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Soil survey organizes the landscape into units with common soil properties, characteristics, and classification. Soil survey units can be used to predict soil behavior and thus are useful for making management decisions and evaluating soil change. Traditionally, in the USA, soil survey mapping concepts have been developed with the dominant use of the landscape in mind. Current enhancement of soil survey includes documenting dynamic soil properties and soil change due to ecosystem management. Ecological sites are a concept used to describe “kinds of land” that have common potential kinds and amounts of vegetation and characteristic response to disturbance. In intensively managed (agronomic) systems, inputs (e.g., energy, fertilizer, irrigation water) can confound and homogenize vegetation indicators. In these situations, ecological site concepts, as constructed through state and transition models, can be differentiated based upon levels of soil function (indicated by dynamic soil properties) that occur as a result of the management (disturbance). Groupings and interpreting soil properties using an ecological site framework can serve as a useful tool for soil resource management and assessment and bring whole ecosystem insight into management decisions. Such organizational frameworks should provide information about both reference conditions and alternative management systems of soil functions or dynamic soil properties within an ecological site. Reference conditions might reflect either native or naturalized vegetation or the highest possible function that an ecological site could support. A framework for assessing soil condition in two ecological sites/soil types is examined. The capacity of each ecological site is different as indicated by soil carbon content and aggregate stability. This information allows for documentation of soil change (from reference to alternative states or management systems); it could also be used as a reference for soil health assessments and could be used to enhance soil survey with land use and management-specific information.

Land Resource Regions (LRR) M and L occupy predominantly the northcentral part of USA with the exception of MLRA 101 (LRR L) located on the northeastern part bordering Lake Eire. Both regions have been influenced by several glaciations that occurred between 10,500 and 2,500,000 years ago. The geology is dominated by Devonian/Ordovician rocks, sedimentary and granitic, and to a lesser extent by Cambrian (9 %) and volcanic (8 %) rocks. Soils in the regions have developed mostly on loess, till, and outwash materials deposited after glacier melt. The predominant soils are Mollisols and Alfisols formed on loess followed by Spodosols, Entisols, and Inceptisols formed on outwash rmaterials on stream terraces and valleys. Histosols are limited in extend occurring throughout the region on localized depressions. The region that is also known as the “Bread Basket” of the USA is comprised of soils that are relatively young and among the most fertile in the world. The rolling hills, loess plains, and outwash valleys support a wide variety of crops. Soils are neutral to slightly alkaline for the most part and relatively high in organic matter due to favorite climate conditions and historical predominantly prairie vegetation. Intensive agricultural practices have caused extensive erosion and systematic depletions of fertility and organic matter and continue to remain major concerns for soil resource management and environment issues such as water quality.

Saturated hydraulic conductivity (K sat) is an important soil parameter that governs water movement through horizons, pedons, and soil landscapes. K sat is infamous for its spatial and temporal variability, which contributes to the difficulty and considerable expense in measuring or otherwise quantifying it. Consequently, predictive methods such as pedotransfer functions (PTFs) that use physical soil properties, such as texture and bulk density, have been developed to derive K sat values. Soil texture and structure are key factors influencing K sat because of their direct relationship to pore size distribution. Quantitatively defining the combined effects of texture and structure on pore size distribution in a PTF is a difficult task. The objectives of this research were to: (i) estimate K sat based on pore characteristics derived from soil thin sections via image analysis; and (ii) compare the resultant values with field-measured K sat and with K sat estimated by a PTF using soil texture and bulk density parameters. We digitally scanned 39 thin sections from 11 pedons of soils derived from loess over till and/or over weathered sandstone. Soil voids were classified based on their size and shape. K sat was measured in the field using a Compact Constant-head Permeameter (Amoozemeter) and estimated using a Rosetta PTF. Simple and multiple linear regression (MLR) analyses were used to relate pore indexes and soil physical properties with measured and estimated K sat. The mean measured K sat was 0.74 cm h−1, whereas the PTF-estimated K sat from Rosetta and MLR were 0.36 cm h−1 and 0.49 cm h−1, respectively. The addition of pore characteristics into the model improved K sat predictions compared to predictions using Rosetta alone. The estimated K sat based on the model with added pore characteristics was better correlated with field-measured K sat (r = 0.82) than that based on Rosetta (r = 0.62). The addition of pore characteristics can improve K sat predictions. However, thin section void analysis from additional parent materials is needed.

The concerns about climate change have increased interest in understanding differences in soil carbon pools and availability. The objective of this study was to assess total Soil Organic Carbon (SOC) and mineralizable SOC (Cmin) dynamics and spatial distribution as controlled by slope position, in glaciated northern Indiana. We collected 210 soil samples from the 0 to 25 cm surface layer along 10-point transects along a soil catena. Total SOC was determined by dry combustion and Cmin by incubation. The spatial distribution of total SOC followed patterns related to soil wetness. Overall, the depression areas stored between 50 and 141 Mg C ha−1 or between 50 and 68 % more total SOC when compared to the drier areas. After 28 days of incubation (Cmin), depressions released 1.2 Mg C ha−1, which was significantly more than the drier areas at 0.8 Mg ha−1. These differences indicate the potential of wetter areas, to store C if converted to C accruing management practices. The mean daily rate of C-CO2 evolved decreased exponentially during the first 28 days from 1.5 to 0.2 μg g−1 h−1. The management of these targeted areas can potentially increase soil C stock in arable lands and assist managers in developing systems that will sequester soil carbon.