@article{moritz_vepraskas_ricker_2023, title={A rapid approach for ecological assessments in Carolina Bay wetlands that were previously converted to agriculture}, volume={6}, ISSN={["2624-893X"]}, DOI={10.3389/ffgc.2023.1148935}, abstractNote={Restoring wetlands is expensive, and methods for evaluating restoration condition are needed. This study developed chronosequences for use in ecological assessments (EAs) of restoration projects for Carolina Bay wetlands (CBWs) in the Southeastern US that were previously used for agriculture. An empirical method was also developed to estimate saturation levels to be used with the chronosequences. Data were collected from nine restored CBWs whose restoration ages ranged from 0 to 23 years. Plots were sorted into four Hydrologic Groups: 0–13 (Group 1), 14–50 (Group 2), 51–100 (Group 3), and 101+ (Group 4) consecutive days of saturation within 30 cm of the soil surface during the growing season. Litter thickness, tree basal area, and potential tree height were measured within a variable radius plot using a 10-factor prism across all Hydrologic Groups. Litter thickness and tree height reached an equilibrium at 15 years since restoration once crown closure occurred at the sites. In Groups 1 and 2, tree basal area reached an equilibrium at 15 years, and in Groups 3 and 4 it increased linearly to 23 and 21 years. Regression equations were developed (R2 = 0.57–0.73) to estimate saturation duration based on hydrology indicators, litter thickness, potential tree height, and soil type. These results showed that chronosequences and saturation duration would be useful for proposing performance standards in restored CBWs at time periods ranging from 5 to 23 years.}, journal={FRONTIERS IN FORESTS AND GLOBAL CHANGE}, author={Moritz, Christopher M. and Vepraskas, Michael J. and Ricker, Matthew C.}, year={2023}, month={Jun} }
 @article{moorberg_vepraskas_white_richter_2023, title={Phosphorus Fluxes in a Restored Carolina Bay Wetland Following Eight Years of Restoration}, volume={43}, ISSN={["1943-6246"]}, DOI={10.1007/s13157-023-01725-z}, abstractNote={Restoring wetlands on agricultural land can release soil phosphorus (P) to surface waters. Phosphorus is a limiting nutrient in many freshwater systems, thus restricting its release will improve surface water quality by preventing algal blooms. A P balance was used to examine how P was cycling in a Carolina Bay wetland eight years after restoration from prior-drained agricultural land. The change in soil P was evaluated between archived samples taken at restoration (2005), and eight years after restoration (2013). Measured P fluxes included atmospheric deposition, plant uptake, and loss to surface water outflow. The soil total P pool at the time of restoration was 810 kg P ha−1. No significant (α = 0.05) decrease in the soil P pool was observed over the eight years. Atmospheric deposition contributed 1.0 kg P ha−1 yr−1, plants incorporated 3.3 P ha−1 yr−1 into woody biomass and 0.4 kg P ha−1 yr−1 as forest floor litter, and 0.2 kg P ha−1 yr−1 was lost to surface waters draining the wetland. Because the loss of P to surface waters was small, and because runoff water concentrations of P declined through this period of study to concentrations below those likely to cause eutrophication (< 0.1 mg L−1), we concluded that the wetland was not contributing to the degradation of surface water quality of nearby streams following restoration. Further, isolated wetlands such as that studied may be promising sites for future wetland mitigation projects due to limited impacts on surface water quality.}, number={6}, journal={WETLANDS}, author={Moorberg, Colby J. and Vepraskas, Michael J. and White, Jeffrey G. and Richter, Daniel D.}, year={2023}, month={Aug} }
 @article{moritz_vepraskas_ricker_2023, title={Soil organic carbon changes in a Carolina Bay wetland 15 years after restoration}, volume={3}, ISSN={["1435-0661"]}, url={https://doi.org/10.1002/saj2.20521}, DOI={10.1002/saj2.20521}, abstractNote={Abstract}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Moritz, Christopher M. and Vepraskas, Michael J. and Ricker, Matthew C.}, year={2023}, month={Mar} }
 @article{moritz_vepraskas_ricker_2022, title={Hydrology and Vegetation Relationships in a Carolina Bay Wetland 15 Years after Restoration}, volume={42}, ISSN={["1943-6246"]}, url={https://doi.org/10.1007/s13157-022-01530-0}, DOI={10.1007/s13157-022-01530-0}, number={1}, journal={WETLANDS}, publisher={Springer Science and Business Media LLC}, author={Moritz, Christopher M. and Vepraskas, Michael J. and Ricker, Matthew C.}, year={2022}, month={Jan} }
 @article{kurki-fox_burchell_vepraskas_broome_2021, title={Characterizing copper and zinc content in forested wetland soils of North Carolina, USA}, volume={193}, ISSN={["1573-2959"]}, url={https://doi.org/10.1007/s10661-021-09618-6}, DOI={10.1007/s10661-021-09618-6}, abstractNote={Wetlands are often located in landscape positions where they receive runoff or floodwaters, which may contain toxic trace metals and other pollutants from anthropogenic sources. Over time, this can lead to the accumulation of potentially harmful levels of metals in wetlands soils. To assess the potential risk of Cu and Zn buildup in wetland soils in North Carolina, soil data from 88 wetlands were analyzed. In a subset of 16 wetlands, more intensive sampling was conducted. Samples were analyzed for Mehlich 3 Cu and Zn, and a subset of the samples was analyzed for total Cu and Zn. Overall, Mehlich 3 Cu and Zn were low, with mean values of 0.9 mg/kg for Cu and 3.2 mg/kg for Zn. Warning levels for Mehlich 3 Zn were only exceeded in three of the 88 sites; elevated Mehlich Cu was not observed. Total Cu and Zn were also low, with only a few sites having elevated levels; however, there was not a strong linear relationship between Mehlich 3 and total metals. Mean levels of Mehlich 3 Cu and Zn in wetlands were much lower than for human-impacted upland soils and background threshold concentrations that might be indicative of disturbance were much lower than warning levels for agricultural soils. The very low mobile Zn and Cu in most of these wetlands indicated that these metals do not pose a risk to the biota in most North Carolina wetlands, but wetlands with a direct and significant anthropogenic source of metal contamination could be exceptions.}, number={12}, journal={ENVIRONMENTAL MONITORING AND ASSESSMENT}, publisher={Springer Science and Business Media LLC}, author={Kurki-Fox, J. Jack and Burchell, Michael R., II and Vepraskas, Michael J. and Broome, Stephen W.}, year={2021}, month={Dec} }
 @misc{berkowitz_vepraskas_vaughan_vasilas_2021, title={Development and application of the Hydric Soil Technical Standard}, volume={85}, ISSN={["1435-0661"]}, url={https://doi.org/10.1002/saj2.20202}, DOI={10.1002/saj2.20202}, abstractNote={Abstract}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, publisher={Wiley}, author={Berkowitz, Jacob F. and Vepraskas, Michael J. and Vaughan, Karen L. and Vasilas, Lenore M.}, year={2021}, month={May}, pages={469–487} }
 @article{vepraskas_amoozegar_gardner_2021, title={Estimation of Saprolite Thickness Needed to Remove E. coli from Wastewater}, volume={11}, ISSN={["2076-3417"]}, url={https://doi.org/10.3390/app11052066}, DOI={10.3390/app11052066}, abstractNote={Saprolite, weathered bedrock, is being used to dispose of domestic sewage through septic system drainfields, but the thickness of saprolite needed to remove biological contaminants is unknown for most saprolites. This study developed and tested a simple method for estimating the thickness of saprolite needed below septic drainlines to filter E. coli from wastewater using estimates of the volume of pores that are smaller than the length of the coliform (≤10 μm). Particle size distribution (texture) and water retention data were obtained for 12 different saprolites from the Piedmont and Mountain regions of North Carolina (N.C.). Saprolite textures ranged from clay loam to coarse sand. The volume of pores with diameters ≤10 μm were determined by water retention measurements for each saprolite. The data were used in an equation to estimate the saprolite thickness needed to filter E. coli. The estimated saprolite thicknesses ranged from 36 cm in the clay loam to 113 cm for the coarse sand. The average thickness across all samples was 58 cm. Saprolite thickness estimates increased as silt percentage decreased and as sand percentage and in situ saturated hydraulic conductivity increased. Silt percentage may be most useful for estimating appropriate saprolite thicknesses in the field.}, number={5}, journal={APPLIED SCIENCES-BASEL}, publisher={MDPI AG}, author={Vepraskas, Michael J. and Amoozegar, Aziz and Gardner, Terrence}, year={2021}, month={Mar} }
 @article{vepraskas_skaggs_caldwell_2020, title={Method to Assess Climate Change Impacts on Hydrologic Boundaries of Individual Wetlands}, volume={40}, ISSN={["1943-6246"]}, url={https://doi.org/10.1007/s13157-019-01183-6}, DOI={10.1007/s13157-019-01183-6}, number={2}, journal={WETLANDS}, publisher={Springer Science and Business Media LLC}, author={Vepraskas, M. J. and Skaggs, R. W. and Caldwell, P.}, year={2020}, month={Apr}, pages={365–376} }
 @article{vepraskas_berkowitz_arellano_2019, title={Determining Normal Precipitation Ranges for Hydric Soil Assessments}, volume={83}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2018.09.0333}, abstractNote={
Core Ideas
Normal rainfall ranges are best defined by the 30th and 70th percentiles of historic data.
Mean ± SD produces a normal rainfall range twice as large as that of percentiles.
Mean ± SD normal rainfall will cause some upland soils to be classified as hydric soils.
