The current soil survey of Monona County has revealed many differences in the alluvial deposits occurring in the Missouri River bottomlands. As a consequence the soils developed from these different deposits show numerous dissimilarities. It is the purpose of this paper to describe and explain the causes of the differences encountered. The principal factors in soil formation are climate, organisms, topography, parent material and time. In the Missouri River bottomlands of Monona County it can be assumed that climate and organisms are not important causes of soil differences. In general, differences in topography are closely related to differences in parent material. Thus parent material or time of deposition or both, must be the principal cause or causes of soil differences. The soils found on the Missouri River bottomlands are, for the most part, formed from alluvial materials. Some coarser alluvium may have been resorted by wind action subsequent to deposition but areas showing evidence of wind action are not extensive. The principal source of alluvium is the Missouri River; next, the tributary rivers and streams; and, of least importance, the steep bluffs that form the sides of the valley

McClelland, J. E.

Riecken, F. F.

White, E. M.

English

University of Northern Iowa

Proceedings of the Iowa Academy of Science Volume 57 Annual Issue Article 29 1950 Causes of Differences in Soil Series of the Missouri River Bottomlands of Monona County J. E. McClelland Iowa Agricultural Experiment Station E. M. White Iowa Agricultural Experiment Station F. F. Riecken Iowa Agricultural Experiment Station Copyright ©1950 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation McClelland, J. E.; White, E. M.; and Riecken, F. F. (1950) "Causes of Differences in Soil Series of the Missouri River Bottomlands of Monona County," Proceedings of the Iowa Academy of Science, 57(1), 253-258. Available at: https://scholarworks.uni.edu/pias/vol57/iss1/29 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. Causes of Differences in Soil Series of the Missouri River Bottomlands of Monona County 1 By J.E. McCLELLAND, E. M. WHITE, and F. F. RJECKEN 2 The current soil survey of Monona County has revealed many differences in the alluvial deposits occurring in the Missouri River bottomlands. As a consequence the soils developed from these different deposits show numerous dissimilarities. It is the purpose of this paper to describe and explain the causes of the differences encountered. The principal factors in soil formation are climate, organisms, topography, parent material and time. In the Missouri River bottomlands of Monona County it can be assumed that climate and organisms are not important causes of soil differences. In general, differences in topography are closely related to differences in parent material. Thus parent material or time of deposition or both, must be the principal cause or causes of soil differences. The soils found on the Missouri River bottomlands are, for the most part, formed from alluvial materials. Some coarser alluvium may have been resorted by wind action subsequent to deposition but areas showing evidence of wind action are not extensive. The principal source of alluvium is the Missouri River; next, the tribu-tary rivers and streams; and, of least importance, the steep bluffs that form the sides of the valley. In figure 1 the principal soil series mapped on the Missouri River bottomlands have been grouped. These groups, while based on soil morphology, reflect the probable origin and relative age of the deposits. Some of the characteristics of each group of soils are shown in table 1. The Kennebec and Salix groups of soils have adequate surface drainage and desirable profile properties for the most part. They are predominantly silt loam to silty clay loam in texture. For these reasons they constitute much of the better agri-cultural land in the Missouri River valley. The Missouri River meanders through a flat valley in Monona County, the valley varying up to 17 miles in width. At the present 1 Contribution from Soils Subsection, Iowa Agr. Expt. Sta., Ames, Iowa and Division of Soil Survey, Bureau of Plant Industry, Soils, and Ag. Eng., USDA cooperating. Jour. Paper No. 1780, of the Iowa Agricultural Experiment Station, Ames, Iowa. Project No. 1152. 2 Research Assistant Professor of Agronomy, Research Associate and Research Pro· fessor, respectively. 