@article{amoozegar_heitman_2023, title={Analysis of Water Volume Required to Reach Steady Flow in the Constant Head Well Permeameter Method}, volume={10}, ISSN={["2306-5338"]}, url={https://doi.org/10.3390/hydrology10110214}, DOI={10.3390/hydrology10110214}, abstractNote={The most common method for in situ measurement of saturated hydraulic conductivity (Ksat) of the vadose zone is the constant head well permeameter method. Our general objective is to provide an empirical method for determining volume of water required for measuring Ksat using this procedure. For one-dimensional infiltration, steady state reaches as time (t) → ∞. For three-dimensional water flow from a cylindrical hole under a constant depth of water, however, steady state reaches rather quickly when a saturated bulb forms around the hole. To reach a quasi-steady state for measuring Ksat, we assume an adequate volume of water is needed to form the saturated bulb around the hole and increase the water content outside of the saturated bulb within a bulb-shaped volume of soil, hereafter, referred to as wetted soil volume. We determined the dimensions of the saturated bulb using the Glover model that is used for calculating Ksat. We then used the values to determine the volume of the saturated and wetted bulbs around the hole. The volume of water needed to reach a quasi-steady state depends on the difference between the soil saturated and antecedent water content (Δθ). Based on our analysis, between 2 and 5 L of water is needed to measure Ksat when Δθ varies between 0.1 and 0.4 m3 m−3, respectively.}, number={11}, journal={HYDROLOGY}, author={Amoozegar, Aziz and Heitman, Joshua L.}, year={2023}, month={Nov} }
 @article{gomes_soares_amoozegar_alleoni_2023, title={How Does the Use of Biochar, Phosphate, Calcite, and Biosolids Affect the Kinetics of Cadmium Release in Contaminated Soil?}, volume={234}, ISSN={["1573-2932"]}, DOI={10.1007/s11270-023-06452-z}, number={7}, journal={WATER AIR AND SOIL POLLUTION}, author={Gomes, Frederico Prestes and Soares, Matheus Bortolanza and Amoozegar, Aziz and Alleoni, Luis Reynaldo Ferracciu}, year={2023}, month={Jul} }
 @article{kranz_mclaughlin_amoozegar_heitman_2023, title={Influence of compost amendment rate and level of compaction on the hydraulic functioning of soils}, volume={3}, ISSN={["1752-1688"]}, url={https://doi.org/10.1111/1752-1688.13119}, DOI={10.1111/1752-1688.13119}, abstractNote={Abstract}, journal={JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION}, author={Kranz, Christina N. and McLaughlin, Richard A. and Amoozegar, Aziz and Heitman, Joshua L.}, year={2023}, month={Mar} }
 @article{camacho_faundez-urbina_amoozegar_gannon_heitman_leon_2023, title={Subsurface Lateral Solute Transport in Turfgrass}, volume={13}, ISSN={["2073-4395"]}, url={https://doi.org/10.3390/agronomy13030903}, DOI={10.3390/agronomy13030903}, abstractNote={Turfgrass managers have suspected that runoff-independent movement of herbicides and fertilizers is partially responsible for uneven turfgrass quality in sloped areas. We hypothesized that subsurface lateral solute transport might explain this phenomenon especially in areas with abrupt textural changes between surface and subsurface horizons. A study was conducted to track solute transport using bromide (Br−), a conservative tracer, as a proxy of turfgrass soil inputs. Field data confirmed the subsurface lateral movement of Br− following the soil slope direction, which advanced along the boundary between soil horizons over time. A model based on field data indicated that subsurface lateral movement is a mechanism that can transport fertilizers and herbicides away from the application area after they have been incorporated within the soil, and those solutes could accumulate and resurface downslope. Our results demonstrate that subsurface lateral transport of solutes, commonly ignored in risk assessment, can be an important process for off-target movement of fertilizers and pesticides within soils and turfgrass systems in sloped urban and recreational landscapes.}, number={3}, journal={AGRONOMY-BASEL}, author={Camacho, Manuel E. and Faundez-Urbina, Carlos A. and Amoozegar, Aziz and Gannon, Travis W. and Heitman, Joshua L. and Leon, Ramon G.}, year={2023}, month={Mar} }
 @article{carvalho_howard_amoozegar_crozier_johnson_heitman_2023, title={Water vapor transport through bioenergy grass residues and its effects on soil water evaporation}, volume={10}, ISSN={["1539-1663"]}, url={https://doi.org/10.1002/vzj2.20282}, DOI={10.1002/vzj2.20282}, abstractNote={Abstract}, journal={VADOSE ZONE JOURNAL}, author={Carvalho, Henrique D. R. and Howard, Adam M. and Amoozegar, Aziz and Crozier, Carl R. and Johnson, Amy M. and Heitman, Joshua L.}, year={2023}, month={Oct} }
 @article{saltiel_heitman_amoozegar_2022, title={Comparison of infiltration test methods for soil health assessment}, volume={77}, ISSN={["1941-3300"]}, DOI={10.2489/jSWC.2022.00178}, abstractNote={Infiltration rate (IR) has been commonly used as a metric to evaluate soil quality and health. For the USDA Soil Quality Test Kit, a 15 cm (6 in) diameter cylinder is used to measure IR with 444 cm3 (equivalent to 2.54 cm [1 in]) of water while other standard IR procedures require substantially larger volumes of water. The general objective of this study was to compare different methods for IR measurement. Using three replications, IR measurements were conducted along a 9 m (27 ft) long transect in two different soil types by the double-ring infiltrometer (DRI) using 25 and 50 cm (10 and 20 in, respectively) cylinders, single-ring infiltrometer (SRI) using 25 and 50 cm cylinders, Cornell sprinkle infiltrometer (CSI) using a 24.1 cm (9.5 in) cylinder, the USDA recommended procedure using a 15 cm diameter cylinder (hereafter referred to as USDA-15 