Water table data collected for hydric soil and wetland identification studies require supporting analysis of rainfall normality. Water table measurements made after periods when precipitation is within a normal range are believed to represent long‐term trends, whereas data collected following periods of abnormally high precipitation represent rare events, potentially resulting in erroneous hydric soil determinations. The USDA‐NRCS currently uses two different methods to assess normal precipitation ranges; both have been used to assess hydric soils. This study compared methodologies that identify normal precipitation periods by using: (i) the range defined by the 30th and 70th percentiles observed within a 30‐yr period [i.e., the Climate Analysis for Wetlands Tables (WETS) method] and (ii) long‐term monthly mean precipitation ± one SD (i.e., the U.S. Soil Taxonomy method). Comparisons were made for 30 geographically diverse locations and soil moisture regimes. The results demonstrated that the U.S. Soil Taxonomy method yielded normal precipitation ranges approximately twice as large as those from the WETS method. As a result, the U.S. Soil Taxonomy method precluded the occurrence of drier than normal conditions in many instances and displayed increased sensitivity to infrequent high rainfall events. Three case studies evaluated the implications of method selection on hydric soil identification, demonstrating that the U.S. Soil Taxonomy method identified normal conditions more frequently than the WETS method. As a result, the adoption of the WETS method, which accounts for the non‐normal distribution of precipitation data, as the sole method to determine normal precipitation periods for hydric soil assessment is recommended.}, number={2}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Vepraskas, Michael J. and Berkowitz, Jacob F. and Arellano, Consuelo}, year={2019}, pages={503–510} }
 @article{sullivan_white_vepraskas_2018, title={Assessing Carolina Bay Wetland Restoration Risks to Downstream Water Quality by Characterizing Land Use and Stream Proximity}, volume={39}, ISSN={0277-5212 1943-6246}, url={http://dx.doi.org/10.1007/S13157-018-1095-5}, DOI={10.1007/S13157-018-1095-5}, number={3}, journal={Wetlands}, publisher={Springer Science and Business Media LLC}, author={Sullivan, Dana G. and White, Jeffrey G. and Vepraskas, Michael}, year={2018}, month={Oct}, pages={495–506} }
 @article{van groenigen_agnelli_bai_capowiez_cayuela_kögel-knabner_laird_mcbratney_morgan_nater_et al._2018, title={Citation stacking in soil science articles: our response to the open letter by concerned early-career soil scientists}, volume={328}, ISSN={0016-7061}, url={http://dx.doi.org/10.1016/J.GEODERMA.2018.03.023}, DOI={10.1016/J.GEODERMA.2018.03.023}, journal={Geoderma}, publisher={Elsevier BV}, author={van Groenigen, Jan Willem and Agnelli, Alberto and Bai, Junhong and Capowiez, Yvan and Cayuela, Mariluz and Kögel-Knabner, Ingrid and Laird, David and McBratney, Alex and Morgan, Cristine and Nater, Edward A. and et al.}, year={2018}, month={Oct}, pages={119–120} }
 @article{moorberg_vepraskas_niewhoener_2017, title={Phosphorus Dynamics Near Bald Cypress Roots in a Restored Wetland}, volume={81}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2017.07.0228}, abstractNote={
Core Ideas
Previous tree exposure to saturated conditions limited root death after ponding.
Root growth and death had no apparent effect on concentrations of Fe2+, DOC, or DTP.
Concentrations of Fe2+ were related to water table levels and redox status.
Phosphorus concentrations were controlled by iron reduction and oxidation.
Phosphorus (P) dissolution occurs commonly in wetland soils restored from agricultural land. Associated with P release are high concentrations of dissolved organic carbon (DOC) and Fe2+. This field study evaluated the effect of a fluctuating water table on the root dynamics of bald cypress (Taxodium distichum L. Rich.) to determine whether root death created soil reduction microsites, potentially contributing to P dissolution. The study site is a restored Carolina bay wetland with organic soils. Root growth and death were monitored on 16 6‐yr‐old bald cypress using minirhizotrons. Root dynamics, water table levels, and soil porewater chemistry and redox potential in the root zone were monitored for 2 yr. Soil solution samples were analyzed for Fe2+, pH, DOC, and P. High rates of root growth occurred during dry conditions, whereas root death occurred during sustained periods of saturation, particularly within 20 cm of the surface. Cyclic changes in concentrations of Fe2+, DOC, and dissolved total P (DTP) were related to water table position but not to changes in root numbers. After sustained periods of saturated conditions, redox potential decreased to 0 mV, Fe2+ increased to 1.75 mg Fe2+ L–1, and DOC increased to 350 mg L–1, resulting in peak DTP concentrations of 750 μg L–1, compared with 100 μg L–1 during dry periods. This study showed that in these high‐C soils (∼20% organic C) rooting dynamics had minimal impact on changes in P concentrations and that P dissolution was largely controlled by Fe reduction processes occurring within the C‐rich soil matrix.}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Moorberg, Colby J. and Vepraskas, Michael J. and Niewhoener, Christopher P.}, year={2017}, pages={1652–1660} }
 @article{sullivan_white_vepraskas_2017, title={Using Land-Use Change, Soil Characteristics, and a Semi-Automated On-Line GIS Database to Inventory Carolina Bays}, volume={37}, ISSN={["1943-6246"]}, DOI={10.1007/s13157-016-0842-8}, number={1}, journal={WETLANDS}, publisher={Springer Nature}, author={Sullivan, Dana G. and White, Jeffrey G. and Vepraskas, Michael J.}, year={2017}, month={Feb}, pages={89–98} }
 @article{vepraskas_2016, title={History of the concept of hydric soil}, journal={Wetland Soils: Genesis, Hydrology, Landscapes, and Classification, 2nd edition}, author={Vepraskas, M. J.}, year={2016}, pages={23–37} }
 @article{vepraskas_vaughan_2016, title={Morphological features of hydric and reduced soils}, journal={Wetland Soils: Genesis, Hydrology, Landscapes, and Classification, 2nd edition}, author={Vepraskas, M. J. and Vaughan, K. L.}, year={2016}, pages={189–217} }
 @article{vepraskas_polizzotto_faulkner_2016, title={Redox chemistry of hydric soils}, journal={Wetland Soils: Genesis, Hydrology, Landscapes, and Classification, 2nd edition}, author={Vepraskas, M. J. and Polizzotto, M. and Faulkner, S. P.}, year={2016}, pages={105–132} }
 @article{vepraskas_craft_2016, title={Second edition WETLAND SOILS Genesis, Hydrology, Landscapes, and Classification Preface}, DOI={10.1201/b18996}, journal={Wetland Soils: Genesis, Hydrology, Landscapes, and Classification, 2nd edition}, author={Vepraskas, Michael and Craft, C. B.}, year={2016}, pages={VII-} }
 @article{moorberg_vepraskas_niewoehner_2015, title={Phosphorus Dissolution in the Rhizosphere of Bald Cypress Trees in Restored Wetland Soils}, volume={79}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2014.07.0304}, abstractNote={Phosphorus release to ground or surface waters has been observed in wetlands restored from farmland. This study examined whether rhizospheres of bald cypress (Taxodium distichum L.) are a source of increased P dissolution compared with the soil matrix. The study was conducted in root-box rhizotrons filled with mineral and organic soil materials (Aeric Alaquods and Terric Haplosaprists, respectively) from a Carolina bay wetland restored from row crop agriculture. Rhizotrons were planted with bald cypress saplings or left unplanted to simulate rhizosphere and matrix conditions, respectively. Ponding was imposed for 128 d. Soil pore water was sampled in three layers (0–22, 22–41, and 41–59 cm) in each rhizotron twice monthly for dissolved total and reactive P, dissolved organic C (DOC), Fe²⁺, and redox potential (Eh). Manual root counts monitored growth and death monthly. Root death was most prevalent at 41 to 59 cm, while vigorous root growth was observed near the surface. The rhizosphere treatments exhibited increased Fe²⁺ dissolution and increased concentrations of DOC relative to matrix conditions; however, no corresponding P increase occurred. Near the surface, rhizosphere P concentrations declined below matrix concentrations after 60 d of ponding. Our results show that the rhizosphere of bald cypress did not cause higher P concentrations than matrix values for mineral and organic soils with 3.5 and 19.5% C, respectively. In addition, root growth near the surface resulted in more oxidizing conditions and/or plant uptake of P, which decreased P concentrations below matrix values.}, number={1}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Moorberg, Colby J. and Vepraskas, Michael J. and Niewoehner, Christopher P.}, year={2015}, pages={343–355} }
 @article{slusher_vepraskas_broome_2014, title={Evaluating Responses of Four Wetland Plant Species to Different Hydroperiods}, volume={43}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2013.06.0227}, abstractNote={Previous work has estimated the hydroperiod requirements (saturation duration and frequency) of wetland plant communities by modeling their hydrologic regimes in natural (never drained) wetlands for a 40-yr period. This study tested the modeled predictions in a controlled greenhouse study using tree species representing three of the plant communities plus an additional species from another community. Bald cypress ( L. Rich.), sweet bay ( L.), pond pine ( Michx.), and swamp chestnut oak ( Nutt.) were grown under three hydroperiods (continuously ponded for 100 d, intermittently ponded for 14 d, and unsaturated) in loamy sand and sapric (organic) materials. Bald cypress (representing a Nonriverine Swamp Forest community) adapted well to 100 d of ponding by producing lateral roots near the soil surface and aerenchyma tissue in roots and stem. Sweet bay (Bay Forest community) also adapted well to 100 d of ponding by producing adventitious roots on the submerged portion of the stem. Pond pine (Pond Pine Woodland) and swamp chestnut oak (Nonriverine Wet Hardwood Forest) were intolerant of 100 d of ponded conditions. Seventy-five percent of the pond pine seedlings and 87% of the swamp chestnut oak seedlings died in the continuously ponded treatment level, whereas 100% of the bald cypress and 88% of the sweet bay seedlings survived. Results from this study suggest that modeled long-term hydroperiods of natural wetland plant communities can be used for restoration of these communities.}, number={2}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Slusher, C. E. and Vepraskas, M. J. and Broome, S. W.}, year={2014}, pages={723–731} }