253 1McClelland et al.: Causes of Differences in Soil Series of the Missouri River BottomPublished by UNI ScholarWorks, 1950254 row A ACADEMY OF SCIE~CE [Vol. 57 Table I Characteristics of the Soil Groups of the Missouri River Bottom-lands of Monona County Textural Surface Source of Depth to Soil Group Range Color Alluvium Carbonates undiffer- sand to light olive Missouri calcareous entiated silty clay brown River throughout Al baton loamy fine dark greyish Missouri at or near sand to clay brown River surface Luton- mainly silty very dark Missouri in sub-Al baton clay to clay brown with River surface only transition olive cast Salix silt loam to very dark Missouri absent silty clay brown River Luton silty clay very dark Missouri usually to clay grey to River absent black to 30 inches Kennebec silt loam to very dark tributary absent silty clay brown rivers and streams and bluffs time the river is somewhat stabilized in its course by human agen-cies, but in places it is still actively cutting its banks. The soils of the area that is most frequently flooded in Monona County are shown in figure 1 as the undifferentiated group of soils. During periods of high water the banks along the firs·t bottom are not high enough to contain the river at many points. Consequently the second and higher level bottoms of the undifferentiated group are subject to frequent flooding unless adequate dykes are constructed. The Missouri River, especially when it rises to the flood stage, carries a heavy load. ·when the river overflows its banks the cur-rent of the overflow is reduced principally due to the frictional drag caused by vegetation. The reduction in the velocity of the current causes much of the load of the overflow to be deposited in the un-differentiated soil group area. The type of deposit apparently is determined by the current of the water at the point of deposition. In sheltered places where the current is markedly reduced accumula-tions of over four inches of silty clay deposits have been observed to occur in one year. Where the current of the overflow is swift such as at a break in a dyke or where vegetation is sparse, quite extensive areas have been covered with several feet of medium to fine sand. The coarse deposits are subject to some wind erosion 2Proceedings of the Iowa Academy of Science, Vol. 57 [1950], No. 1, Art. 29https://scholarworks.uni.edu/pias/vol57/iss1/291950] MISSOURI RIVER BOTT01ILANDS R41W LEGEND WOODBURY R46W OF SOIL GFWUP5 UPLAND KENNEBEC LUTON v SALIX >< x LUTON-ALBATON TRANSITION UND1Ff£'RENTIAT£'0 HARRISON COUNTY FIGURE I 501LGROUPS OF THE MISSOURI RIVER BOTTOMLANDS OF MONONA COONTY 255 ; CID .... :c: ; QI "' z until vegetation stabilizes them. It is not unusual to find numerous layers of sediments of different textures covering any area in the undifferentiated group of soils. Most of the soils with sandy layers at or near the surface are found close to the river or adjacent to an old oxbow. It seems probable that when the river becomes high enough to flood onto the higher level bottoms most of the sand is deposited before the point of overflow is reached. The soils found in the Albaton and Luton-Albaton transition groups of soils are less frequently flooded. These soils are only flooded during periods of extremely high water. Natural levees occur frequently in these areas. A diagram of a section of a natural levee is presented in figure 2 showing changes in the composition 3McClelland et al.: Causes of Differences in Soil Series of the Missouri River BottomPublished by UNI ScholarWorks, 1950256 IOWA ACADEMY OF SCIENCE llq• ot' HeTni• Serl•• ••tural ', ---~ Le••• ', Al baton Ser lea', ' ' ' ' ' ' ' lleout '-, J'lll ' ' ' ' ' ' ' ' 014•r Burle4 Soll ' ' Yertloal So•le: 1 lnell repreaenta 10 teec Horiaontel So•l•: l 1noh repreaenta 500 te•t PIXRIRll I [Vol. 57 A 81CTIOH 01 A Hl.'l'IDUI. LKYD '11 'l'llB lmlSOlllI RIYD SllOWIMa CHA!GIS IN lllCHAHICAL COMPOS ITIOK of the sediments comprising the levee with increasing distance from the source of the overflow. It has been observed that the sediments become finer textured and shallower in depth as the distance from the point of apparent overflow increases. Likely the Missouri River has coursed over most, or all of the valley floor at some time in the past but it has gradually tended to move towards the western edge of the valley in more recent times. Remnants of old natural levees have been encountered in most parts of the bottomlands. The Salix group of soils are formed from materials which seem to be old natural levees. The soils of the Salix group are dark and vary in texture from silt loam to silty clay loam. They are usually naturally well drained and fertile. They do not appear to have been flooded by the Missouri River in very recent times. The Luton group of soils occupies a very shallow trough between the Salix and Kennebec groups. The Luton group is, for the most part, composed of dark, poorly drained, clay soils. They appear to be of the same age as the Salix group of soils. Presumably in the past the Missouri River was stabilized just west of the Salix group of soils and the Luton soils represent the finer textured alluvium that was deposited during floods. As the Kennebec and Salix soils occur at slightly higher elevations than the Luton soils natural drainage is to the south. The slope gradient is only about one foot per mile to the south and many depressional areas occur. The in-adequate surface drainage together with the clayey nature of the deposits forming the Luton soils result in very restricted drainage. The tributary rivers entering the Missouri River valley in Monona County are the Little Sioux and Maple Rivers. Both