method), and a modified USDA method using a 24.1 cm diameter cylinder. Although the USDA-15 method is simple and requires a small amount of water, the procedure does not offer an accurate estimate of the soil infiltration potential due to high variability among replications and significant reduction in IR during early stages of water entry into the soil. The CSI procedure was reproducible, but it is more cumbersome to perform than other methods. The DRI, SRI, and CSI methods required a much greater volume of water than the USDA-15 method but produced results that are more consistent. The most consistent results were obtained by the CSI and DRI methods. The modified USDA method results were similar to the SRI method and were an improvement over the original USDA-15 method. For assessing soil health, additional investigations should be conducted to evaluate a modified version of the USDA procedure using a larger cylinder.}, number={6}, journal={JOURNAL OF SOIL AND WATER CONSERVATION}, author={Saltiel, T. M. and Heitman, Joshua L. and Amoozegar, A.}, year={2022}, pages={623–629} }
 @article{amoozegar_heitman_kranz_2022, title={Comparison of soil particle density determined by a gas pycnometer using helium, nitrogen, and air}, volume={11}, ISSN={["1435-0661"]}, url={https://doi.org/10.1002/saj2.20476}, DOI={10.1002/saj2.20476}, abstractNote={Abstract}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Amoozegar, Aziz and Heitman, Joshua L. and Kranz, Christina N.}, year={2022}, month={Nov} }
 @article{camacho_gannon_ahmed_mulvaney_heitman_amoozegar_leon_2022, title={Evaluation of imazapic and flumioxazin carryover risk for Carinata (Brassica carinata) establishment}, volume={5}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2022.27}, DOI={10.1017/wsc.2022.27}, abstractNote={Abstract}, journal={WEED SCIENCE}, publisher={Cambridge University Press (CUP)}, author={Camacho, Manuel E. and Gannon, Travis W. and Ahmed, Khalied A. and Mulvaney, Michael J. and Heitman, Joshua L. and Amoozegar, Aziz and Leon, Ramon G.}, year={2022}, month={May} }
 @article{gomes_barreto_amoozegar_ferracciu alleoni_2022, title={Immobilization of lead by amendments in a mine-waste impacted soil: Assessing Pb retention with desorption kinetic, sequential extraction and XANES spectroscopy}, volume={807}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2021.150711}, abstractNote={Chemical stabilization is an in-situ remediation that uses amendments to reduce contaminant availability in polluted soils. Rates of phosphate, lime, biochar, and biosolids were evaluated as affecting Pb speciation and mobility in soil samples of a mining area located in Vazante, state of Minas Gerais, Brazil. Chemical and mineralogical characterization, desorption kinetics, sequential extraction, leaching evaluation in columns and speciation using X-ray absorption near edge structure were performed. Pb adsorbed on bentonite and on anglesite were the predominant species in the unamended soil. The treatments with phosphate and lime transformed part of the Pb species to pyromorphite. Conversely, part of Pb species was transformed to Pb adsorbed on citrate in the soil amended with biochar, while PbCl2 was formed in soil samples amended with biosolids. Phosphate and lime increased the Pb extracted in the residual fraction, thus showing that more recalcitrant species, such as pyromorphite, were formed. Biosolids and biochar treatments decreased the Pb in the residual fraction, and the fraction associated to organic matter increased after the addition of biosolids. Phosphate and lime were effective to immobilize Pb and to decrease Pb desorption kinetics, but the organic amendments increased the desorption kinetics of Pb in all rates applied. The soil amended with phosphate decreased the Pb leached in the experiment with leaching columns.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Gomes, Frederico Prestes and Barreto, Matheus Sampaio C. and Amoozegar, Aziz and Ferracciu Alleoni, Luis Reynaldo}, year={2022}, month={Feb} }
 @article{park_kang_oinam_amoozegar_pyo_2022, title={Measurement of skeletal density and porosity of construction materials using a new proposed vacuum pycnometer}, volume={196}, ISSN={["1873-412X"]}, DOI={10.1016/j.measurement.2022.111209}, abstractNote={The porosity of construction materials has a direct impact on some of their properties such as sound absorption, heat transfer, and strength. Several traditional procedures have been developed to measure the porosity, however, their applications can be limited because of the low accuracy and measurement complexity among other drawbacks. This study evaluated an in-house constructed vacuum pycnometer that functions based on the ideal gas law. Its performance for determining skeletal density and porosity of a number of construction materials in the forms of powder and solid was evaluated against a commercial gas pycnometer, Archimedes’ method, CT scanning, and mercury intrusion (MIP) test. Compared with the commercial gas pycnometer using He, the maximum difference was less than 4% for powder materials and less than 6% for solid materials. The test results highlight the potentials of the proposed vacuum pycnometer for measuring the skeletal density and porosity of construction materials.}, journal={MEASUREMENT}, author={Park, Sungwoo and Kang, Min-Chang and Oinam, Yanchen and Amoozegar, Aziz and Pyo, Sukhoon}, year={2022}, month={Jun} }
