to 5 m deep and 30 to 80
m wide with nearly vertical banks. It was the intent of those involved in these projects that
the artificial channels would increase in dimension and flow capacity and they have
succeeded. In the case of the Chariton River, the base level of the canal was already below
that of the original riverbed in less than ten years (White, 1910).
Altogether, these alterations in the length and base level of the Salt River and its
tributaries created significant change in the hydrology and stability of the landscape. Though
the overall goal of allowing excessive runoff to quickly move into and through stream
systems seemed necessary as agriculture intensified, there have been many unintended
consequences to the Basin. The most obvious impact has been the promotion of erosion due
to accelerated runoff. Channelization for improved drainage, working in concert with deep-
tillage cultivation practices on cropped fields, promoted severe erosion in many areas of the
landscape. With enhanced water flow in streams and ditches, deep gouges in the topography
have been caused by headcutting (or sometimes called “nickpoints”) backwearing up into the
landforms. Some of these headcuts unchecked by modern era conservation measures have
migrated into the upper reaches of the landscape. The straightened channels and unnatural
curves continue to promote severe bank erosion (Willet, 2010).
The GCEW is one of the headwater tributaries of the Salt and did not receive
significant channelization. However, major channelization and dredging occurred
downstream, and in other nearby watersheds. The degree to which these impacts have
propagated into GCEW is not clear. Like similar river systems in the region such as the
Blackwater (Emerson, 1971) and the Chariton (available from the Missouri Department of
Conservation at http://mdc.mo.gov/landwater-care/stream-and-watershed-
management/missouri-watersheds/chariton-river), the Salt River has not stabilized from the
channelization and drainage work that was initiated about a century ago. These landscape
alterations will likely continue to cause sediment-related water quality problems into the
foreseeable future.
11
Early Conservation Initiated
Government-directed public works projects addressing national erosion issues
resulted in the creation of the Soil Erosion Service within the Department of Interior in 1933.
That program was made permanent and transferred in 1935 to the newly formed Soil
Conservation Service (SCS) within the Department of Agriculture (Troeh et al., 1980).
Because of the severe gully and sheet erosion that quickly stripped away the limited topsoil
of the SRB, H.H. Bennett declared the need for conservation practices on these soils as
“urgent” (Bennett, 1939). In the late 1930’s the “McCredie project” (near present day
Kingdom City, in Callaway County, MO) was initiated by the SCS on 25,000 acres (10,000
ha) to assess and then implement soil conservation practices on 100 different farms (Bennett,
1939). This project was adjacent to the southern edge of the SRB and undoubtedly helped
stimulate new conservation practices within the Basin. Practices employed were diverse and
targeted the most obvious problems. They included contour tillage, contour strip cropping,
buffer strips, terracing, contour furrowing within pastures, gully control, impoundment,
fencing, construction of vegetated channels for runoff mitigation, liming, manure applications,
cover crops, green manuring, and retiring of highly eroded lands to trees, grass, or native
plants (Bennett, 1939). Additionally, the SCS established in 1937 a soil conservation
experiment station called the Midwest Claypan Experimental Farm near McCredie, MO
(Jamison et al., 1968), that became a primary runoff and erosion research location for the
University of Missouri Experiment Station and the USDA Agricultural Research Service for
the next 60 years. A major contribution of this station was data used in implementing the
Universal Soil Loss Equation (USLE) and its derivatives (Wischmeier and Smith, 1960),
which continue to impact conservation in the SRB and elsewhere. Results from these
demonstrations and research projects were recognized by famers and business leaders within
the region (Bennett, 1939).
Modern Era Farming Practices and Specialization
The trend of fewer and larger farms continued through much of the 20th
century as
motorized equipment increased in size and efficiency. In 1950, agriculture employed 33% of
the labor force in the Salt River area (Clarence Cannon Dam and Reservoir: Environmental
Statement, 1975). Over the next two decades, the number of cropped acres increased almost
10% while the labor force employed by agriculture decreased to less than 15%. During the
1970’s and early 1980’s, many small to medium-sized farms abandoned animal operations
because of poor profitability and focused on grain production. For Missouri farmers, debt
nearly tripled during the 1970’s and 80’s, resulting in a nation-leading number of farm
bankruptcies in 1985 (Demissie, 1986). Also during this period, a much higher percentage of
farmland became leased instead of owner-farmed. Predominant crops grown during this time
were soybean, corn, sorghum, and wheat.