 @article{abit_vepraskas_duckworth_amoozegar_2013, title={Dissolution of phosphorus into pore-water flowing through an organic soil}, volume={197}, ISSN={["1872-6259"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84873020656&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2012.12.012}, abstractNote={Understanding dissolution and transport of phosphorus (P) from organic soils in agricultural fields and restored wetlands is critical for devising management strategies to mitigate P losses. The objective of this study was to evaluate the dissolution of P in water flowing through the vadose zone-shallow ground water continuum of an organic soil. Three 90 cm × 50 cm × 8 cm flow cells were uniformly packed with organic soil material from a Ponzer muck (Terric Haplosaprists) collected from an area that had been in agricultural production for at least 30 years. The packed flow cells were instrumented with soil solution samplers and platinum-tipped redox electrodes at approximately 5 cm below a simulated water table (WT), and in the capillary fringe (CF) at approximately 5 and 20 cm above the WT to collect soil solution and monitor the reduction potential (Eh), respectively. Distilled water was continuously supplied at constant rates of 1.2, 2.4, and 3.6 L d− 1 to one end, and drained at the other end of the flow cells while maintaining a WT at 12 cm above the bottom of the midpoint of each flow cell. Phosphorus concentration in the outflow solution was consistently above the USEPA water quality criteria of 0.1 mg L− 1. Changes in pore-water velocity did not alter the amounts of P leached within the time frame of the experiment. Dissolved phosphorus concentrations at both 5 cm below and 5 cm above the WT were significantly higher than at 20 cm above the WT. This observation indicated that P that leached out of the flow cells was not only from the saturated zone but also from the lower part of the CF. These results suggest that controlling the height of the WT to limit saturation of P enriched surficial soils, while considering the contribution of the CF, may be an effective management tool for limiting P export from restored wetland sited on former agricultural fields.}, journal={GEODERMA}, author={Abit, Sergio M. and Vepraskas, Michael J. and Duckworth, Owen W. and Amoozegar, Aziz}, year={2013}, month={Apr}, pages={51–58} }
 @article{moorberg_vepraskas_niewoehner_2013, title={Dynamics of P dissolution processes in the matrix and rhizospheres of bald cypress growing in saturated soil}, volume={202}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2013.03.017}, abstractNote={Phosphorus release to ground or surface waters is commonly observed in wetlands that were restored on previously drained and farmed land, but the precise location of where the P is dissolved within the soil is unknown. This study compared the concentration of dissolved P in both the rhizospheres and soil matrix under saturated conditions. Experiments were conducted in rhizotrons (glass-walled boxes) which were filled with Ap horizon material from an Aeric Alaquod in a restored wetland. Phosphorus release was monitored from the rhizospheres of bald cypress roots (Taxodium distichum, L.), and an unplanted control representing the soil matrix. The rhizotrons were saturated for 120 days, and soil water was collected twice monthly at three depths. Numbers of live and dead roots were determined monthly. Following saturation, vigorous root growth was observed near the surface (0 to 22 cm depth) throughout the 120 days saturation period, while up to 30% of the roots in the lower layer (41 to 59 cm depth) died after 20 days of saturation. Rhizosphere processes did not increase P concentrations in the soil solution compared to the matrix controls. In the top layer of the planted treatment dissolved total P concentrations were 3.5 times lower than matrix concentrations (peak DTP of 700–900 μg P L− 1””) due to oxygen loss by root aerenchyma. Significantly larger amounts of dissolved organic C and Fe2 + were found in the rhizospheres than the matrix. Dissolved total P concentrations in the rhizosphere were equal to DTP concentrations in the matrix during the first 54 days of saturation, but lower than those of the matrix thereafter, most likely due to plant uptake. These findings indicate that under saturated conditions plant rhizospheres do not cause more P to be released to the soil water over that of the matrix, and may contain lower amounts of P than the soil matrix due to plant uptake. These results pertain to soils having an organic C concentration of at least 26 g kg− 1 or higher.}, journal={GEODERMA}, author={Moorberg, Colby J. and Vepraskas, Michael J. and Niewoehner, Christopher P.}, year={2013}, month={Jul}, pages={153–160} }
 @article{ewing_vepraskas_broome_white_2012, title={Differences in Wetland Soil Chemical Soil Properties after 15, 20, and 30 Years of Drainage and Agricultural Production}, volume={179-180}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2012.02.018}, abstractNote={When wetland restoration occurs on land previously used for crop production, residual nutrients can cause undesirable plant communities to grow, and increased solubility of excess P may contribute to eutrophication of surface waters. This study assessed how agricultural production in a drained wetland during 15, 20, and 30 yr periods changed morphological and chemical soil properties as compared to natural wetland soils not used for agriculture. The drained wetland, Juniper Bay, is a Carolina bay located in southeastern North Carolina. Three relatively undisturbed Carolina bays with soil types similar to those in Juniper Bay were selected as reference wetlands to compare soil properties. Three general soil types were identified in all the Carolina bays based on thickness of the organic surface layer: 1) organic soils (Histosols), 2) soils with histic epipedons, and 3) mineral soils. The surface horizon of all three soil types at Juniper Bay where crop production had occurred had significantly greater amounts of extractable P, Ca, Mg, Mn, Zn and Cu, along with higher base saturation and pH than soils in the reference bays. Greater length of time in crop production resulted in significant differences in soil chemical properties with depth. For soils farmed for 15 years, significant increases in extractable nutrients occurred only in the topsoil within approximately 20 cm of the soil surface. After 30 years of crop production, significantly increased amounts of extractable nutrients were present to depths of approximately 1 m. Residual nutrients and the higher pH of previously farmed wetland soils are likely to affect restoration of natural plant communities, which consist of plant species adapted to nutrient poor acid soils. Increased solubility of residual P when wetland hydrology and anaerobic soil conditions are restored may degrade water quality. These factors should be considered in planning wetland restoration projects.}, journal={Geoderma}, publisher={Elsevier BV}, author={Ewing, J. and Vepraskas, M.J. and Broome, S.W. and White, J.G.}, year={2012}, pages={73–80} }
 @article{abit_amoozegar_vepraskas_niewoehner_2012, title={Soil and hydrologic effects on fate and horizontal transport in the capillary fringe of surface-applied nitrate}, volume={189}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2012.05.029}, abstractNote={Substantial horizontal solute transport has been demonstrated to occur in the capillary fringe (CF) above a flowing ground water, yet the importance of the CF for solute movement has generally been ignored. This study was conducted to evaluate the fate and horizontal transport of surface-applied nitrate (NO3−) in the CF under simulated hydrologic conditions that varied flow rates. Two soils of different organic carbon content were packed in separate 240-cm long, 60-cm high and 25-cm thick flow cells. A simulated water table (WT) was established at 20 cm above the bottom of each flow cell and different pore-water velocities across the flow cell were simulated while a solution containing NO3− and bromide (Br−) was continuously applied over a small area on the surface of the soil in the flow cell. Soil solution samples were collected from two depths below the WT and two depths within the CF above the WT at four locations along the flow cell. Subsurface horizontal transport of surface-applied NO3− tended to occur exclusively in the CF as the pore-water velocity was increased. In the flow cell with soil having a small amount of organic carbon (0.3 g kg− 1), normalized concentration of NO3− and Br− remained very comparable at all monitoring locations above and below the WT. Nitrate loss via denitrification in this case was not observed as conditions were oxidizing. In flow cells with soils having an organic carbon content of 35 g kg− 1, some Br− was detected below the WT while NO3− was essentially absent. Conditions below the WT favored NO3− loss via denitrification as reflected by very low redox potentials (< 250 mV). These results suggest that collection of samples from the CF should be considered when monitoring subsurface fate and transport of surface-applied NO3− in locations with laterally moving shallow ground water.}, journal={GEODERMA}, author={Abit, Sergio M., Jr. and Amoozegar, Aziz and Vepraskas, Michael J. and Niewoehner, Christopher P.}, year={2012}, month={Nov}, pages={343–350} }
 @article{taggart_heitman_shi_vepraskas_2012, title={Temperature and Water Content Effects on Carbon Mineralization for Sapric Soil Material}, volume={32}, ISSN={0277-5212 1943-6246}, url={http://dx.doi.org/10.1007/S13157-012-0327-3}, DOI={10.1007/S13157-012-0327-3}, number={5}, journal={Wetlands}, publisher={Springer Science and Business Media LLC}, author={Taggart, Matthew and Heitman, J. L. and Shi, Wei and Vepraskas, Michael}, year={2012}, month={Jul}, pages={939–944} }
 @article{caldwell_vepraskas_gregory_skaggs_huffman_2011, title={Linking plant ecology and long-term hydrology to improve wetland restoration success}, volume={54}, DOI={10.13031/2013.40662}, abstractNote={Although millions of dollars are spent restoring wetlands, failures are common, in part because the planted vegetation cannot survive in the restored hydrology. Wetland restoration would be more successful if the hydrologic requirements of wetland plant communities were known so that the most appropriate plants could be selected for the range of projected hydrology at the site. Here we describe how hydrologic models can be used to characterize the long-term hydrology of wetland plant communities, and we show how these results can be used to define wetland design criteria. In our study, we quantified differences in long-term (40-year) hydrologic characteristics of the pond pine woodland (PPW), nonriverine swamp forest (NRSF), high pocosin (HP), and bay forest (BF) plant communities native to the North Carolina Coastal Plain. We found that the median water level was 8 cm below the land surface in PPW and 9, 2, and 8 cm above the land surface for NRSF, HP, and BF, respectively. When the land surface was inundated, the median duration of inundation was 91 d year-1 for PPW and 317, 243, and 307 d year-1 for NRSF, HP, and BF, respectively. Our models suggested that the PPW received an average of 15% of its water input from groundwater inflow, whereas the other communities we modeled did not appear to receive groundwater inflow. Using these results and soil organic layer thickness, we developed and propose design criteria linking soil, vegetation, and hydrology parameters that should contribute to improved restoration success.}, number={6}, journal={Transactions of the ASABE}, author={Caldwell, P. V. and Vepraskas, Michael and Gregory, J. D. and Skaggs, R. W. and Huffman, R. L.}, year={2011}, pages={2129–2137} }
