The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Craig J. Hickey - One of the best experts on this subject based on the ideXlab platform.
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imaging a soil Fragipan using a high frequency masw method
2014Co-Authors: Zhiqu Lu, G V Wilson, Craig J. HickeyAbstract:The objective of this study is to noninvasively image a Fragipan layer, a naturally occurring dense soil layer, using a high-frequency (HF) multi-channel analysis of surface wave (MASW) method. The HF-MASW is developed to measure a soil profile in terms of shear (S-wave) wave velocity at depths up to a few meters. While conventional MASWs use geophones as surface vibration sensors, the present MASW uses an accelerometer as a sensor to detect Rayleigh wave propagation generated by an electromechanical shaker operating in a chirp mode to achieve high frequency and high spatial resolution. With the method, the subsurface soil properties at a test site were measured, visualized, and evaluated. A 2-dimensional S-wave velocity image was obtained and from the contrast of the image, the presence, depth, and extent of a Fragipan were identified. The HF-MASW result was compared with those of site characterization made by invasive methods and a 2-dimensional image obtained by a penetration test. The results from the HF-MASW and soil characterization were in good agreement. The study demonstrates the capability of the HF-MASW technique for detection and imaging subsurface layers such as a Fragipan.
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Investigation of the near subsurface using acoustic to seismic coupling
Ecohydrology, 2009Co-Authors: Wheeler B. Howard, Craig J. HickeyAbstract:Agricultural, hydrological and civil engineering applications have realized a need for information of the near subsurface over large areas. In order to obtain this spatially distributed data over such scales, the measurement technique must be highly mobile with a short acquisition time. Therefore, some type of remote sensing or geophysical technique must be utilized. Geophysical measurements are sensitive to the distribution of physical properties, such as the electrical conductivity, dielectric constant, mass density, mechanical properties, etc., of the ground. In most instances, the geophysical properties must be reconciled with physical properties used by the soil scientist. This paper presents a preliminary investigation of the use of acoustic to seismic (A/S) coupling measurements for measuring the depth to the top of the Fragipan horizon. Fragipans influence the hydrology and ecohydrology of the soil on a field scale. A suite of traditional geophysical measurements was taken to characterize the soils at two sites with different depths to the Fragipan horizon. Data at these two field sites indicate that this A/S technique is sensitive to the spatial variability of the depth to the Fragipan horizon. At present, inversion of the A/S data for the Fragipan depth requires use of data from a separate geophysical measurement or soil cores to provide a field calibration.
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Investigation of the near subsurface using acoustic to seismic coupling
Ecohydrology, 2009Co-Authors: Wheeler Howard, Craig J. HickeyAbstract:Agricultural, hydrological and civil engineering applications have realized a need for information of the near subsurface over large areas. In order to obtain this spatially distributed data over such scales, the measurement technique must be highly mobile with a short acquisition time. Therefore, some type of remote sensing or geophysical technique must be utilized. Geophysical measurements are sensitive to the distribution of physical properties, such as the electrical conductivity, dielectric constant, mass density, mechanical properties, etc., of the ground. In most instances, the geophysical properties must be reconciled with physical properties used by the soil scientist. This paper presents a preliminary investigation of the use of acoustic to seismic (A/S) coupling measurements for measuring the depth to the top of the Fragipan horizon. Fragipans influence the hydrology and ecohydrology of the soil on a field scale. A suite of traditional geophysical measurements was taken to characterize the soils at two sites with different depths to the Fragipan horizon. Data at these two field sites indicate that this A/S technique is sensitive to the spatial variability of the depth to the Fragipan horizon. At present, inversion of the A/S data for the Fragipan depth requires use of data from a separate geophysical measurement or soil cores to provide a field calibration. Copyright © 2009 John Wiley & Sons, Ltd.