 @article{bartley_amoozegar_fonteno_jackson_2022, title={Particle Densities of Horticultural Substrates}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16319-21}, abstractNote={The heterogeneity of horticultural substrates makes basic physical characteristics, such as total porosity and particle density, difficult to estimate. Due to the material source, inclusion of occluded pores, and hydrophobicity, particle density values reported from using liquid pyknometry, vary widely. Gas pycnometry was used to determine the particle density of coir, peat, perlite, pine bark, and wood substrates. Further precision was examined by gas species and separation by particle size. The calculated particle densities for each material determined by He, N2, and air were relatively constant and varied little despite the species of gas used. Particle size affected the measured particle density of perlite and pine bark but was minimal with coir, peat, and wood. Reducing the particle size removed more occluded pores and the measured particle density increased. Given the small variability, the use of particle density values obtained by gas pycnometry provides repeatable, precise measurements of substrate material total porosity.}, number={3}, journal={HORTSCIENCE}, author={Bartley, Paul C., III and Amoozegar, Aziz and Fonteno, William C. and Jackson, Brian E.}, year={2022}, month={Mar}, pages={379–383} }
 @article{lewis_amoozegar_mclaughlin_heitman_2021, title={Comparison of Cornell sprinkle infiltrometer and double-ring infiltrometer methods for measuring steady infiltration rate}, volume={9}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20322}, abstractNote={Abstract}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Lewis, John and Amoozegar, Aziz and McLaughlin, Richard A. and Heitman, Joshua L.}, year={2021}, month={Sep} }
 @article{askar_youssef_vadas_hesterberg_amoozegar_chescheir_skaggs_2021, title={DRAINMOD-P: A MODEL FOR SIMULATING PHOSPHORUS DYNAMICS AND TRANSPORT IN DRAINED AGRICULTURAL LANDS: I. MODEL DEVELOPMENT}, volume={64}, ISSN={["2151-0040"]}, DOI={10.13031/trans.14509}, abstractNote={Highlights}, number={6}, journal={TRANSACTIONS OF THE ASABE}, author={Askar, Manal H. and Youssef, Mohamed A. and Vadas, Peter A. and Hesterberg, Dean L. and Amoozegar, Aziz and Chescheir, George M. and Skaggs, R. Wayne}, year={2021}, pages={1835–1847} }
 @article{askar_youssef_hesterberg_king_amoozegar_skaggs_chescheir_ghane_2021, title={DRAINMOD-P: A MODEL FOR SIMULATING PHOSPHORUS DYNAMICS AND TRANSPORT IN DRAINED AGRICULTURAL LANDS: II. MODEL TESTING}, volume={64}, ISSN={["2151-0040"]}, DOI={10.13031/trans.14510}, abstractNote={Highlights}, number={6}, journal={TRANSACTIONS OF THE ASABE}, author={Askar, Manal H. and Youssef, Mohamed A. and Hesterberg, Dean L. and King, Kevin W. and Amoozegar, Aziz and Skaggs, R. Wayne and Chescheir, George M. and Ghane, Ehsan}, year={2021}, pages={1849–1866} }
 @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{camacho_heitman_gannon_amoozegar_leon_2021, title={Seed germination responses to soil hydraulic conductivity and polyethylene glycol (PEG) osmotic solutions}, volume={462}, ISSN={["1573-5036"]}, url={https://doi.org/10.1007/s11104-021-04857-5}, DOI={10.1007/s11104-021-04857-5}, number={1-2}, journal={PLANT AND SOIL}, author={Camacho, Manuel E. and Heitman, Joshua L. and Gannon, Travis W. and Amoozegar, Aziz and Leon, Ramon G.}, year={2021}, month={May}, pages={175–188} }
 @article{askar_youssef_chescheir_negm_king_hesterberg_amoozegar_skaggs_2020, title={DRAINMOD Simulation of macropore flow at subsurface drained agricultural fields: Model modification and field testing}, volume={242}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2020.106401}, abstractNote={Macropores are critical pathways through which water and pollutants can bypass the soil matrix and be rapidly transported to subsurface drains and freshwater bodies. We modified the DRAINMOD model to simulate macropore flow using a simple approach as part of developing the DRAINMOD-P model to simulate phosphorus dynamics in artificially drained agricultural lands. The Hagen-Poiseuille’s law was used to estimate the flow capacity of macropores. When ponding depths on the soil surface are greater than Kirkham’s depth, water is assumed to flow through macropores directly to tile drains without interaction with the soil matrix. In the modified model, macropore size is adjusted based on wet or dry conditions while connectivity is altered by tillage. The model was tested using a 4-year data set from a subsurface drained field in northwest Ohio. The soils at the field are classified as very poorly drained and are prone to desiccation cracking. The modified model predicted the daily and monthly subsurface drainage with average Nash-Sutcliffe efficiency (NSE) values of 0.48 and 0.59, respectively. The cumulative drainage over the 4-year simulation period was under-predicted by 8%. The new macropore component was able to capture about 75% of 60 peak drainage flow events. However, surface runoff was over-predicted for the entire study period. Annual water budgets using measured data (precipitation, subsurface drainage, and surface runoff) and model predictions (evapotranspiration, vertical seepage, and change in storage) were not balanced with an average annual imbalance of 6.4 cm. The lack of closure in the water balance suggests that errors may have occurred in field measurements, particularly, surface runoff. Overall, incorporating macropore flow into DRAINMOD improved predictions of daily drainage peaks and enabled the model to predict subsurface drainage flux contributed by macropore flow, which is critical for expanding DRAINMOD to simulate phosphorus transport in subsurface drained agricultural land.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Askar, Manal H. and Youssef, Mohamed A. and Chescheir, George M. and Negm, Lamyaa M. and King, Kevin W. and Hesterberg, Dean L. and Amoozegar, Aziz and Skaggs, R. Wayne}, year={2020}, month={Dec} }