 @article{taggart_heitman_vepraskas_burchell_2011, title={Surface shading effects on soil C loss in a temperate muck soil}, volume={163}, ISSN={0016-7061}, url={http://dx.doi.org/10.1016/j.geoderma.2011.04.020}, DOI={10.1016/j.geoderma.2011.04.020}, abstractNote={Histosols are a huge reservoir for C, covering < 1% of the world's land surface but storing up to 12% of total soil C. Thorough comprehension of factors controlling the rate of soil C loss from Histosols is critical for proper management of these C sinks. Two experiments evaluated how formerly cultivated, warm-climate Histosols undergoing wetland restoration respond to decreases in soil temperatures via vegetative shading, under different water table conditions. We compared temperature and soil CO2 efflux differences from intact soil cores under three levels of light reduction in a greenhouse: 0%, 70%, and 90%. Soil in full sun was consistently warmer and showed higher efflux rates than 70% and 90% shade treatments: 4.132, 3.438, and 2.054 μmol CO2 m−2 s−1, respectively. Shade treatments reached peak efflux rates at similar water potential, −2 to − 4 kPa. A field experiment subjected in-situ soil to full sun, 70% light reduction, and light reduction from naturally occurring herbaceous vegetation. Shade treatment effects on soil temperature and C mineralization were evident throughout the growing season. Vegetative shade effects on soil temperature were greatest in August and September when soil under vegetation was 5–11 °C cooler than unshaded soil. Soil CO2 efflux was correlated strongly with soil temperature; daily efflux rates were consistently highest from unshaded soil. Efflux across treatments showed a strong seasonal correlation to soil moisture, increasing as soil dried in response to water table decline. Soil water potential was unaffected by shade treatment, suggesting temperature effects were solely responsible for efflux differences between treatments. All results confirm that surface shading has a strong influence on soil temperatures and C mineralization rates. Management to enhance vegetative shading in wetland restoration projects may be an effective strategy for slowing soil C losses and promoting soil C sequestration when O2 is not limiting.}, number={3-4}, journal={Geoderma}, publisher={Elsevier BV}, author={Taggart, Matthew J. and Heitman, Joshua L. and Vepraskas, Michael J. and Burchell, Michael R.}, year={2011}, month={Jul}, pages={238–246} }
 @article{hesterberg_duff_dixon_vepraskas_2011, title={X-ray Microspectroscopy and Chemical Reactions in Soil Microsites}, volume={40}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79956072636&partnerID=MN8TOARS}, DOI={10.2134/jeq2010.0140}, abstractNote={Soils provide long-term storage of environmental contaminants, which helps to protect water and air quality and diminishes negative impacts of contaminants on human and ecosystem health. Characterizing solid-phase chemical species in highly complex matrices is essential for developing principles that can be broadly applied to the wide range of notoriously heterogeneous soils occurring at the earth's surface. In the context of historical developments in soil analytical techniques, we describe applications of bulk-sample and spatially resolved synchrotron X-ray absorption spectroscopy (XAS) for characterizing chemical species of contaminants in soils, and for determining the uniqueness of trace-element reactivity in different soil microsites. Spatially resolved X-ray techniques provide opportunities for following chemical changes within soil microsites that serve as highly localized chemical micro- (or nano-)reactors of unique composition. An example of this microreactor concept is shown for micro-X-ray absorption near edge structure analysis of metal sulfide oxidation in a contaminated soil. One research challenge is to use information and principles developed from microscale soil chemistry for predicting macroscale and field-scale behavior of soil contaminants.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Hesterberg, Dean and Duff, Martine C. and Dixon, Joe B. and Vepraskas, Michael J.}, year={2011}, month={May}, pages={667–678} }
 @article{dimick_stucky_wall_vepraskas_wentworth_arellano_2010, title={Plant-Soil-Hydrology Relationships in Three Carolina Bays in Bladen County, North Carolina}, volume={75}, ISSN={["1938-4386"]}, DOI={10.2179/09-063.1}, abstractNote={Abstract This study provides quantitative ecological targets for restoring degraded peat-based Carolina Bays in the Carolina Flatwoods Ecoregion. Cluster analysis of vegetation data from three Carolina Bay reference sites in Bladen County, North Carolina, indicated four plant communities present: pond pine (Pinus serotina) woodland, non-riverine swamp forest dominated by swamp gum (Nyssa biflora), high pocosin dominated by evergreen shrubs with scattered pond pine, and bay forest dominated by loblolly bay (Gordonia lasianthus). We classified bay soils according to surface organic layer thickness (OLT) into mineral, histic, shallow organic, and deep organic types. We monitored the water table of each soil type in one bay throughout one growing season. The soil types with corresponding water table regimes were: mineral (9.4 cm mean OLT with a rooting zone water table [RZWT] 39% of the monitoring period), histic (27.5 cm OLT and 76% RZWT), shallow organic (63.9 cm OLT and 84% RZWT), and deep organic (102.5 cm OLT and 57% RZWT). Pearson residual analysis and correspondence analysis revealed that pond pine woodland was positively associated with mineral and histic soils, non-riverine swamp forest with shallow organic soil, bay forest with deep organic soil, and high pocosin with deep organic soil. We concluded that peat-based Carolina Bay restoration in the Carolina Flatwoods Ecoregion should be gauged against reference data which suggests: 1) pond pine woodland be established on mineral and histic soils; 2) non-riverine swamp forest be established on shallow organic soils; and 3) high pocosin and bay forest be established on deep organic soils.}, number={4}, journal={CASTANEA}, author={Dimick, Britta P. and Stucky, Jon M. and Wall, Wade and Vepraskas, Michael J. and Wentworth, Thomas R. and Arellano, Consuello}, year={2010}, month={Dec}, pages={407–420} }
 @article{vepraskas_heitman_austin_2009, title={Future directions for hydropedology: quantifying impacts of global change on land use}, volume={13}, ISSN={["1607-7938"]}, DOI={10.5194/hess-13-1427-2009}, abstractNote={Abstract. Hydropedology is well positioned to address contemporary issues resulting from climate change. We propose a six-step process by which digital, field-scale maps will be produced to show where climate change impacts will be greatest for two land uses: a) home sites using septic systems, and b) wetlands. State and federal laws have defined critical water table levels that can be used to determine where septic systems will function well or fail, and where wetlands are likely to occur. Hydrologic models along with historic rainfall and temperature data can be used to compute long records of water table data. However, it is difficult to extrapolate such data across land regions, because too little work has been done to test different ways for doing this reliably. The modeled water table data can be used to define soil drainage classes for individual mapping units, and the drainage classes used to extrapolate the data regionally using existing digital soil survey maps. Estimates of changes in precipitation and temperature can also be input into the models to compute changes to water table levels and drainage classes. To do this effectively, more work needs to be done on developing daily climate files from the monthly climate change predictions. Technology currently exists to use the NRCS Soil Survey Geographic (SSURGO) Database with hydrologic model predictions to develop maps within a GIS that show climate change impacts on septic system performance and wetland boundaries. By using these maps, planners will have the option to scale back development in sensitive areas, or simply monitor the water quality of these areas for pathogenic organisms. The calibrated models and prediction maps should be useful throughout the Coastal Plain region. Similar work for other climate-change and land-use issues can be a valuable contribution from hydropedologists.
                    }, number={8}, journal={HYDROLOGY AND EARTH SYSTEM SCIENCES}, author={Vepraskas, M. J. and Heitman, J. L. and Austin, R. E.}, year={2009}, pages={1427–1438} }
 @article{sumner_vepraskas_kolka_2009, title={METHODS TO EVALUATE NORMAL RAINFALL FOR SHORT-TERM WETLAND HYDROLOGY ASSESSMENT}, volume={29}, ISSN={["1943-6246"]}, DOI={10.1672/09-026d.1}, abstractNote={Identifying sites meeting wetland hydrology requirements is simple when long-term (> 10 years) records are available. Because such data are rare, we hypothesized that a single-year of hydrology data could be used to reach the same conclusion as with long-term data, if the data were obtained during a period of normal or below normal rainfall. Long-term (40–45 years) water-table and rainfall data were obtained for two sites in North Carolina (with modeling), and one site in Minnesota (direct measurements). Single-year wetland hydrology assessments were made using two-rainfall assessment procedures recommended by the U.S. Army Corps of Engineers for their Wetland Hydrology Technical Standard, and two other rainfall assessment methods that were modifications of those procedures. Percentages of years meeting wetland-hydrology conditions during normal or drier than normal periods were identified for each plot with each rainfall assessment method. Although the wetland hydrology criterion was met in over 90% of the years across all plots using the long-term records, the four assessment techniques predicted the criterion was met in 41–81% of the years. Based on our results, we recommend that either the Direct Antecedent Rainfall Evaluation Method, or its modified version, be used for wetland hydrology assessment.}, number={3}, journal={WETLANDS}, author={Sumner, Jaclyn P. and Vepraskas, Michael J. and Kolka, Randall K.}, year={2009}, month={Sep}, pages={1049–1062} }
 @article{abit_amoozegar_vepraskas_niewoehner_2008, title={Fate of nitrate in the capillary fringe and shallow groundwater in a drained sandy soil}, volume={146}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2008.05.015}, abstractNote={It is commonly assumed that nitrate (NO3−) and other anions entering the soil move downward through the vadose zone, and then move horizontally in the groundwater. Recent laboratory studies, however, indicate that water movement and transport of pollutants can also take place in the capillary fringe (CF) above the water table (WT). This field study evaluated the fate of NO3− in the CF and shallow groundwater (SGW) for a sandy soil (Aeric Alaquod) with shallow water table. Ten L of a solution containing approximately 18 mmol L− 1 nitrate [2.66 g L− 1 Mg(NO3)2] and 77 mmol L− 1 bromide (9.12 g L− 1 KBr) were applied to the soil above the CF. The movement of both NO3− and Br− was monitored for 84 days by using tension lysimeters installed at depths between 45 and 105 cm at radial distances of 20, 60, 120, 220 and 320 cm from the application point. Nitrate and Br− plumes that entered the CF from the unsaturated zone moved horizontally in the CF until both species were partially carried into the groundwater by the fluctuating WT following rain events. Normalized concentrations of NO3−N and Br− remained comparable as they moved horizontally in the CF up to 320 cm from the tracer application spot. However, below the WT the detected normalized concentration of Br− was higher than that for NO3− indicating nitrate loss, perhaps due to denitrification. When monitoring subsurface NO3−, solely relying on collection of groundwater samples may lead to an underestimation of the extent of NO3− contamination and transport in the subsurface.}, number={1-2}, journal={GEODERMA}, author={Abit, Sergio M. and Amoozegar, Aziz and Vepraskas, Michael J. and Niewoehner, Christopher P.}, year={2008}, month={Jul}, pages={209–215} }
