K. McSweeney

Identification of the spatial distribution of soils using a process-based terrain characterization

Abstract A simple process-based terrain characterization model was developed to identify the occurrence of soils over a complex landscape. Its basic proposition is that soil distribution can be most efficiently identified by the separation of pedogeomorphological units where similar hydrological, geomorphological, and pedological processes occur. The proposed model is a three-dimensional extension of the nine-unit soil landscape model. The two-dimensional conceptual and qualitative model is reinterpreted in terms of continuity equations describing the distribution of soil materials over hillslopes, and is implemented in a geographical information system (GIS) through the analysis of a raster digital elevation model (DEM). The application of this model at the Empire Prairie in southern Wisconsin, USA, shows a good agreement with the results of a soil investigation. The difficulty in modeling the diverse geomorphological and pedological processes at low lying slope positions and the influence of relict pedological features on contemporary soil formation, however, remain unsolved. This model can consider the spatial variability of soils both at the continuous and discrete scales, and is easily transferable to other slopes in a predictive manner. It is further expected to provide a quantitative tool to characterize surface topography in terms of process identification and resource survey, and also a priori information for spatially distributed ecological and environmental models.

Paleosols spanning the Cretaceous-Paleogene transition, eastern Montana and western North Dakota

Paleosols occur in exposures of the latest Cretaceous Hell Creek and Paleocene Tullock (= Ludlow) Formations in Montana and western North Dakota. These units are composed mainly of interbedded siltstones and sandstones of meandering fluvial origin. The paleosols indicate that changes in ancient soil development occurred concomitantly with the better-known faunal transition. In order of decreasing abundance, silty soils, sandy soils, organic soils, and volcanic soils are preserved. Pedogenic features present in these soils include roots, microscopic segregations of amorphous material, birefringence fabric, and soil structures. The features suggest that throughout the Cretaceous-Paleogene transition pedogenic processes in the region produced immature profiles, an observation consistent with the unstable, fluvial setting in which the ancient soils formed. Gleization was a dominant process in this setting, and podzolization modified some sandy soils. The association of the features enables recognition of O, A/E, Btg, Bhs, Bg, BC, Cg, and C horizons. During middle Hell Creek time, soils formed in a poorly drained setting that was only stable enough to permit incipient pedogenesis. The bulk of the pedogenesis occurred in levee and flood-plain deposits; soils also occurred on point-bar and crevasse-splay deposits. In topographically depressed regions, organic accumulations formed with minimal soil development. Matted plant debris is the product of this environment. Gley features and segregations of iron oxides around voids suggest fluctuation of the water table. By latest Hell Creek time, the mean level of the water table rose, and in the lowest Tullock (Ludlow) exposures, extensive ponded deposits are preserved. Vegetation accumulated at a rate sufficient for coal formation. The amount of fluctuation apparently was reduced, and pedogenesis was further inhibited, as indicated by the virtual absence of illuviated clays in the sediments.

Nest structure of ant Lasius neoniger Emery and its implications to soil modification

Abstract The ant Lasius neoniger Emery is one of the most abundant ant species found in the temperate regions of North America and has been studied primarily from an entomological standpoint. This study was conducted to characterize its nest structure and implications to soil modification. To study the structure, development, and micromorphological characteristics of the ant nests, we constructed three-dimensional models of the nests from excavated nest castings made with dental gypsum and ant farms with Plexiglas, and made thin sections ( ≈30 μm thick) from undisturbed field soil samples that contained the nests. We assessed the effect of the ant on soil chemical properties by comparing the composition of ant crater rim and nest materials with that of associated bulk soil. The ant nests consisted of underground branched networks of galleries and chambers concentrated in the upper 0.3 m of the soil, with a few vertical galleries penetrating to about 0.7 m. The galleries tended to be circular tubes (channels) 1.5 to 5.0 mm in diameter, whereas the chambers, connected by the galleries, bulged to diameters of 10 to 20 mm and were 30 to 50 mm in length. The volume of the nests ranged from 20 to 250 cm 3 . Walls of the nests ( ≈1 μm thick) were more consolidated and contained larger amounts of fine sand, silt, and colloidal material than adjoining bulk soil. The primary effect of the ants was mixing of the upper 0.7 m of soil. Estimated soil turnover time ranges, for upper 0.3 m soil, from approximately 1000 years for the grass border areas of a corn field to 2800 years inside the field. For soils between 0.3 and 0.7 m depths, estimated soil turnover time ranges from approximately 9000 years for the grass border areas to 24,000 years inside the corn field. Selective mining by ants of fine-particles, which concentrate in the upper tier of the soil, may also counter balance processes such as clay translocation and nutrient leaching that tend to degrade physical and chemical attributes of sandy soil surfaces forming in humid environment.