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in situ measurements of the Fragipan acoustic to seismic coupling signature
Journal of the Acoustical Society of America, 2002Co-Authors: Wheeler Howard, Craig J. HickeyAbstract:The phenomena of acoustic to seismic (A/S) coupling, observed and studied since the 1950s, has most recently been used to detect shallow buried objects [Sabatier and Xiang, J. Acoust. Soc. Am. 105, 1383 (1999); 106, 2143 (1999)] and monitor detonation of nuclear weapons [Orcutt, J. Acoust. Soc. Am. 105, 1038 (1999)]. At an air–surface interface airborne acoustic energy is coupled into the ground as seismic energy. The ratio of the seismic and airborne waves constitutes the A/S coupling signature, which is distinctive to the underlying structure. Seismic energy received by a geophone at the interface contains information, via reflected waves, about the underlying subsurface layer, media, and boundaries. Of particular interest in the Mississippi River Valley is the Fragipan layer. The Fragipan is the layer that directly affects the growth of crops, rate of soil erosion, and rate of water absorption in underlying layers. In this presentation, the A/S coupling signature data taken at an agricultural field sta...
Wheeler Howard - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the near subsurface using acoustic to seismic coupling
Ecohydrology, 2009Co-Authors: Wheeler Howard, Craig J. HickeyAbstract:Agricultural, hydrological and civil engineering applications have realized a need for information of the near subsurface over large areas. In order to obtain this spatially distributed data over such scales, the measurement technique must be highly mobile with a short acquisition time. Therefore, some type of remote sensing or geophysical technique must be utilized. Geophysical measurements are sensitive to the distribution of physical properties, such as the electrical conductivity, dielectric constant, mass density, mechanical properties, etc., of the ground. In most instances, the geophysical properties must be reconciled with physical properties used by the soil scientist. This paper presents a preliminary investigation of the use of acoustic to seismic (A/S) coupling measurements for measuring the depth to the top of the Fragipan horizon. Fragipans influence the hydrology and ecohydrology of the soil on a field scale. A suite of traditional geophysical measurements was taken to characterize the soils at two sites with different depths to the Fragipan horizon. Data at these two field sites indicate that this A/S technique is sensitive to the spatial variability of the depth to the Fragipan horizon. At present, inversion of the A/S data for the Fragipan depth requires use of data from a separate geophysical measurement or soil cores to provide a field calibration. Copyright © 2009 John Wiley & Sons, Ltd.
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in situ measurements of the Fragipan acoustic to seismic coupling signature
Journal of the Acoustical Society of America, 2002Co-Authors: Wheeler Howard, Craig J. HickeyAbstract:The phenomena of acoustic to seismic (A/S) coupling, observed and studied since the 1950s, has most recently been used to detect shallow buried objects [Sabatier and Xiang, J. Acoust. Soc. Am. 105, 1383 (1999); 106, 2143 (1999)] and monitor detonation of nuclear weapons [Orcutt, J. Acoust. Soc. Am. 105, 1038 (1999)]. At an air–surface interface airborne acoustic energy is coupled into the ground as seismic energy. The ratio of the seismic and airborne waves constitutes the A/S coupling signature, which is distinctive to the underlying structure. Seismic energy received by a geophone at the interface contains information, via reflected waves, about the underlying subsurface layer, media, and boundaries. Of particular interest in the Mississippi River Valley is the Fragipan layer. The Fragipan is the layer that directly affects the growth of crops, rate of soil erosion, and rate of water absorption in underlying layers. In this presentation, the A/S coupling signature data taken at an agricultural field sta...
M S Srinivasan - One of the best experts on this subject based on the ideXlab platform.