 @article{severson_lindbo_vepraskas_2008, title={Hydropedology of a coarse-loamy catena in the lower Coastal Plain, NC}, volume={73}, ISSN={["0341-8162"]}, DOI={10.1016/j.catena.2007.09.001}, abstractNote={The identification of the depth of seasonal saturation in soils is critical for a multitude of land uses including the siting and design of septic systems and delineation of wetlands. Often 2 chroma redox depletions are used to make this determination; however, other redoximorphic features are also related to saturation. With increasing land use intensities and environmental concerns it is important to understand exactly how redoximorphic features (RMFs) relate to saturation. The objective of this research is to relate RMFs to saturation in a coarse-loamy catena in the lower coastal plain in North Carolina. A relatively undisturbed site in eastern NC was identified and three transects were instrumented with recording wells, redox probes and thermocouples. A rain gauge was also located at the site. In all the soils investigated, ≤ 2 chroma redox depletions related to an average cumulative annual saturation percentage (CSP) of 15%. However, the ≤ 2 chroma redox depletions indicated a larger CSP in the MWD soils (19%) as compared to the SWPD soils (11%). This suggests that ≤ 2 chroma redox depletions do not mean the same thing in all soils. Regulations that rely on this single feature may be identifying different degrees of saturation and thus may have a varying implication to wastewater treatment and water quality.}, number={2}, journal={CATENA}, author={Severson, E. D. and Lindbo, D. L. and Vepraskas, M. J.}, year={2008}, month={Apr}, pages={189–196} }
 @article{lin_bouma_owens_vepraskas_2008, title={Hydropedology: Fundamental issues and practical applications}, volume={73}, ISSN={["1872-6887"]}, DOI={10.1016/j.catena.2007.09.004}, number={2}, journal={CATENA}, author={Lin, Henry and Bouma, Johan and Owens, Phillip and Vepraskas, Michael}, year={2008}, month={Apr}, pages={151–152} }
 @article{vepraskas_caldwell_2008, title={Interpreting morphological features in wetland soils with a hydrologic model}, volume={73}, ISSN={["1872-6887"]}, DOI={10.1016/j.catena.2007.07.005}, abstractNote={Wetlands in the United States are protected by law and are identified by their hydric soils, wetland hydrology, and vegetation. Hydric soils are easily identified by color characteristics termed hydric soil field indicators, that form under saturated and anaerobic conditions, but wetland hydrology is difficult to assess. This study determines how often seven hydric soil field indicators met wetland hydrology requirements which require a water table be within 30 cm of the surface for 14 days or more during the growing season in over half the years. Studies were conducted at five sites in North Carolina in both wetland and upland plots. Soils ranged from Aquic Paleudults to Typic Haplosaprists across all sites. The water-table simulation model DRAINMOD was calibrated to soil conditions in individual plots. Long-term rainfall data were used with the calibrated models to compute 40 years of daily water table data to represent both wet and dry years. It was found that the hydric soils with field indicators composed of organic materials in layers over 20 cm thick (Histosol and Histic epipedon field indicators) met wetland hydrology requirements each year, and in addition were ponded with water for periods between 67 to 139 days on average each year during the growing season. Plots in mineral soils having the Dark Surface (S7) indicator as well as the Sandy Mucky Mineral (S1) indicator also met the saturation requirements for wetland hydrology every year, and were ponded for only 3 days per year on average. Other mineral soils with an Umbric Surface (F13) or a Depleted Matrix (F3) field indicator met wetland hydrology requirements in approximately 95% of the years, and had water tables within 30 cm of the surface for 40 days per year on average. The Redox Depressions (F8) field indicator occurred in a small depression that was saturated for 87% of the year for periods averaging approximately 30 days. These results showed that hydric soil field indicators can be calibrated to long-term water table data that will allow precise assessments of wetland hydrology on-site.}, number={2}, journal={CATENA}, author={Vepraskas, M. J. and Caldwell, P. V.}, year={2008}, month={Apr}, pages={153–165} }
 @article{abit_amoozegar_vepraskas_niewoehner_2008, title={Solute transport in the capillary fringe and shallow groundwater: Field evaluation}, volume={7}, DOI={10.2136/vzj.2007.0102}, number={3}, journal={Vadose Zone Journal}, author={Abit, S. M. and Amoozegar, Aziz and Vepraskas, Michael and Niewoehner, C. P.}, year={2008}, pages={890–898} }
 @article{caldwell_vepraskas_gregory_2007, title={Physical properties of natural organic soils in Carolina Bays of the southeastern United States}, volume={71}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2006.0108}, abstractNote={Hydrologic models are useful tools for designing wetland restoration projects, but they are difficult to use for sites with natural organic soils because few soil property data are available for these soils. The objective of this study was to measure the physical properties of organic soils needed to calibrate hydrologic models of three natural Carolina Bay wetlands in the southeastern USA. Undisturbed soil cores were collected at each site for laboratory measurement of saturated hydraulic conductivity, soil water characteristic curves, bulk density, particle density, and total porosity. Field measurements of saturated hydraulic conductivity were also made. The Oi, Oe, and Oa horizons in the natural organic soils had similar bulk densities (0.16 g cm -3 ), total porosities (0.90 cm 3 cm -3 ), and particle densities (1.50 g cm -3 ). However, field-measured saturated hydraulic conductivities decreased as the level of decomposition increased, going from 45 to 7.1 to 1.5 cm h -1 for the Oi, Oe, and Oa horizons, respectively. Soil water characteristic data revealed an abundance of large pores (>0.3 mm) in the Oi horizons, which likely explains their high saturated hydraulic conductivity relative to the Oe and Oa horizons, which had fewer large pores. Using the data collected in this study, mathematical relationships were developed to predict the total porosity and the saturated hydraulic conductivity of these organic soils based on more easily obtainable data, such as bulk density and the organic horizon type.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Caldwell, P. V. and Vepraskas, M. J. and Gregory, J. D.}, year={2007}, pages={1051–1057} }
 @article{caldwell_vepraskas_skaggs_gregory_2007, title={Simulating the water budgets of natural Carolina bay wetlands}, volume={27}, ISSN={["0277-5212"]}, DOI={10.1672/0277-5212(2007)27[1112:stwbon]2.0.co;2}, abstractNote={Wetland restoration projects attempt to recreate the hydrology found in natural wetlands, but little is known of the water budgets associated with wetlands in their natural state. The objective of this study was to compute the water budgets of three natural Carolina bay wetlands in Bladen County, North Carolina, USA. DRAINMOD models of various locations in the bays were calibrated with measured water table depths over a 2-yr period using inputs of rainfall, air temperature, and soil physical properties. The models were successful in simulating water table depths at all well locations during the calibration period with average absolute deviations between simulated and measured water table depths of approximately 4 cm. Measured and simulated data revealed very shallow (< 0.1 m) water table depths at all of the bays. Groundwater inflow was a significant component of the water balance at locations near the perimeters of the bays, ranging from 3%–26% of the total water input for these sites during the study period. A semi-confined aquifer below one of the bays was likely the source of groundwater inflow for that bay. Meanwhile, locations near the centers of the bays did not have groundwater inflow as an input to their water budgets. Groundwater outflow for the centers of the bays ranged from 2%–21% of rainfall. Areas near the perimeters of the bays were recharge, discharge, or flow-through wetlands depending on hydrologic conditions at the sites. Areas near the centers of the bays exhibited characteristics of recharge wetlands only. These results were consistent across the three Carolina bays studied, and can be used to better understand the hydrology of natural Carolina bays, improving the success of restoration projects of similar sites.}, number={4}, journal={WETLANDS}, author={Caldwell, Peter V. and Vepraskas, Michael J. and Skaggs, R. Wayne and Gregory, James D.}, year={2007}, month={Dec}, pages={1112–1123} }
 @article{fiedler_vepraskas_richardson_2007, title={Soil redox potential: Importance, field measurements, and observations}, volume={94}, ISBN={["978-0-12-374107-3"]}, ISSN={["2213-6789"]}, DOI={10.1016/s0065-2113(06)94001-2}, abstractNote={Reduction and oxidation measurements create important data for analysis of wet soils. These measurements are actually recordings of voltage (EH) over time between a reference electrode and a sensor electrode inserted into a soil. The sensor electrodes are usually made of platinum wire (Pt electrode). Hydric soils require a period of reduction, and these measures can provide the length of time that the reduction process is occurring. The voltage results from an exchange of electrons between a redox couple such as ferrous and ferric iron during the process of reduction and oxidation. In soils that have fluctuating wet and dry conditions, wide fluctuations in Eh occur. Micro site differences complicate these measurements in that anaerobes may be active and at 1‐cm away they are completely inactive. The ferrous–ferric iron couple usually dominates these measurements but other couple often contributes complicating the measurements and interpretations of the data. Reference electrodes are often fine for laboratory work but are not rugged enough for the field. In this chapter, suggestions for improvement are discussed. Field‐measuring equipment and the Pt electrode are also sensitive and subject to problems that often lead to spurious results in the field. These problems are discussed at length. Iron‐coated tubes and other methods of establishing redox conditions are relatively recent and are discussed, also.}, journal={ADVANCES IN AGRONOMY, VOL 94}, author={Fiedler, Sabine and Vepraskas, Michael J. and Richardson, J. L.}, year={2007}, pages={1–54} }