During the last four decades of the 20th
century, farming operations evolved in
response to newer cost- and time-efficient technologies, and better-engineered equipment.
Further, awareness grew for enhanced soil and water conservation (addressed in next section).
Important changes that had direct impact on the landscape included: 1) seed bed preparation
changed from plow/disk to mulch till or no-till; 2) crop selection changed from rotations that
included three or more crops that often used cover crops to two-crop rotations (often corn-
soybean, sorghum-soybean, or wheat-soybean); 3) weed control changed from mechanical
cultivation to herbicides, with plant-active herbicides replacing many soil active herbicides in
12
the later years; 4) farm tractors and combines changed from 4-6 row power capacity and size
to 12-24 row power capacity and size; 5) crop genetics changed to include cultivars and
varieties with higher yield performance, greater pest resistance, and genetically-engineered
protection from certain herbicides to allow for a broader spectrum of weed control; and 6)
more synthetic fertilizers and less manure nutrients, wide-spread use of soil and plant
diagnostic tools, and better application equipment with more accurate control of rates (See
Figure 5).
Modern Era Environmental Challenges Identified and Response
In the latter half of the 20th
century, understanding of environmental issues nationally
evolved to include many challenges other than just runoff and erosion. These new challenges
became apparent in part because of active public-funded support for research and monitoring
programs. This awareness was also made possible because of advancement in scientific
instrumentation that allowed for quantification of chemical contaminants at smaller and
smaller concentrations. Measurement of chemicals in air, soil, and water mediums went from
parts per thousand to parts per billion in just a few decades. Increased concern for
environmental issues led to the formation of the U.S. Environmental Protection Agency in
1970. In 1972 major enhancements were made to the federal Water Pollution Control Act,
later renamed the Clean Water Act. This legislation more clearly defined the federal
regulatory structure for defining water quality standards, developing control programs,
permitting of discharge, and planning that addressed point and nonpoint source problems of
pollutants within U.S. waters (available from U.S. EPA at
http://www.epa.gov/lawsregs/laws/cwahistory.html). Since then the Clean Water Act has
been amended on numerous occasions, and other legislation was signed into law, which
expanded legal authority for addressing these concerns. Initially legislation focused on human
health, but with time broadened to embrace numerous ecological balances disrupted by
anthropogenic activity.
Concurrent with regulatory steps taken during the latter half of the 20th
century, more
comprehensive education, extension, and farmer programs and services followed the
improved scientific understanding of human interactions with the environment. This was
evidenced by the renaming of the SCS in 1994 to the Natural Resource Conservation Service
(NRCS), to reflect a broadened scope of landscape and watershed concerns this agency now
addressed (available from the USDA NRCS at
http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/about/history). Earlier in the century,
the model of empowering local farmers and ranchers to develop and implement practical and
specific conservation practices was promoted through organizing conservation districts, an
idea conceived by H.H. Bennett when Chief of the SCS. His philosophy was land owners
have the experience and resolution to make necessary management changes to preserve their
lands, and given the technical help and engineering suggestions, they should be trusted to do
so (available from the Missouri Department of Conservation at
http://www.maswcd.net/historydoc.htm). Relative to many states in the Union, Missouri’s use
of conservation districts has been stellar. This has in large part been because of a one-tenth-
of-one-percent parks, soils, and water sales tax passed by Missouri voters in 1984, and
renewed three times since (available from the Missouri Department of Conservation at
http://www.dnr.mo.gov/env/swcp/history.htm). The majority of the soil and water portion of
this tax has been used to assist agricultural landowners through voluntary programs,
prioritized by the statewide Soil and Water Districts Commission, but administered through
13
the 114 county-level Soil and Water Conservation district boards. This tax along with other
state and federal soil conservation programs and education initiatives (e.g., conservation
tillage and NRCS’s Conservation Reserve Program), have been credited for helping Missouri
to have the greatest decline in soil erosion rates when compared to other states (i.e., 171
million tons in 1982 to 95 million tons in 1992) (http://www.maswcd.net/historydoc.htm).