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Factors influencing surface runoff generation from two agricultural hillslopes in central Pennsylvania
Hydrological Processes, 2009Co-Authors: Anthony R. Buda, M S Srinivasan, Peter J. A. Kleinman, Ray B. Bryant, Gary W. FeyereisenAbstract:The variable source area (VSA) concept provides the underlying paradigm for managing phosphorus losses in runoff in the north-eastern USA. This study sought to elucidate factors controlling runoff along two hillslopes with contrasting soils, including characterizing runoff generation mechanisms and hydrological connectivity. Runoff monitoring plots (2 m x 1 m) were established in various landscape positions. Footslope positions were characterized by the presence of a Fragipan that contributed to seasonally perched water tables. In upslope positions without a Fragipan, runoff was generated primarily via the infiltration-excess (IE) mechanism (96% of events) and was largely disconnected from downslope runoff. Roughly 80% of total runoff originated from the north footslope landscape position via saturation-excess (SE) (46% of events; 62% of runoff) and IE (54% of events; 38% of runoff) mechanisms. Runoff from the north hillslope was substantially greater than the south hillslope despite their proximity, and apparently was a function of the extent of Fragipan representation. Results demonstrate the influence of subsurface soil properties (e.g. Fragipan) on surface runoff generation in variable source area hydrology settings, which could be useful for improving the accuracy of existing runoff prediction tools.
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Fragipan controls on runoff generation hydropedological implications at landscape and watershed scales
Geoderma, 2006Co-Authors: William J Gburek, Brian A Needelman, M S SrinivasanAbstract:The role of soils having a Fragipan and/or strongly contrasting clay layer in generating surface runoff, especially in the context of variable-source-area hydrology at landscape and/or watershed scales, is poorly understood. If, as preliminary research results reported here from an east-central Pennsylvania experimental watershed are showing, surface runoff from Fragipan soils can dominate a watershed's storm runoff response, it becomes imperative that hydropedologists develop tools to objectively, accurately, and routinely determine the location, extent, and hydraulic properties of these types of soils. Here, we illustrate the differing performance of non-Fragipan and Fragipan soils in producing surface runoff within an experimental watershed setting in east-central Pennsylvania (USA), demonstrating how soil mapping of Fragipan conditions enhances our ability to portray the watershed's total hydrologic performance.
A D Karathanasis - One of the best experts on this subject based on the ideXlab platform.
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Fragipan horizon fragmentation in slaking experiments with amendment materials and ryegrass root tissue extracts
The Scientific World Journal, 2014Co-Authors: A D Karathanasis, Lloyd W Murdock, Christopher J Matocha, John H Grove, Yvonne ThompsonAbstract:Slaking experiments were conducted of Fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H2O, CaCO3, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The Fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5–18.8 mm compared to the 44.2–47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. The poor efficiency of the poultry manure, ADB, and FBC treatments was attributed to their high ionic strength, while the high efficiency of the NaF, Na-hexa-metaphosphate, and rye grass root solutions to their high sodium soluble ratio (SSR). A slaking mechanism is proposed suggesting that aqueous solutions with high SSR penetrate faster into the Fragipan capillaries and generate the critical swelling pressure and shearing stress required to rupture the Fragipan into several fragments. Additional fragmentation occurs in a followup stage during which potential Si, Al, Fe, and Mn binding agents may be released into solution. Field experiments testing these findings are in progress.
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some physical and chemical factors contributing to Fragipan strength in kentucky soils
Geoderma, 1996Co-Authors: M L Norfleet, A D KarathanasisAbstract:Abstract Sixteen pedons developed in various parent materials in Kentucky were studied in order to quantify Fragipan strength and expression. The contribution to soil strength by clay, bulk density and amorphous or poorly crystalline chemical constituents in the soil fraction were also examined. The triple beam balance apparatus was successfully used to calculate strength of undisturbed, moist clods. Most argillic horizons were found to have strengths less than 40 Mg m−2, while most Fragipan horizons had strengths exceeding 60 Mg m−2. Results using this simple technique corresponded favorably to those achieved by more sophisticated geotechnical equipment for unconfined compression tests. The contribution to strength by clay and bulk density decreased as peds became less plastic and more brittle. Amorphous materials were extracted by a selective sequential procedure using acid ammonium oxalate (in the dark), citrate-dithionite-bicarbonate, and alternating acid (6 N HCl)-alkali (KOH) treatments. Additional strength in Fragipan horizons appeared to be related to an amorphous “binding” phase with a 0.5 Si (Al + Si) molar ratio, suggesting that the strength of Fragipans is more than a “clay-bridging” or density phenomenon.