 @article{szuch_white_vepraskas_doolittle_2006, title={Application of ground penetrating radar to aid restoration planning for a drained Carolina Bay}, volume={26}, ISSN={["1943-6246"]}, DOI={10.1672/0277-5212(2006)26[205:aogprt]2.0.co;2}, abstractNote={Clayey subsurface strata in precipitation-driven wetlands act as aquitards that retain water and can affect wetland hydrology. If the aquitard layers have been cut through by drainage ditches, then restoring wetland hydrology to such sites may be more difficult because of the need to fill ditches completely with low hydraulic conductivity material. Ground penetrating radar (GPR) surveys were conducted to determine the depth and continuity of shallow clay layers and identify those that have been pierced by drainage ditches at Juniper Bay, a 300-ha drained Carolina bay in North Carolina, USA that will be restored. Carolina bays are a wetland type that occur as numerous, shallow, oval-shaped depressions along the Atlantic Coastal Plain. The GPR interpretations found that moderately fine-textured (clay loam, sandy clay loam, silty clay loam) and fine-textured (sandy clay, silty clay, clay) aquitards underlay coarser-textured horizons in most of the bay at an average depth of 1.6 m. Extensive ground truthing showed that, on average, GPR predicted the depth to these aquitards to within 16% of their actual depth. An atypical GPR reflection in the southeast sector of the bay was interpreted as a fluvial deposit without aquitards until a depth of 3 to 5 m. This area may require different restoration strategies than the rest of the bay. By comparing the depths of aquitards and drainage ditches, several areas were identified as likely locations of ditch-induced aquitard discontinuity that may require filling or lining of suspect ditches to prevent potential water losses if there are downward hydraulic gradients. Cost estimates by two professional firms indicated that GPR could provide large volumes of data with cost and time efficiency. GPR surveys are proposed as a useful tool for characterizing potential wetland restoration sites on the Atlantic Coastal Plain and other regions with similar soils.}, number={1}, journal={WETLANDS}, author={Szuch, RP and White, JG and Vepraskas, MJ and Doolittle, JA}, year={2006}, month={Mar}, pages={205–216} }
 @article{vepraskas_richardson_tandarich_2006, title={Dynamics of redoximorphic feature formation under controlled ponding in a created riverine wetland}, volume={26}, ISSN={["1943-6246"]}, DOI={10.1672/0277-5212(2006)26[486:dorffu]2.0.co;2}, abstractNote={Hydric soils are identified on-site using morphological features called “field indicators”. It is not known how long it takes for these indicators to form, nor whether they occur in created wetlands inundated for approximately 5% of the growing season, which is the minimum duration needed to meet wetland hydrology requirements. This study evaluated formation of redoximorphic features and hydric soil field indicators under field conditions following controlled, short-term floods that produced ponding events. A flood plain was constructed along an artificial stream channel (100-m long) where flooding was controlled by dams at each end of the channel. Floodwaters inundated soils on the flood plain nine times over a 3-year period. Ponded water was kept on the soils for periods ranging from 4 to 44 days. During ponding events, Fe2+ concentrations were approximately 1 to 4 mg/L, which indicated that the soils were anaerobic and undergoing Fe reduction. Redox depletions formed in A horizons following a single 7-day ponding event. Abundance of depletions increased from 2% to an average of 15% after nine ponding events. Most depletions were approximately 1 cm in diameter and had Munsell hues of 2.5Y and 5Y, values of 4, and chromas of 2 or less. The depletions appeared to form in place by loss of both Fe and C. Hydric soil field indicators developed in all plots after nine ponding events over a 3-year period and included the depleted matrix, redox dark surface, and a variant of the depleted dark surface. All indicators formed by a reduction and/or oxidation of Fe.}, number={2}, journal={WETLANDS}, author={Vepraskas, Michael J. and Richardson, Jimmie L. and Tandarich, John P.}, year={2006}, month={Jun}, pages={486–496} }
 @article{ewing_vepraskas_2006, title={Estimating primary and secondary subsidence in an organic soil 15, 20, and 30 years after drainage}, volume={26}, ISSN={["1943-6246"]}, DOI={10.1672/0277-5212(2006)26[119:epassi]2.0.co;2}, abstractNote={Wetland hydrology can be restored to soils that have been drained by plugging ditches to return the water table to its original elevation. Organic soils subside after drainage, and when ditches are plugged the restored water table may rise above the soil surface, killing newly planted vegetation. This study developed a method to estimate amounts of primary (settling) and secondary (oxidation) subsidence that could be applied to any organic soil. Primary subsidence was estimated from differences in bulk density between the drained and representative undrained sites. Secondary subsidence was estimated from accumulation of sand in the surface (Oap) horizons and changes in bulk density between oxidized and unoxidized organic horizons. Total subsidence was the sum of primary and secondary subsidence. Bulk density, particle size, and organic carbon data were gathered from one drained (Juniper Bay) and three undrained Carolina bay wetlands. Juniper Bay was drained with a network of ditches in three stages, 15, 20, and 30 years ago. Mean total subsidence was not significantly different (0.10 level) over time and averaged 121 cm for the three drainage periods. The mean rate of primary subsidence across the three drainage periods was 4 cm yr−1, while secondary subsidence was approximately 2 cm yr−1. Subsidence values were variable across Juniper Bay and were not related to distance from a field ditch. Restoration of the hydrology in Juniper Bay to predrainage water-table elevations could result in a water table that is > 1 m above the existing soil surface.}, number={1}, journal={WETLANDS}, author={Ewing, JM and Vepraskas, MJ}, year={2006}, month={Mar}, pages={119–130} }
 @article{vepraskas_huffman_kreiser_2006, title={Hydrologic models for altered landscapes}, volume={131}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2005.03.010}, abstractNote={Understanding the hydrology of soils that have been drained is necessary for wetland restoration and in determining whether redoximorphic features are relicts of a former hydrologic regime. This study shows how two kinds of hydrologic models can be used to estimate the quantities of ground water entering a site, as well as compute long-term (40 years) records of water table fluctuations. A water budget was computed for a Carolina Bay wetland that had been drained for agriculture but was being restored to a wetland. Precipitation, potential evapotranspiration, surface outflow, and water stored in the soil were evaluated for a 13-min period to determine the amount of ground water entering the bay. A water table simulation model (DRAINMOD) was used at an additional site in NC to compute 40-year records of hourly water table fluctuations along a soil toposequence. The data were then related to percentages of redox depletions having chromas of 2 or less. The water budget showed that ground water comprised 35% of the total water input into the bay, indicating the site was functioning as a discharge area. Water table hydrographs were used to confirm the ground water inflow estimates as well as the estimate of potential evapotranspiration. The 40-year record of water table data obtained from DRAINMOD was summarized as the average number of times the soils at a given depth was saturated for 21 continuous days or longer. Historic rainfall data were selected from an area having the same rainfall distribution as found at the experimental site. The relationship between number of saturation events and percentage of redoximorphic features showed that some features were forming in soil horizons that saturated only four times within a 10-year period. These were not considered to be relict features because they formed during infrequent saturation events.}, number={3-4}, journal={GEODERMA}, author={Vepraskas, MJ and Huffman, RL and Kreiser, GS}, year={2006}, month={Apr}, pages={287–298} }
 @article{mckay_driese_smith_vepraskas_2005, title={Hydrogeology and pedology of saprolite formed from sedimentary rock, eastern Tennessee, USA}, volume={126}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2004.11.017}, abstractNote={Groundwater flow in sedimentary rock saprolite, and in soils derived from this material, is strongly influenced by sedimentary layering and fractures inherited from the parent bedrock. The main objectives of this study were to determine whether parent bedrock lithology and infilling of fractures and other macropores with pedogenically derived clays and Fe/Mn oxides also play major roles in controlling hydraulic conductivity and groundwater flow. The study was carried out by measuring profiles of saturated and unsaturated hydraulic conductivity, Ksat and K(ψ), and comparing them to soil and saprolite pedology and lithology in a 3.4 m deep pit excavated in interbedded limestone and shale saprolite. In the depth interval of 50 to 100 cm, there was an abrupt decline in Ksat and K(0) by a factor of up to 250. This corresponds to the occurrence of a zone where almost all of the fractures and other macropores are occluded with pedogenic clays and Fe/Mn oxides. Below a depth of 100 cm, both degree of pore infilling and hydraulic conductivity tend to vary, with a spatial regularity that is similar to the thickness of sedimentary layering in the saprolite. However, variations in hydraulic conductivity do not always correspond to changes in lithology, suggesting that hydraulic conductivity is a result of the complex interaction of several factors, including parent bedrock lithology and the degree of infilling of the macropores. Similarities between hydrogeologic conditions at this site and at research sites in weathered sedimentary shale/siltstone and carbonate rock settings at the Oak Ridge Reservation in Tennessee and in weathered crystalline rock in North Carolina indicate that macropore infilling plays an important role in controlling hydraulic conductivity and groundwater flow for a variety of different types of parent bedrock.}, number={1-2}, journal={GEODERMA}, author={McKay, LD and Driese, SG and Smith, KH and Vepraskas, MJ}, year={2005}, month={May}, pages={27–45} }
 @article{vepraskas_2005, title={Predicting contaminant transport along quartz veins above the water table in a mica-schist saprolite}, volume={126}, ISSN={["0016-7061"]}, DOI={10.1016/j.geoderma.2004.11.006}, abstractNote={Saprolite, thoroughly weathered bedrock, is a porous material that can be used treat wastewater. The inherited veins and fractures in saprolite have been suspected of being capable of transmitting the wastes to ground water. This study evaluated the time of travel of a Br− solute through a large quartz vein in a mica schist saprolite. Four 150 by 150 cm drainfields were constructed over a saprolite that contained a single quartz vein that was 45 cm wide and continuous across the site. Following saturation of the saprolite, a Br− tracer and blue-colored dye were applied for a period sufficient for the tracer to leach 30 or 40 cm. Saturated hydraulic conductivity was determined for each drainfield by measuring water intake and also by using the compact constant-head permeameter. The drainfields were then excavated to 90 cm, the dye pattern mapped and soil samples collected for Br− analysis. Dye patterns below the drainfields indicated that virtually no preferential flow along the vein occurred. Depth of dye penetration within the matrix and vein appeared similar. Deeper penetration did occur along root channels, which extended to 80 cm. There was no significant difference (P=0.10) in depth of Br− penetration in saprolite with and without quartz veins. A simple time of travel model predicted maximum depth of solute movement accurately when no preferential flow occurred. These results showed that large quartz veins that contain clay or Fe–Mn oxides between the quartz gravels will conduct water at a rate that is similar to that found for the saprolite matrix. Such veins pose no apparent hazard to wastewater disposal.}, number={1-2}, journal={GEODERMA}, author={Vepraskas, MJ}, year={2005}, month={May}, pages={47–57} }