 @article{amoozegar_2020, title={Examination of models for determining saturated hydraulic conductivity by the constant head well permeameter method}, volume={200}, ISSN={["1879-3444"]}, DOI={10.1016/j.still.2020.104572}, abstractNote={In the constant head well permeameter method the saturated hydraulic conductivity (Ks) of the vadose zone is determined by the equation Q = A × Ks, where Q is the steady state rate of water flow into the soil from a cylindrical hole of known diameter under a constant depth of water, and A is a factor that must be calculated by a model. The Glover model for determining factor A was developed approximately 70 years ago by considering the hydrostatic pressure and gravity in a saturated zone around the hole. This model does not depend on soil texture or structure. Newer models, on the other hand, consider both saturated and unsaturated flow of water, and include both Ks and the capillary factor α (sorptive number) that must be determined independently or be estimated based on soil texture and structure. The main objective here is to compare these models and demonstrate that they yield similar results for coarse-textured soils (relatively large α), but those that consider both saturated and unsaturated flow yield unrealistic results for medium- to fine-textured soils with relatively small α values. The soil water profile around a cylindrical hole under a constant depth of water is initially composed of a bulb-shaped saturation zone (pressure head h > 0), saturation front (h = 0), transmission and wetting zones (h < 0), and wetting front. At steady state, a saturated bulb with a finite volume forms around the hole, and the impact of the unsaturated zone away from the hole on water flow within the saturated bulb diminishes. In addition, the surface area of the saturated bulb is numerically equal to the factor A. Using an empirical approach, the factor A determined by the Glover model and each of the other models for different soils (i.e., different α values) was matched against the surface area of a saturated bulb. Then, the volume of the saturated bulb for each case was determined. Since the factor A determined by the models that consider unsaturated flow is inversely related to α, the volume of the saturated bulb for each model increases unrealistically as the soil texture becomes finer. For soils with α < 0.12 cm−1, the volume of the saturated bulb, and the amount of water needed to reach steady state are unrealistically high making the models that depend on α unsuitable for determining Ks by the constant head well permeameter method.}, journal={SOIL & TILLAGE RESEARCH}, author={Amoozegar, Aziz}, year={2020}, month={Jun} }
 @article{fu_tian_amoozegar_heitman_2019, title={Measuring dynamic changes of soil porosity during compaction}, volume={193}, ISSN={0167-1987}, url={http://dx.doi.org/10.1016/j.still.2019.05.016}, DOI={10.1016/j.still.2019.05.016}, abstractNote={Soil porosity and pore-size distribution changes in response to compaction are important for heat, water, and air flow in soils. In this study, we used the thermo-time domain reflectometry (thermo-TDR) technique to investigate dynamics of in-situ soil porosity and pore-size distribution as affected by number of traffic passes, water content and soil depth. The study was conducted at a field site located near Clayton, NC, USA. A roller was dragged across the length of a 3- by 12-m plot three to five times to repeatedly compact the soil after tillage. Nine thermo-TDR probes, installed at 2.5-, 7.5-, and 12.5-cm depths (representing 0–5, 5–10, and 10–15 cm depth intervals, respectively) at three locations within the plot, were used to determine dynamic changes in soil porosity after each compaction event. Pore-size distribution changes within the top soil layer were determined for a subset of conditions by measuring in-situ infiltration at low tension using a mini disk infiltrometer. Nine core samples were also collected (considered to be a destructive method) near each thermo-TDR probe for measuring total porosity and water content after each compaction. Results showed that the thermo-TDR technique can accurately monitor the change of soil porosity during soil compaction compared to the destructive core method. Variability of replicated soil porosity measurements by the thermo-TDR technique (with a root mean square error (RMSE) of 0.011 m3 m−3 and mean standard error (MSE) of 0.010 m3 m−3) was lower than that of the core method (RMSE = 0.017 m3 m−3, MSE = 0.019 m3 m−3). As expected, total soil porosity decreased with the number of passes; a major portion of compaction (59–89% of the total porosity decrease) occurred during the first pass. The trend of topsoil (0–5 cm) compaction differed from that of subsoil layers (5–10 and 10–15 cm). Changes in porosity were highly sensitive to soil water content. For the sandy-textured soil in this study, soil porosity decreased as water content increased (during compaction period), and the maximum compaction (associated with the lowest porosity) was reached at an initial water content range between 0.08 and 0.10 g g-1. Above this range, the compaction level decreased with increasing water content. In addition, there was a shift in pore-size distribution for the surface layer. More importantly, pore-size distribution continued to change with additional traffic passes even after soil total porosity became stable.}, journal={Soil and Tillage Research}, publisher={Elsevier BV}, author={Fu, Yongwei and Tian, Zhengchao and Amoozegar, Aziz and Heitman, Josh}, year={2019}, month={Oct}, pages={114–121} }
 @article{deiss_franzluebbers_amoozegar_hesterberg_polizzotto_cubbage_2017, title={Soil Carbon Fractions from an Alluvial Soil Texture Gradient in North Carolina}, volume={81}, ISSN={0361-5995}, url={http://dx.doi.org/10.2136/sssaj2016.09.0304}, DOI={10.2136/sssaj2016.09.0304}, abstractNote={
Core Ideas
Total, mineral‐associated, and mineralizable C fractions varied along a soil texture gradient.