Prior to 1982, Missouri had the second highest rate of erosion in the nation and now it ranks
seventh.
These modern-era descriptions of federal and state soil and water conservation
initiatives are applicable for what has taken place in the runoff-prone landscape of the SRB.
With current grain cropping on about ~45% of the Basin acres (Lerch et al., 2005), excessive
runoff and the associated environmental problems persist in this watershed. Notable issues
from these grain crop acres include sediment movement into waterways and the Mark Twain
Lake, nutrient loss off fields resulting in eutrophication of lakes and streams, decreased crop
productivity with lost topsoil, and pesticide movement from fields into water bodies.
Livestock grazing occurs on ~30% of acres, with associated environmental issues.
Unprotected streams within grazed lands result in damage to stream banks, loss of riparian
habitat, and bacterial and nutrient contamination of steam water. Concentrated animal feeding
operations (CAFOs) and their associated challenges have also increased since 1990, with
over 15 facilities rated at 3000+ animal unit equivalents in the SRB in 2010 (available from
the Missouri Department of Conservation at http://www.dnr.mo.gov/env/wpp/afo.htm).
CONCLUSION
Examination of the genesis of the soil landscapes and how human activity has greatly
altered landscape resources is valuable for interpreting watershed research as found in this
series of papers on GCEW and SRB. Attempting to understand current land use activities and
condition of natural resources and formulating future management plans without the
historical context is like beginning a novel by opening it at the middle. Here we have
described how key landscape-dependent soil features, including thickness of loess and depth
of and clay content in the argillic peak, are important hydrologic drivers for watershed
vulnerability. Soil loss from erosion has significantly altered many fields cultivated for grain
crop production. Soil resources lost cannot be restored to pre-European settlement conditions.
Greatest devastation to the landscape occurred during the first half of the 20th
century, when
intensive rainfall followed deep tillage and/or extended drought periods, and major changes
in stream channels destabilized the landscape. Research and demonstration projects have
been essential for understanding the relationships of soil landscapes, hydrology, weather, and
anthropogenic activity. Early conservation responses focused on poor practices and
determining land use alternatives to help prevent further landscape resource degradation
while later responses also included a goal of restoring lost ecosystem function into the
landscape. Soil and water conservation practices have undoubtedly improved watershed soil
and water quality, but signs of impairment persist.
14
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18
Figure 1.
Geographic and hydrologic context of long term agroecosytem research in the Goodwater
Creek Experimental Watershed and the Salt River Basin. (Columbia, Missouri, Lat. 38.95°,
Lon -92.33°; Hannibal, Missouri, Lat. 39.71°, Lon -91.35°).
19
Figure 1.
The three primary parent materials in the study region are loess, glacial till, and alluvium.
Thick deposits of glacial till up to 100 meters are overlain with windblown loess. Sediments
from these sources are found in alluvial fill in valleys and floodplains.
20
Figure 3.
An aerial image taken Oct 14, 1950 from a portion of the North Fork of the Salt River
northeast of Clarence, MO shows a continuous 5.4 km section of channel dug in the early
1900’s. The channel length was reduced to less than half of the original 13.6 km. Compared
to Photo 2, part of the river had not been channelized by this date.
21
Figure 4.
A 2010 aerial image of the same area as Photo 1 showing channelization of the North Fork of
the Salt River. A comparison of these two photos shows the extent of channelization after
1950. After 1950, an additional 5.2 km section of canal was dug, which straightened 12.7 km
of original stream channel. In all, more than 65 km of channel were dug on the North Fork
above Clarence Cannon Dam, reducing overall channel length by about twice that amount.
22
1939 1956 1968
1982 1990
1939 1956 1968
1982 1990
Figure 5.
A sequence of aerial photos obtained from the USDA Farm Service Agency archives
illustrate some of the important changes that occurred between 1930 and 1990 for a typical
quarter section field (~160 acres, 64 ha) in the Salt River Basin: 1) larger fields were created
by merging of smaller fields; 2) loss of farmsteads as farmers managed larger acreages; 3)
loss of integrated grain and animal production systems; and 4) return of indigenous trees
along waterways and field boundaries.
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