 @article{caldwell_adams_niewoehner_vepraskas_gregory_2005, title={Sampling device to extract intact cores in saturated organic soils}, volume={69}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2005.0150}, abstractNote={Physical property data on organic soils are lacking due to difficulty in collecting undisturbed samples from these frequently saturated and weakly consolidated soils. A sampling device was constructed to extract undisturbed cores from saturated organic soils in a forested setting. The sampler consists of a 100‐cm‐long, 7.6‐cm‐diam. schedule 40 PVC pipe that was fitted with female threaded adapters on either end. A cutting head was constructed to cut through the fibric root mat and other woody debris in the profile by gluing a 7.6‐cm‐diam. hole‐saw to a male threaded adaptor that was attached to the PVC pipe. The sampler was rotated by hand into the organic soil with gentle downward pressure. When the desired depth was reached, the remaining air space in the PVC pipe was filled with water and a threaded cap was used to seal the top of the sampler. A 1.3‐cm‐diam. galvanized pipe was inserted next to the sampler to add water to the bottom of the core, relieving the suction created as the core was pulled from the soil. The sampler and vent pipe were pulled from the soil either by hand or with a tripod–winch arrangement. Before the cutting head was raised above the water table, it was removed and replaced with another threaded PVC cap. The 100‐cm‐long pipe containing the soil core was then cut into 7.6‐cm‐long sections using a wheel‐type PVC pipe cutter. Saturated hydraulic conductivity and soil water characteristics were then measured in the laboratory using the resulting 7.6‐cm‐long samples encased in the PVC cylinders.}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Caldwell, PV and Adams, AA and Niewoehner, CP and Vepraskas, MJ and Gregory, JD}, year={2005}, pages={2071–2075} }
 @article{vepraskas_he_lindbo_skaggs_2004, title={Calibrating hydric soil field indicators to long-term wetland hydrology}, volume={68}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2004.1461}, abstractNote={Jurisdictional wetlands are required to be saturated to the surface for 5% or more of the growing season in 5 out of 10 yr, but practical field methods for confirming this are lacking. This study determined whether hydric soil field indicators were related to wetland hydrology requirements. Water table levels were monitored daily for 2.5 yr in a toposequence of nine soil plots that included well to poorly drained members (Oxyaquic Paleudults and Typic Albaqualfs). Monitoring data were used to calibrate a hydrologic model that simulated water table levels from inputs of hourly rainfall data. Forty years of rainfall data were then used with the model to compute long‐term daily water‐table levels in each plot. These data were summarized as “saturation events”, which are the frequency that water tables were at or above preselected depths for at least 21 d. Twenty‐one days was the average period needed for Fe reduction to begin in these saturated soils. This condition must occur for hydric soil field indicators to form. Regression equations were developed to relate saturation events to percentages of redoximorphic features. The r2 values for relationships between percentages of redoximorphic features and saturation events were >0.80 for depths of 15 cm, and >0.90 for depths between 30 and 90 cm. Results showed that the depleted matrix field indicator, in which redox depletions occupy >60% of the horizon, occurred in soils that were saturated for 21 d or longer at least 9 yr out of 10. This indicated the depleted matrix indicator occurred in soils that were saturated nearly twice as long, and more frequently, than the minimum requirements needed to meet wetland hydrology requirements.}, number={4}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Vepraskas, MJ and He, X and Lindbo, DL and Skaggs, RW}, year={2004}, pages={1461–1469} }
 @article{he_vepraskas_lindbo_skaggs_2003, title={A method to predict soil saturation frequency and duration from soil color}, volume={67}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2003.0961}, abstractNote={Saturation frequency and duration must be estimated to determine if a site is a jurisdictional wetland, and such data also aid in assessing sites for on-site waste disposal. This study developed a method to estimate saturation frequency and duration by calibrating redoximorphic features to a 40-yr record of water table simulations in a catena of Atlantic Coastal Plain soils in North Carolina. Thirteen plots were established along a toposequence with moderately well-drained (Aquic Paleudults) and very poorly drained soils (Umbric Paleaquults) as end members. A hydrologic model (DRAINMOD) was calibrated for each plot. Redox potential measurements showed that an average of 21 consecutive days of continuous saturation was sufficient for Fe reduction to occur in the soils. Historic rainfall data were used in the DRAINMOD model to estimate the number of times each plot was saturated for 21 consecutive days or longer in each year of a 40-yr period. Redoximorphic features were significantly correlated with average number of saturation events computed to have occurred at depths of 45, 60, 75, and 90 cm across all soils. Relationships were linear and varied by depth when all soils were analyzed as a single population. The r2 values for relationships between redox depletions and saturation events were >0.85 for saturation occurring during the growing season, and were >0.75 for saturation events occurring at any time during the year. These relationships allow prediction of the likelihood that a soil will saturate for ≥21 d by simply estimating the percentage of redoximorphic features at a given depth.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={He, X and Vepraskas, MJ and Lindbo, DL and Skaggs, RW}, year={2003}, pages={961–969} }
 @book{stoops_vepraskas_2003, title={Guidelines for analysis and description of soil and regolith thin sections}, DOI={10.2136/2003.guidelinesforanalysis}, abstractNote={For communication on observations it is very important that a clear, unambiguous terminology is used. This is especially true if one wants to compare observations made by different authors, and certainly when the construction of data bases is considered. Having this in mind, the international group that authored the “Handbook of Soil Thin Section Description” (Bullock et al., 1985), proposed a series of precisely defined concepts with associated terms, as was done before also by Brewer (1964). The advantage of a uniform terminology can easily be lost when the English terms get various translations in another language, e.g. by different authors. In order to overcome this problem G. Stoops published in1986, with the help of colleagues of different countries, a multilingual translation of the terminology of Bullock et al. (1985). For alteration patterns, a translation was proposed by Stoops et al. (1979).}, publisher={Madison, Wis: Soil Science Society of America}, author={Stoops, Georges and Vepraskas, M.J.}, year={2003} }
 @article{he_vepraskas_skaggs_lindbo_2002, title={Adapting a drainage model to simulate water table levels in coastal plain soils}, volume={66}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2002.1722}, abstractNote={Seasonal saturation in soils is expensive and time consuming to document, but the information is needed for land use assessments. Hydrologic models can be used to assess saturation occurrence quickly if the models are calibrated for individual sites. This study determined whether a drainage model (DRAINMOD) could predict water table levels in soils with and without a perimeter ditch. Water table levels were monitored for up to 3 yr at two toposequences that contained a total of 21 soil plots (3 m by 3 m). Soils included Typic Paleudults, Aquic Paleudults, and Umbric Paleaquults. Each plot was instrumented with a recording well to monitor daily water table levels. DRAINMOD was calibrated for each soil plot using measurements of in situ saturated hydraulic conductivity, soil water characteristic, depth to impermeable layer, depth of rooting, and rainfall. A plot's water table fluctuation was simulated by a system of virtual drains whose distance and depth were adjusted to produce simulated water table fluctuations in line with those actually measured. Further calibration adjusted drainable porosity in the upper 20 cm of the soil, depressional storage, evapotranspiration rate, and depth to impermeable layer. Adjustments were made by iteration to minimize the absolute average deviation between simulated and measured water table levels. Calibration had to be done by plot. Average absolute deviations were generally <20 cm for periods ranging from 1 to 3 yr. The results showed that DRAINMOD could be adapted to simulate water table levels in landscapes that do not contain a network of parallel drains.}, number={5}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={He, X and Vepraskas, MJ and Skaggs, RW and Lindbo, DL}, year={2002}, pages={1722–1731} }
 @article{lindbo_vepraskas_rhoton_2001, title={A field method for determing percentage of coated sand grains}, volume={65}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2001.653949x}, abstractNote={Several USDA‐NRCS hydric soil field indicators require estimation of the percentage of organic‐coated sand grains (black grains). For example, to meet the Dark Surface field indicator the soil layer must contain at least 70% coated (black) grains. Field experience has shown that the estimation of the percentage of coated sand grains is often subjective and highly variable from one soil scientist to another. In order to overcome this variability a set of standards was created using a mixture of black and light gray (representing uncoated grains) sand grains. Weighing out each component for the desired ratio and mixing them in a 47‐mm‐diam. petri dish we made a set of three standards consisting of 50, 70, and 90% black grains. To test the effectiveness of these standards, soil scientists estimated the percentage of coated grains from similarly prepared samples first without the use of the standards and then with the use of the standards for comparison. Individuals improved the accuracy of their estimates by 10 to 60% and their hydric soil identification by 16%. The standards are easily prepared, easy to use, and portable.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Lindbo, DL and Vepraskas, MJ and Rhoton, FE}, year={2001}, pages={949–953} }