Specific surface area and Fe oxyhydroxides were positively associated with clay concentration.
Soil C fractions were positively associated with surface area and Fe oxides.
Aluminum oxide was not related to clay concentration or specific surface area.
Mineralizable C had the most complex relationship with clay concentration.
Soil texture is known to affect soil organic C (SOC) concentration and microbial activity, but these relationships are not always straightforward. We characterized total, mineral‐associated, and mineralizable C fractions along a gradient of soil texture within a flood plain field in the Coastal Plain region of North Carolina. Soil was collected from 0‐ to 5‐, 5‐ to 15‐, and 15‐ to 30‐cm depth intervals at 204 locations within a 7‐ha area. Samples were analyzed for soil particle size distribution, specific surface area (SSA), oxalate‐extractable Al and Fe to estimate short‐range‐ordered (i.e., poorly crystalline) oxyhydroxides, and soil C fractions. Overall, relationships among soil C fractions, textural classes, and depths were complex. Both SOC (0.4–13.9 g kg–1 soil) and mineral‐associated organic C (0–12 g kg–1 soil) increased as soil clay concentration increased (73–430 g kg–1 soil), but having two distinct slopes in each relationship with an inflection point of ∼150 g clay kg–1 soil at 0 to 5 and 5 to 15 cm and an inflection point of ∼250 g clay kg–1 soil at 15 to 30 cm. As clay concentration increased, SSA (12–76 m2 g–1 soil) and oxalate‐extractable Fe (0.45–5.9 g kg–1 soil) also increased. A weaker relationship was observed between oxalate‐extractable Al (0.38–1.5 g kg–1 soil) and either SSA or mineral‐associated organic C. Mineralizable C increased with increasing clay concentration up until 143 ± 3, 152 ± 5, and 161 ± 11 g kg–1 (0–5, 5–15, and 15–30 cm, respectively), but decreased (0–5 and 5–15 cm) or stayed constant (15–30 cm) at higher clay concentrations. On the basis of untested observations, we surmise that binding of C to oxalate‐extractable Fe contributed to the accumulation of SOC and suppression of mineralizable C as the clay concentration increased. These results suggest that complex soil texture–physicochemical interactions underlie the inherent fertility of floodplain soils.}, number={5}, journal={Soil Science Society of America Journal}, publisher={Wiley}, author={Deiss, Leonardo and Franzluebbers, Alan J. and Amoozegar, Aziz and Hesterberg, Dean and Polizzotto, Matthew and Cubbage, Frederick W.}, year={2017}, month={Sep}, pages={1096–1106} }
 @article{gillispie_austin_rivera_bolich_duckworth_bradley_amoozegar_hesterberg_polizzotto_2016, title={Soil Weathering as an Engine for Manganese Contamination of Well Water}, volume={50}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84988464669&partnerID=MN8TOARS}, DOI={10.1021/acs.est.6b01686}, abstractNote={Manganese (Mn) contamination of well water is recognized as an environmental health concern. In the southeastern Piedmont region of the United States, well water Mn concentrations can be >2 orders of magnitude above health limits, but the specific sources and causes of elevated Mn in groundwater are generally unknown. Here, using field, laboratory, spectroscopic, and geospatial analyses, we propose that natural pedogenetic and hydrogeochemical processes couple to export Mn from the near-surface to fractured-bedrock aquifers within the Piedmont. Dissolved Mn concentrations are greatest just below the water table and decrease with depth. Solid-phase concentration, chemical extraction, and X-ray absorption spectroscopy data show that secondary Mn oxides accumulate near the water table within the chemically weathering saprolite, whereas less-reactive, primary Mn-bearing minerals dominate Mn speciation within the physically weathered transition zone and bedrock. Mass-balance calculations indicate soil weathering has depleted over 40% of the original solid-phase Mn from the near-surface, and hydrologic gradients provide a driving force for downward delivery of Mn. Overall, we estimate that >1 million people in the southeastern Piedmont consume well water containing Mn at concentrations exceeding recommended standards, and collectively, these results suggest that integrated soil-bedrock-system analyses are needed to predict and manage Mn in drinking-water wells.}, number={18}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Gillispie, Elizabeth C. and Austin, Robert E. and Rivera, Nelson A. and Bolich, Rick and Duckworth, Owen W. and Bradley, Phil and Amoozegar, Aziz and Hesterberg, Dean and Polizzotto, Matthew L.}, year={2016}, month={Sep}, pages={9963–9971} }