R F Cullum - One of the best experts on this subject based on the ideXlab platform.
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influence of tillage on maize yield in soil with shallow Fragipan
Soil & Tillage Research, 2012Co-Authors: R F CullumAbstract:A genuine concern for landowners and other stake holders is whether conservation tillage contaminates shallow groundwater even though it greatly reduces erosion. A six-year continuous maize (Zea mays L.) study that compared yields from no-tillage (NT), reduced-tillage (RT), and conventional-tillage (CT) was conducted in the upland hills of northern Mississippi on 4–6% sloping soils overlying a shallow Fragipan. The objective was to test the hypothesis that neither no-tillage nor reduced-tillage has the same effect on maize crop as conventional-tillage on soils with a shallow water restricted layer. The study showed conservation tillage had fewer detrimental effects on the water quality in runoff and shallow groundwater and promoted more soil water for crop use during the growing season than conventional tillage. With adequate weed control, NT produced higher yields than CT on these silt loam soils due to soil water conservation. However, inadequate weed control occurred in several years of the study along with above normal rain resulting in lower NT maize yields than CT yields. Significant differences in maize yield were found for type of tillage, year, and tillage-year interaction. These differences were explained by a tillage system's ability to conserve soil water and control weeds. Other results included low sediment amounts lost from NT maize plots and insignificant free water quantities at the Fragipan's surface during the cropping season for all tillage systems. Maximum groundwater movement across the surface of the Fragipan occurred during the non-cropping season under soil profile saturation. Amount, timing, and distribution of rainfall rather than tillage system primarily influenced agrichemical movement from maize systems in this study. Some form of conservation tillage that decreases or prevents erosion will be required on sloping lands with shallow Fragipan to sustain long term continuous corn production. Information from this study provides additional guidance for making tillage and pesticide management recommendations to farmers.
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soybean yield response to tillage Fragipan depth and slope length
Transactions of the ASABE, 2000Co-Authors: R F Cullum, K C Mcgregor, C K Mutchler, J R Johnson, D L BoykinAbstract:Soybean (Glycine max) yield from continuous no-till and conventional-till systems were measured for 14 years on 12 pairs of 30.5-m long up-and-down-hill plots. The plots were located on shallow Loring (Typic Fragiudalf) silt loam soil that was underlain by a restrictive Fragipan. The no-till provided minimal erosion and the conventional-till provided excessive erosion. After the first three years, no-till yields exceeded those from conventional-till for the remainder of the study. This report deals with soybean yields that were measured from sequential 7.6-m slope segments designated as A, B, C, and D from the top to the bottom of each plot. The average Fragipan depths in the spring of 1985 were 42, 38, 37, and 30 cm in the conventional-till plots and 46, 44, 35, and 30 cm for the no-till plots for each of these respective segments. The effective slope length for runoff travel distance on segments A through D were 7.6, 15.2, 22.8, and 30.5 m, respectively. Tillage, year, effective slope length, and Fragipan depth significantly affected crop yield during the 1984 to 1997 study period. Both increase in slope length and decrease in Fragipan depth produced lower yield in both tillage systems with greater yield reduction from the conventional-till practice. An exponential equation fitted to the differences of no-till and conventional-till average yield reflected that no-till soybean yield exceeded conventional-till soybean yield by about 70% after 14 years. Predicted erosion per unit area (RUSLE, version 1.06) within segments B, C, and D for conventional-till increased 54, 85, and 108%, respectively, as compared to that within segment A. The increase was only 12.5% for no-till segments B, C, and D as compared to that within segment A. The estimated accumulated depth of soil loss from each slope segment A, B, C, and D for conventional-till represented a net decrease in Fragipan depth of about 2, 5, 8, and 10%, respectively, from 1984 to 1997. No-till produced no estimated significant changes to depth of Fragipan during the study period. The authors believe the data suggest that greater erosion from conventional-till on the lower slope segments contributed to a decrease in soil productivity on these soils.