 @article{grimley_vepraskas_2000, title={Magnetic susceptibility for use in delineating hydric soils}, volume={64}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2000.6462174x}, abstractNote={Field indicators are used to identify hydric soil boundaries and to delineate wetlands. The most common field indicators may not be seen in some soils with thick, dark, mollic epipedons, and do not form in Fe‐poor soils. This study evaluated magnetic susceptibility (MS) meter as a field tool to determine hydric soil boundaries. Five Mollisol‐dominated sites formed in glacial deposits in Illinois were evaluated along with one Ultisol‐dominated site formed in Coastal Plain sediments of North Carolina. Measurements of volumetric MS were made along transects at each site that extended from wetland into upland areas. One created wetland was evaluated. Field indicators were used to identify the hydric soils. Results showed that volumetric MS values were significantly (P < 0.01) lower in hydric soils than in nonhydric soils formed in glacial deposits. Volumetric MS values also decreased slightly with depth. In a created marsh, significant differences in MS were found between hydric and nonhydric soils at 15 to 30 cm but not at shallower depths where topsoil from a wetland had been artificially applied. No significant (P > 0.15) differences in MS were found for Coastal Plain hydric and nonhydric soils where MS values were low (<10 × 10−5 SI). Critical MS values that separated hydric and nonhydric soils varied between 20 × 10−5 and 30 × 10−5 SI for the loessal soils evaluated in Illinois. Such critical values will have to be determined on site using field indicators until specific values can be defined for hydric soils within a given parent material. With a critical MS value in hand, a wetland delineator can make MS measurements along transects perpendicular to the envisioned hydric soil boundary to quickly and quantitatively identify it.}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Grimley, DA and Vepraskas, MJ}, year={2000}, pages={2174–2180} }
 @article{hayes_vepraskas_2000, title={Morphological changes in soils produced when hydrology is altered by ditching}, volume={64}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2000.6451893x}, abstractNote={A soil's hydrology (seasonal saturation occurrence) must be estimated in the field to delineate jurisdictional wetlands and to evaluate soil suitability for on‐site waste disposal. It is difficult to predict soil hydrology on lands that contain ditches, because the areal extent of hydrologic alteration by an individual ditch is generally unknown. This study evaluated whether morphological changes occurred in soils after a drainage ditch had been installed. Four transects of plots were established parallel to a ditch with plots at distances of 7, 30, 60, and 80 m from the ditch. Each transect contained plots in the following soils: Aquic Paleudults, Aeric Paleaquults, and Typic Paleaquults. Soils within 30 m of the ditch had a significantly (0.10 level) greater volume of Fe masses at depths of 40 to 100 cm than soils further from the ditch. Duration of saturation did not vary significantly with distance from the ditch, but within 30 m of the ditch water tables fluctuated more frequently than those in soils further away. Concentrations of Fe(II) in groundwater at a depth of 60 cm were higher at 7 m from the ditch than at 60 m, but redox potentials at a depth of 60 cm were <500 mv for shorter periods of time at 7 m than at greater distances from the ditch. We hypothesized that groundwater flowing into the soils within 30 m of the ditch introduced Fe(II) into the Bt horizons. The Fe(II) oxidized and formed Fe masses as the water table fell. Our results indicate that soil colors can change within 30 yr as a result of ditching. We suggest that the major area of soil influenced by the ditch can be identified by where the Fe masses in the argillic horizons increase as one approaches the ditch.}, number={5}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Hayes, WA and Vepraskas, MJ}, year={2000}, pages={1893–1904} }
 @article{buol_amoozegar_vepraskas_2000, title={Physical, chemical and morphological properties of some Regoliths in North Carolina}, volume={39}, number={3/4}, journal={Southeastern Geology}, author={Buol, S. and Amoozegar, A. and Vepraskas, M. J.}, year={2000}, pages={151} }
 @article{vepraskas_richardson_tandarich_teets_1999, title={Dynamics of hydric soil formation across the edge of a created deep marsh}, volume={19}, ISSN={["1943-6246"]}, DOI={10.1007/bf03161736}, number={1}, journal={WETLANDS}, author={Vepraskas, MJ and Richardson, JL and Tandarich, JP and Teets, SJ}, year={1999}, month={Mar}, pages={78–89} }
 @book{vepraskas_sprecher_1997, title={Aquic conditions and hydric soils the problem soils : proceedings of a symposium sponsored by Divisions S-10 and S-5 of the Soil Science Society of America and A-2 of the American Society of America [i.e. Agronomy] in Seattle, Washington, 14 November 1994}, DOI={10.2136/sssaspecpub50}, publisher={Madison, Wis: Soil Science Society of America,|c1997}, author={Vepraskas, Michael and Sprecher, S.S.}, year={1997} }
 @article{kretzschmar_robarge_amoozegar_vepraskas_1997, title={Biotite alteration to halloysite and kaolinite in soil-saprolite profiles developed from mica schist and granite gneiss}, volume={75}, ISSN={["0016-7061"]}, DOI={10.1016/S0016-7061(96)00089-4}, abstractNote={The chemical weathering of biotite and associated formation of secondary minerals has important implications for the genesis, mineralogy, chemical properties, and physical properties of soils and saprolites developed from biotite-rich parent rocks. In this study, we used a combination of X-ray diffraction, micromorphological, and scanning electron microscopy techniques to investigate biotite weathering in two soil-saprolite profiles (Typic Kanhapludults) developed from granite gneiss and mica schist in the Piedmont region of North Carolina, USA. In both profiles, sand-sized biotite grains appeared to be transformed directly into kaolinized pseudomorphs of biotite without going through a detectable vermiculite or interstratified biotite-vermiculite intermediate weathering stage. Minerals with biotite-vermiculite mixed layers were only detected in small amounts in the clay- and silt-sized fractions of the saprolite. Weathering sand-sized biotite grains exhibited expanded edges, exfoliation, and cleavage along (001) planes. In the saprolite developed from granite gneiss, kaolin intergrowths within weathering biotite grains were observed. The edges of weathering biotite grains were densely covered with tubular halloysite, suggesting a complex transformation of biotite to halloysite. Halloysite was the dominant clay mineral in the saprolite, but the halloysite content in the clay fractions diminished towards the soil surface.}, number={3-4}, journal={GEODERMA}, author={Kretzschmar, R and Robarge, WP and Amoozegar, A and Vepraskas, MJ}, year={1997}, month={Feb}, pages={155–170} }
 @inproceedings{vepraskas_sprecher_1997, title={Overview of aquic conditions and hydric soils [Chapter 1]}, DOI={10.2136/sssaspecpub50.c1}, abstractNote={The rules of U.S. soil taxonomy and wetland delineation are the two principal systems used in the USA to classify soils that are saturated and chemically reduced. The purpose of this chapter is to describe the major reactions that occur in soils classified by both types of systems, and to compare and contrast the systems themselves. Oxidation-reduction (redox) reactions must occur in saturated soils for the soils to have aquic conditions or for them to be hydric soils. The reactions begin when organic matter is oxidized during bacterial respiration and electrons and protons are produced for the reduction process. Reduction of four elements (O, Mn, Fe, or S) is responsible for the creation of virtually all soil indicators (e.g., redoximorphic features) that show that redox reactions have occurred. In U.S. soil taxonomy, soils that are seasonally saturated and reduced have aquic conditions. The term reduced is defined to mean that Fe(II) must be in solution at some time. Soils with aquic conditions must have redoximorphic features, or one of approximately 10 other types of indicators within 50 cm of the surface. Hydric soils are used to identify jurisdictional wetlands. These are wetlands that may not be filled-in unless a permit is issued by an agency of the U.S. Government. Hydric soils formed under conditions of inundation or saturation that lasted long enough during the growing season to develop anaerobic conditions in the upper part of the soil (within 30 cm of the surface). Major differences between hydric soils and soils with aquic conditions are the depths at which saturation and reduction must occur, the timing of the saturation and reduction, and the principle user groups.}, booktitle={Aquic conditions and hydric soils: The problem soils: Proceedings of a symposium sponsored by Divisions S-10 and S-5 of the Soil Science Society of America and A-2 of the American Society of America [i.e. Agronomy] in Seattle, Washington, 14 November 1994}, publisher={Madison, Wis.: Soil Science Society of America}, author={Vepraskas, Michael and Sprecher, S. W.}, editor={M. J. Vepraskas and Sprecher, S. W.Editors}, year={1997}, pages={1–22} }
 @inproceedings{vepraskas_sprecher_1997, title={Summary [Chapter 9]}, DOI={10.2136/sssaspecpub50.c9}, abstractNote={Aquic conditions and hydric soils are similar in concept in that both require saturation, reduction, and indicators of these conditions. They differ in their requirements for verifying whether saturation and reduction occur in the field. Carbon-based indicators may have to be used to identify saturated and reduced conditions in Entisols that inherited red or gray matrix colors from the parent materials. Characteristics that can be used to identify saturated and reduced Mollisols include redoximorphic features in the mollic epipedon and landscape position. Redoximorphic features were observed in Vertisols. Aquic conditions in Andisols are difficult to identify also because these soils do not form well-expressed redoximorphic features. If the soils are saturated and reduced but contain low amounts of Fe, then features composed of C can be used as a morphological indicator of reduction. Such indicators have been used successfully to identify hydric soils.}, booktitle={Aquic conditions and hydric soils: The problem soils: Proceedings of a symposium sponsored by Divisions S-10 and S-5 of the Soil Science Society of America and A-2 of the American Society of America [i.e. Agronomy] in Seattle, Washington, 14 November 1994}, publisher={Madison, Wis.: Soil Science Society of America}, author={Vepraskas, Michael and Sprecher, S. W.}, editor={M. J. Vepraskas and Sprecher, S. W.Editors}, year={1997}, pages={153–156} }
 @article{vepraskas_guthrie_1992, title={IDENTIFYING SOILS WHERE SUBSOILING CAN INCREASE YIELDS OF TOBACCO, CORN, AND COTTON}, volume={5}, ISSN={["0890-8524"]}, DOI={10.2134/jpa1992.0482}, abstractNote={Subsoiling does not increase yields on all soils that contain tillage pans (dense, compacted soil layers), but the reasons for this are not clear. A previous study with corn (Zea mays L.) showed that roots were able to penetrate tillage pans that were aggregated (contained cracks that roots could grow along), but did not penetrate pans that were nonaggregated (did not contain cracks). This study was conducted to determine if a similar relationship occurs for the roots of cotton (Gossypium hirsutum L.) and tobacco (Nicotiana tabacum L.). Root distribution and yield of corn, cotton, and tobacco were measured for nonsubsoiled and subsoiled locations at 18 field sites over a 7-yr period (...)}, number={4}, journal={JOURNAL OF PRODUCTION AGRICULTURE}, author={VEPRASKAS, MJ and GUTHRIE, DS}, year={1992}, pages={482–488} }
 @book{vepraskas_1992, title={Redoximorphic features for identifying aquic conditions}, number={301}, journal={Redoximorphic features for identifying aquic conditions}, publisher={Raleigh, NC : North Carolina Agricultural Research Service, North Carolina State University}, author={Vepraskas, M. J.}, year={1992}, pages={33} }