Profile cone penetrometer data used to distinguish between soil materials

In young glaciated landscapes the variability of soil materials imparts a major control on crop growth and yield and environmental quality associated with production agriculture. Two common soil materials found on these glaciated landscapes are glacial till and reworked loess. Soil materials can be characterized by a combination of physical and morphological soil attributes. We hypothesized that penetration resistance is the response signal to a complex of multiple soil attributes and can be used as an integrating indicator to map soil materials. Our objective was to test the ability of a profile cone penetrometer to map soil materials at landscape-scale. The study site was located in southern Wisconsin, USA, on soils developed in reworked loess material overlying glacial till, which are classified as Typic or Mollic Hapludalfs and Typic Argiudolls. We collected a dense data set of cone index profiles from a 2.73 ha area on a 10 m grid up to depths of 1.3 m. Additionally, we collected soil cores randomly at 21 penetration locations and analyzed these by layer for texture, bulk density, and water content. We utilized point elevation data collected with a differential global positioning system to create a digital elevation model and derive slope and compound topographic index to subdivide the study area into landform element classes. We used expert knowledge to characterize soil materials and subsequently measured soil attributes to identify soil materials. A hierarchical cluster analysis was used to group cone index profiles. Combining the sparse soil material data with the dense cone index and landform element data resulted in soil material information covering the entire study area. The spatial distribution of soil materials was visualized using a three-dimensional soil layer model. The proposed method is associated with large uncertainties in some areas and can be recommended only for coarse mapping of contrasting soil materials such as glacial till and reworked loess at landscape-scale, when used in combination with landform element data.

Development of pedotransfer functions for a profile cone penetrometer

In this study, we illustrate how profile cone penetrometers PCP , can be used to measure . penetration resistance rapidly to define zones similar in cone index CI , which can be related to u , and ii to evaluate the sensitivity of parameters used in these functions. The data set represented soils formed in reworked silty loess overlying glacial till and ror lacustrine sediments. The global data set were grouped into subsets in terms of similar CIs. A horizontal hierarchical cluster analysis and a vertical point inflection method were used to derive cone index layer . profiles CILP1 to CILP5 . Variability of CI within CILPs was small and variability of CI among CILPs was large. Within each group, CI was regressed with soil physical properties to develop 2. pedopedotransfer functions. These were evaluated using the coefficient of determination R.A sensitivity analysis was executed to evaluate the relative importance of different parameters in the regression models. For the total data set, R 2 ranged from 0.35 to 0.48. Pedotransfer functions for the CILPs showed largest R 2 with 0.62 for CILP1, 0.76 for CILP2, 0.70 for CILP3, 0.63 for CILP4 and 0.98 for CILP5. Depth, r , clay content and u were variables with large predictive b power. Textural variables had strong predictive power in the top layers, CILP1 and CILP2. In CILP4, clay contents along with r and u were variables with large predictive power. In contrast, b the predictive power of r and u was strong in layers CILP3 and CILP5, whereas soil textural b

Soil landscape models at different scales portrayed in virtual reality modeling language.

Most state-of-the-art manipulations and visualizations of soil data use geographic information systems to portray soil landscapes in two dimensions (2-D). Nevertheless, soil attributes are distributed continuously in three dimensions (3-D) across landscapes. The objective of this study was to investigate the use of Virtual Reality Modeling Language (VRML), a 3-D graphics language suitable for stand-alone or browser-based interactive viewing, to create 3-D soil landscape models at different scales. Four different locations in southern Wisconsin were selected to represent pedon, catena, catchment, and soil region scales. Soil data, including texture, cone index, and depth of soil layers, were used in conjunction with topographic attributes to create 3-D soil landscape models. Spatial modeling techniques comprised 2-D and 3-D ordinary kriging. We used Environmental Visualization Software (EVS) to export the geometry of 3-D objects, which were enhanced to include: (i) viewpoints, (ii) Munsell colors, (iii) texture maps, (iv) 3-D cross-section animation, (v) animations such as zooming and rotation, and (vi) primitive shapes to highlight areas of interest. Virtual reality modeling language is capable of describing and visualizing extremely complex shapes, such as complex soil layers or terrain. Visualization of Munsell soil colors was difficult to implement because there is no hardware or software independent color-management system available in VRML. Animation techniques were valuable to high-light specific characteristics of each model. The accessibility of interactive VRML models via the World Wide Web and the portability of these models across platforms facilitate the entry of soil science into the virtual world of cyberspace.