 @article{kang_mclaughlin_amoozegar_heitman_duckworth_2015, title={Transport of dissolved polyacrylamide through a clay loam soil}, volume={243}, ISSN={["1872-6259"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84920432092&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2014.12.022}, abstractNote={Polyacrylamide (PAM) is becoming a widely used soil conditioning and erosion control agent, and a better understanding of its transport is required to improve its use. In this study vertical PAM transport through a clay loam soil was investigated using thin soil columns (7.62-cm diameter × 2-cm thick) under saturated condition. The columns received a water-soluble, anionic PAM solution (16 Mg mol− 1 with 50 mol% charge density) under pulse and step (continuous) inputs using a constant-head method. The pulse input was 500 mg L− 1 PAM solution applied for 0.6 pore volume (PV), after which the input was switched to deionized (DI) water for 25 PVs. The step input was 25 mg L− 1 PAM solution applied continuously for 129 PVs. Saturated hydraulic conductivity (Ksat) was measured prior to PAM application and was monitored during PAM and DI water leaching. Leachate samples were collected frequently with time from each column and analyzed for the dissolved PAM concentration. The PAM applications reduced Ksat to 1% of the initial Ksat (4 cm h− 1) under the pulse input and to 0.3% of the initial Ksat under the step input. Transport of PAM was best-fitted with a two-region (dual-porosity) model. The fitted retardation factor (R) was more than two-fold greater for the step input (R = 2695) than for the pulse input (R = 1242). The results from transport modeling and pore size distribution analysis suggested that viscous PAM solution contributes to a mechanical entrapment of the PAM molecules, clogging most water-conducting pores smaller than 225–274 μm in diameter. Under saturated condition, either the pulse or step input of dissolved PAM could reduce seepage with limited mobility in the soil profile.}, journal={GEODERMA}, author={Kang, Jihoon and McLaughlin, Richard A. and Amoozegar, Aziz and Heitman, Joshua L. and Duckworth, Owen W.}, year={2015}, month={Apr}, pages={108–114} }
 @article{kang_amoozegar_heitman_mclaughlin_2014, title={Granular and Dissolved Polyacrylamide Effects on Erosion and Runoff under Simulated Rainfall}, volume={43}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2014.01.0022}, abstractNote={Polyacrylamide (PAM) has been demonstrated to reduce erosion under many conditions, but less is known about the effects of its application method on erosion and concentrations in the runoff water. A rainfall simulation study was conducted to evaluate the performance of an excelsior erosion control blanket (cover) and two PAM application methods. The treatments were (i) no cover + no PAM (control), (ii) cover + no PAM, (iii) cover + granular PAM (GPAM), and (iv) cover + dissolved PAM (DPAM) applied to soil packed in wooden runoff boxes. The GPAM or DPAM (500 mg L) was surface-applied at a rate of 30 kg ha 1 d before rainfall simulation. Rainfall was applied at 83 mm h for 50 min and then repeated for another 20 min after a 30-min rest period. Runoff samples were analyzed for volume, turbidity in nephelometric turbidity units (NTU), total suspended solids (TSS), sediment particle size distribution, and PAM concentration. The cover alone reduced turbidity and TSS in runoff by >60% compared with the control (2315 NTU, 2777 mg TSS L). The PAM further reduced turbidity and TSS by >30% regardless of the application method. The median particle diameter of eroded sediments for PAM treatments was seven to nine times that of the control (12.4 μm). Loss of applied PAM in the runoff water (not sediment) was 19% for the GPAM treatment but only 2% for the DPAM treatment. Both GPAM and DPAM were effective at improving groundcover performance, but DPAM resulted in much less PAM loss.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Kang, Jihoon and Amoozegar, Aziz and Heitman, Joshua L. and McLaughlin, Richard A.}, year={2014}, pages={1972–1979} }
 @article{deol_heitman_amoozegar_ren_horton_2014, title={Inception and Magnitude of Subsurface Evaporation for a Bare Soil with Natural Surface Boundary Conditions}, volume={78}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2013.12.0520}, abstractNote={A dry surface layer (DSL) forms when wet soil is exposed to the sun; development of a DSL coincides with a shift between surface and subsurface evaporation. There remains debate as to when this shift from surface to subsurface evaporation occurs relative to the timing of the shift between potential and falling‐rate evaporation. We performed a field experiment to investigate the onset of subsurface evaporation, development of the DSL, and the extent of the evaporation zone. Our objective was to determine the timing of the onset of subsurface evaporation with respect to decline in evaporation rates. We estimated total (surface plus subsurface) and subsurface soil evaporation rates using microlysimeter (water mass balance) and sensible heat balance (SHB) approaches, respectively, for a bare loamy sand soil under natural wetting and drying cycles. Results showed that the onset of subsurface evaporation coincided with the beginning of falling‐rate evaporation. The evaporation zone extended into the subsurface when evaporation rates fell below the potential rate but were still as high as 50% of potential evaporation. Over a 5‐d drying event, estimated evaporation zones were as deep as 4 to 9 mm, and the estimated DSL had a maximum depth of approximately 6 mm. A low soil water content‐dependent albedo was observed when evaporation occurred at potential rates, but albedo increased as evaporation rates declined. Data from the intensive observation period suggest that this increase in albedo corresponded to formation of a DSL and onset of subsurface evaporation. Overall, surface drying and formation of a DSL appeared to be a dominant process for this coarse‐texture soil exposed to ambient boundary conditions, even as evaporation rates remained relatively high (0.3 mm h−1).}, number={5}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Deol, Pukhraj K. and Heitman, Joshua L. and Amoozegar, Aziz and Ren, Tusheng and Horton, Robert}, year={2014}, pages={1544–1551} }