of these rivers, before entering the Misouri River bottomlands, have 4Proceedings of the Iowa Academy of Science, Vol. 57 [1950], No. 1, Art. 29https://scholarworks.uni.edu/pias/vol57/iss1/291950] 1HSSOURI RIVER BOTTOMLANDS 2Si quite wide valleys. They meander along the eastern edge of the bottomlands before they enter the Missouri River. Both the Little Sioux and Maple Rivers have rather shallow banks and undoubtedly frequently overflowed in the past as they would do at the present time if they were not controlled. The soils along their bottoms before they enter the Missouri River valley are mainly silt loams in texture but some small areas of silty clay loam and silty clay soils do occur. As they approach the Missouri River valley the soils in their valleys become finer textured. Whether this finer material came from their watersheds or from the Missouri River of both is not apparent. Along most of their courses in the bottomlands they have built up narrow natural levees. The rather inextensive nature of these levees appears to indicate that these rivers have not been major factors in the deposition of alluvium on the Missouri River bottomlands. The steep bluffs along the edges of the Missouri River Bottom-lands have been the source of a narrow band of alluvial soils parallel to the faces of the bluffs. Where short drainage channels enter the valley small alluvial fans protrude onto the valley floor. Where the bluffs directly overlook the bottomlands the bluffs in-variably haYe a narrow band of mixed colluvium and alluvium near their bases. This alluvial-colluvial deposit flattens out into an alluvial, silt loam soil which seldom exceeds two hundred yards in width before the level valley floor is reached. As the texture of the surface soils on the bluffs and the alluvial and colluvial soils are about the same, it seems unlikely that the bluffs could have been an important source of alluvium for the finer textured bottomland soils. In figure 3 the nitrogen of profiles of several bottomland soil series* is shown graphically. These profiles were selected as being representative of the different groups of soils of the bottomlands of Monona County. Most of the nitrogen in the two profiles repre-senting the Albaton group of soils (Albaton silty clay, P-142 and Haynie silt loam, P-148) is in the top eight inches. In the Haynie *P-148 Haynie silt loam -41' W of SE corner of SW! of NE! of NW± of Sec. 34. T 85N, R 46W, Monona County. P-142 Albaton silty clay- 400' N and 35' E of SW corner of Sec. 3, T 83N, R 46W, Monona County. P-153 Salix silt loam -150' S of NE corner of SE:i of Sec. 24, T 85N, R 45W, Monona County. P-141 Luton clay- 100' S of NE corner of NW;J; of sec. 12, T 83N, R 45W, Monona County. P-150 Kennebec silt loam - 200 yards E of Maple River on road W of Castana. near top of S! Sec. 24, T 84N, R 44W, Monona County. 5McClelland et al.: Causes of Differences in Soil Series of the Missouri River BottomPublished by UNI ScholarWorks, 1950258 l 2 .. ... .r: u c:: -c: -IOWA ACADEMY OF SCIENCE [Vol.57 J ,,I ---, __ _ ,,,.. ---- --7' ( / I / I / I ,' I :' I : I I I I I \ ' -.... Group Al baton Salfic Lutoa Kennebec ..... ' .10 .15 Percent Nitroa•n Figure 3 Texture .silt loam - - __ silty cla1--------.silt }0811 -· - ·-cl•Y--«-t-1-1-6Ut loam----.zo .25 THE NITROGEN CONTENT OF FIVE PROFILES SELECTED AS BEING REPRESENTATIVE OF THE BOTTOMLAND SOILS OF MONONA COUNTY silt loam profile (P-148) a buried profile occurs below forty inches. The profiles representing the Salix, Luton and Kennebec groups of soils (Salix silt loam, P-153, Luton clay, P-141, and Kennebec silt loam, P-1 SO, respectively) have thicker accumulations of nitrogen. The greater accumulation of nitrogen in these three profiles to-gether with the absence of carbonates in their solums indicates that soil formation has been progressing for a considerable period of time without significant deposition of new materials. The Albaton soils, by the same reasoning, must have developed on alluvium that was deposited relatively recently. It is known that parts of the area occupied by the Albaton group of soils have been recently flooded. It seems apparent that differences between soils in the Missouri River bottomlands can be attributed to geological processes related to stream action. The soil textures are related to the depositional patterns of the river flood waters that spread out over the valley floor. The length of time that the soils do not receive new deposi-tions is dependent upon the ability of the river to build natural levees or cut deeper channels so that flood waters are retained with-in an area close to the river. 6Proceedings of the Iowa Academy of Science, Vol. 57 [1950], No. 1, Art. 29https://scholarworks.uni.edu/pias/vol57/iss1/29

Causes of Differences in Soil Series of the Missouri River Bottomlands of Monona County

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Causes of Differences in Soil Series of the Missouri River Bottomlands of Monona County

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