Ant burrow effects on water flow and soil hydraulic properties of Sparta sand

Abstract Macropores generally have a significant influence on soil hydrologic processes. Ants create large burrows that may function as macropores, thus creating a potential for rapid movement of water and water-soluble chemicals in soil. This study was conducted to characterize the impact of ant burrows on hydraulic properties of a Sparta sand (uncoated, mesic Typic Quartzipsamments), and to determine the potential for preferential flow of water in these macropores. We measured steady-state water flux in areas with and without ant burrows, using a tension infiltrometer, in no-till (NT) and moldboard-plow (MP) maize ( Zea mays L.) plots. The results from these measurements were used to estimate hydraulic conductivity of saturated soil, K s , soil macroporosity, Φ m ( r ), and macroscopic mean pore radius, r c . Because, during a rain or irrigation event, only those ant burrows that open to the soil surface would contribute to water flow, we also monitored the impact of sprinkler irrigation on the number of burrow openings. Macropores created by ant burrowing activities did not contribute significantly to water flow in this sandy soil, and they had little effect on K s , Φ m ( r ), and r c in either NT or MP plots. One of the main reasons for the lack of burrow effect on water flow was that the burrow openings tended to close during an irrigation or rain event. We found that 80% of the total burrows in a given area closed after the application of 5 mm of irrigation; however, 80% of these were reopened within 2 h.

Geographic Information Systems in Agronomy

Publisher Summary This chapter is intended to provide an introduction to geographic information system (GIS) and associated landscape tools and to illustrate the ways in which they are being used in various aspects of agronomy. GIS technology is bringing about rapid changes in the way that agronomic analysis and management are being conducted. GIS coupled with remote sensing, Global Positioning System (GPS), electronic sensors, and computer technologies is providing new methods for data acquisition, storage, processing, analysis, and modeling. These new tools allow us to quantitatively describe landscapes and processes. The chapter discusses site-specific farming (SSF)—that is, farm management based upon variable soil and microclimate conditions that occur within most fields. SSF reduces waste, because fertilizer and herbicide—for example—are applied only where needed. New and/or improved models need to be developed to fully take advantage of the spatial nature of the data provided by these tools. The development of these models will rely on spatial statistical analysis techniques to quantify the accuracy of input parameters and model output. Many new tools are being used in this rapidly evolving field of GIS. Three-dimensional scene simulation, visualization, and animation linked with remote sensing and image processing technologies, and real time data collection will be needed in the study of agronomic systems. The development and use of three-dimensional GIS and spatiotemporal GIS will be an increasingly important area of research. The agronomic community—including farmers, land managers, fellow scientists, policymakers, and the general public should benefit from this evolving and expanding field.

Soil layer models created with profile cone penetrometer data

In creating soil layer models for our study site, we were challenged (i) to express vagueness of our soil data, while at the same time maintaining adherence to systematic classification principles, and (ii) to describe continuously the spatial distribution of soil materials and layers in three dimensions. We developed a method to create 3-dimensional (3-D) continuous soil layer models describing the distribution of soil materials, reworked loess vs. glacial till. Soil attribute data such as texture, bulk density and water content, in combination with penetration resistance obtained with a profile cone penetrometer on a 10-m grid, were used to describe soil materials and layers. We compared crisp hierarchical clustering with fuzzy k-mean classification in creating soil layer models for a 2.73-ha site in southern Wisconsin. The continuous 3-D soil layer models were developed using horizontal ordinary kriging and vertical linear interpolation. Validation proved that the crisp 3-D soil layer model predicted soil layers more accurately than the fuzzy 3-D soil layer model. We conclude that at the working scale, the crisp classification is superior to the fuzzy classification.

Micromorphological and SEM analysis of cretaceous-paleogene petrosols from Eastern Montana and western North Dakota

Abstract Microscopy is used to distinguish pedogenic features from those associated with primary sedimentary fabric and non-pedogenic diagenesis in a suite of 65 million year old sediments. Sand-to-clay-sized material was deposited in meandering river systems over a broad coastal alluvial plain, and pedogenesis occurred in all lithologies. A variety of petrosol (lithified soil) horizons which exhibit both syndepositional bedding and pedogenic and non-pedogenic diagenetic features remains today. Features attributable to the in-situ interaction between root and soil provide the most convincing evidence of pedogenesis. In addition, features such as illuvial clay and iron-oxide accumulations around voids, which are commonly but not exclusively associated with soil environments provide accessory evidence of pedogenesis. Stress-related void and ground-mass birefringence fabrics are evident in the petrosols and some purely sedimentary deposits, and thus cannot be used as diagnostic indicators of pedogenesis. In this fluvial setting, erosion and transport of soil material occurred, which is indicated by the presence of pedorelicts in petrosol horizons and purely sedimentary deposits. Detailed study both by petrographic and by scanning electron microscope elucidates pedogenic indicators not visible in hand samples. Such tools are useful in resolving ambiguities between pedogenesis and non-pedogenic diagenesis.