 @article{stall_amoozegar_lindbo_graves_rashash_2014, title={Transport of E. coli in a sandy soil as impacted by depth to water table}, volume={76}, number={6}, journal={Journal of Environmental Health}, author={Stall, C. and Amoozegar, A. and Lindbo, D. and Graves, A. and Rashash, D.}, year={2014}, pages={92–100} }
 @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{kang_sowers_duckworth_amoozegar_heitman_mclaughlin_2013, title={Turbidimetric Determination of Anionic Polyacrylamide in Low Carbon Soil Extracts}, volume={42}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84887582502&partnerID=MN8TOARS}, DOI={10.2134/jeq2013.07.0279}, abstractNote={Concerns over runoff water quality from agricultural lands and construction sites have led to the development of improved erosion control practices, including application of polyacrylamide (PAM). We developed a quick and reliable method for quantifying PAM in soil extracts at low carbon content by using a turbidimetric reagent, Hyamine 1622. Three high-molecular weight anionic PAMs differing in charge density (7, 20, and 50 mol%) and five water matrices, deionized (DI) water and extracts from four different soils, were used to construct PAM calibration curves by reacting PAM solutions with hyamine and measuring turbidity development from the PAM-hyamine complex. The PAM calibration curve with DI water showed a strong linear relationship ( = 0.99), and the sensitivity (slope) of calibration curves increased with increasing PAM charge density with a detection limit of 0.4 to 0.9 mg L. Identical tests with soil extracts showed the sensitivity of the hyamine method was dependent on the properties of the soil extract, primarily organic carbon concentration. Although the method was effective in mineral soils, the highest charge density PAM yielded a more reliable linear relationship ( > 0.97) and lowest detection limit (0.3 to 1.2 mg L), compared with those of the lower charge density PAMs (0.7 to 23 mg L). Our results suggest that the hyamine test could be an efficient method for quantifying PAM in environmental soil water samples as long as the organic carbon in the sample is low, such as in subsurface soil material often exposed at construction sites.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Kang, Jihoon and Sowers, Tyler D. and Duckworth, Owen W. and Amoozegar, Aziz and Heitman, Joshua L. and McLaughlin, Richard A.}, year={2013}, pages={1902–1907} }
 @article{deol_heitman_amoozegar_ren_horton_2012, title={Quantifying nonisothermal subsurface soil water evaporation}, volume={48}, ISSN={0043-1397}, url={http://dx.doi.org/10.1029/2012WR012516}, DOI={10.1029/2012wr012516}, abstractNote={Accurate quantification of energy and mass transfer during soil water evaporation is critical for improving understanding of the hydrologic cycle and for many environmental, agricultural, and engineering applications. Drying of soil under radiation boundary conditions results in formation of a dry surface layer (DSL), which is accompanied by a shift in the position of the latent heat sink from the surface to the subsurface. Detailed investigation of evaporative dynamics within this active near‐surface zone has mostly been limited to modeling, with few measurements available to test models. Soil column studies were conducted to quantify nonisothermal subsurface evaporation profiles using a sensible heat balance (SHB) approach. Eleven‐needle heat pulse probes were used to measure soil temperature and thermal property distributions at the millimeter scale in the near‐surface soil. Depth‐integrated SHB evaporation rates were compared with mass balance evaporation estimates under controlled laboratory conditions. The results show that the SHB method effectively measured total subsurface evaporation rates with only 0.01–0.03 mm h−1difference from mass balance estimates. The SHB approach also quantified millimeter‐scale nonisothermal subsurface evaporation profiles over a drying event, which has not been previously possible. Thickness of the DSL was also examined using measured soil thermal conductivity distributions near the drying surface. Estimates of the DSL thickness were consistent with observed evaporation profile distributions from SHB. Estimated thickness of the DSL was further used to compute diffusive vapor flux. The diffusive vapor flux also closely matched both mass balance evaporation rates and subsurface evaporation rates estimated from SHB.}, number={11}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={Deol, Pukhraj and Heitman, Josh and Amoozegar, Aziz and Ren, Tusheng and Horton, Robert}, year={2012}, month={Nov} }
