Saturated Zones and Soil Morphology in a Mollisol Catena of Central Iowa

Abstract

The zone of saturation plays significant roles in decisions regarding soil classification systems and land use both present and potential. This study was conducted to determine the status of water tables, morphological features, and groundwater hydrology and to evaluate the zone of saturation on selected soils (Aquolls and Hapludolls) of a Mollisol catena. Water table depths and the amount of precipitation were measured for a 10‐year period on five soils formed in glacial till or till‐derived sediments in central Iowa. Results show that the depth of the water table, duration of saturation, morphological features, and recharge and discharge to groundwater varied with geomorphic position in the Mollisol catena. In general, soils on summit and shoulder positions (Hapludolls) are not saturated and have high chromas without redoximorphic features in the B horizon, have deeper water tables, and have maximum fluctuation of water table levels. The soils on toeslopes and depressions (Aquolls) have the shallowest water tables, have the longest time of saturation, and have B horizons with gray matrices, bright mottles, and Fe‐Mn concretions. Nicollet soils (fine‐loamy, mixed, mesic Aquic Hapludoll) on backslope positions have intermediate characteristics. Redoximorphic features present in these soils are correlated with the fluctuating depth of the present‐day water table. The extent of recharge and discharge and artificial the drainage are contributing factors to the water table level. Data for water table level and calcite/dolomite ratio indicate that ephemeral recharge and discharge of groundwater occur in the soils on lower landscape positions. Recharge is the dominant process in the soils of higher landscape. This study was designed to contribute to the understanding of drainage class‐water table‐morphological features of soils in this region. The apparent drainage conditions and the redoximorphic features contribute to the testing and clarification of soil classification and soil taxonomy.

Soil Water and Shallow Groundwater Relations in an Agricultural Hillslope

“…Th e diff erence in this study and previous studies is that evapotranspiration was separately measured in this study, but only indirectly calculated for previous studies (Loheide et al, 2005;Schilling and Kiniry, 2007). (Khan and Fenton, 1994;Logsdon et al, 1999). In the Des Moines lobe the tile drains are not uniform but are arranged to drain the closed depressions.…”

“…Th is interaction could be important for increased plant available water (Van Bavel et al, 1968;Allmaras et al, 1975;Van Bavel and Ahmed, 1976;Stuff and Dale, 1978), solute transport back into the root zone (Berkowitz et al, 2004;Logsdon, 2007;Abit et al, 2008), soil water variation at diff erent landscape positions (Logsdon et al, 1999), possible evapotranspiration variation at diff erent landscape positions (Chen and Hu, 2004), and surface and lateral redistribution of soil water and eff ect on tile drainage (James and Fenton, 1993;Khan and Fenton, 1994;Kohne and Gerke, 2005). Further study is needed to quantify these eff ects in agricultural landscapes.…”

“…Th e total water table-depth-range will be greater over the season in drier years for summit, shoulder, and backslope positions than for toeslope and depressional areas (Logsdon et al, 1999). Khan and Fenton (1994) observed 10-yr water table-depth-ranges from 1.0 to 3.2 m for well drained, 0.4 to 2.8 m for somewhat poorly drained, and 0.2 to 1.2 m for poorly and very poorly drained fi elds that were tile-drained.…”

The relationship between soil characteristics and vegetation as a function of landform position in an area of the Flooding Pampa [Argentina]

“…Khan and Fenton (1994), Genthner et al (1998) and He et al (2003) indicate that the redoxymorphic features of the soil are the most easily observable sign of the presence and fluctuation of the water table. However, additional criteria such as thickness, surface colour (Reuter and Bell, 2001) and clayey textures (Megonigal et al, 1993) should be used as supporting evidence in assigning land use.…”

“…Thompson et al (1998) illustrated the relationship between soil properties and landscape in hydric soils, Khan and Fenton (1994) studied the soil morphology and the saturated zones of a Mollisol catena, and Seelig and examined the processes of sodic soils in relation to landform position. The spatial patterns of soil features have also been determined in relation to the elevational gradient of a wetland area (Reese and Moorhead, 1996).…”