 @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{kang_amoozegar_hesterberg_osmond_2011, title={Phosphorus leaching in a sandy soil as affected by organic and inorganic fertilizer sources}, volume={161}, ISSN={["0016-7061"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79951581004&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2010.12.019}, abstractNote={Long-term application of phosphorus (P) to soils as fertilizer or manure can increase the potential for P loss to ground and surface waters. Vertical P transport was investigated in a sandy soil material receiving seven different P fertilizer sources: poultry compost, poultry litter, triple superphosphate [Ca(H2PO4)2·H2O], dairy lagoon liquid, swine lagoon liquid, swine lagoon sludge, and dissolved potassium dihydrogen phosphate (KH2PO4). The P sources were surface-applied to soil columns (6.35-cm diameter, 10-cm long) at two rates equivalent to 75 and 150 kg total P ha−1, and columns were intermittently leached with deionized (DI) water. Column effluents were collected for up to 23 pore volumes and analyzed for dissolved reactive phosphorus (DRP) and dissolved organic carbon (DOC). In addition, a P retardation factor was determined for the soil from a P adsorption isotherm. Transport of P through soil columns receiving liquid P sources was simulated by a one-dimensional equilibrium convective–dispersive equation (CDE) based on water-extractable P (WEP) concentrations. Cumulative amounts of DRP leached were linearly related to the amounts of WEP in P source materials (r2 = 0.87***). The recovery of DRP in the column effluents relative to WEP in the applied materials was 126 ± 15% (mean ± standard error) for organic P sources and 66 ± 2% for inorganic P sources. The use of WEP in the CDE model underpredicted P transport in the columns amended with lagoon liquids compared with dissolved KH2PO4. Results indicated that leaching losses of P from land-applied manures exceed the amounts of WEP in source materials because of organic P mineralization and competitive sorption of DOC.}, number={3-4}, journal={GEODERMA}, author={Kang, Jihoon and Amoozegar, Aziz and Hesterberg, Dean and Osmond, Deanna L.}, year={2011}, month={Mar}, pages={194–201} }
 @article{stanford_amoozegar_weinberg_2010, title={The impact of co-contaminants and septic system effluent quality on the transport of estrogens and nonylphenols through soil}, volume={44}, ISSN={["0043-1354"]}, DOI={10.1016/j.watres.2009.11.011}, abstractNote={The impact that varying qualities of wastewater may have on the movement of steroid estrogens through soils into groundwater is little understood. In this study, the steroid estrogens 17beta-estradiol (E2) and estrone (E1) were followed through batch and column studies to examine the impact that organic wastewater constituents from on-site wastewater treatment systems (i.e., septic systems or decentralized systems) may have on influencing the rate of transport of estrogens through soils. Total organic carbon (TOC) content (as a surrogate indicator of overall wastewater quality) and the presence of nonyl-phenol polyethoxylate surfactants (NPEO) at concentrations well below the critical micelle concentration were independently shown to be indicative of earlier breakthrough and less partitioning to soil in batch and column experiments. Both NPEO and wastewater with increasing TOC concentrations led to shifts in the equilibrium of E1 and E2 towards the aqueous phase and caused the analytes to have an earlier breakthrough than in control experiments. The presence of nonylphenols, on the other hand, did not appreciably impact partitioning of E1 or E2. Biodegradation of the steroids in soil was also lower in the presence of septic tank effluents than in an organic-free control water. Furthermore, the data indicate that the rate of movement of E1 and E2 present in septic tank effluent through soils and into groundwater can be decreased by removing the NPEOs and TOC through wastewater treatment prior to sub-surface disposal. This study offers some insights into mechanisms which impact degradation, transformation, and retardation, and shows that TOC and NPEO surfactants play a role in estrogen transport.}, number={5}, journal={WATER RESEARCH}, author={Stanford, Benjamin D. and Amoozegar, Aziz and Weinberg, Howard S.}, year={2010}, month={Mar}, pages={1598–1606} }
 @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{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, M. J. and Niewoehner, C. P.}, year={2008}, pages={890–898} }
 @article{amoozegar_niewoehner_lindbo_2008, title={Water flow from trenches through different soils}, volume={13}, DOI={10.1061/(ASCE)1084-0699(2008)13:8(655)}, abstractNote={It is often assumed that soils are homogeneous when designing septic systems or modeling wastewater flow from their trenches. The main objective of this study was to assess water infiltration and movement from the trenches similar to the ones commonly used for on-site wastewater dispersal by septic systems. Four separate experiments, each using a small drainfield with four parallel trenches, were conducted at three sites with different soils. In two experiments the trenches were in the coarse-textured soil above a clayey Bt horizon. In the other two experiments the trenches were in the Bt horizon. For each experiment, 50 L of a solution containing potassium bromide and brilliant blue FCF (as a tracer dye) were applied once a day to each trench for 14 or 15 days. A sampling pit was dug perpendicular to the trenches after the tracer solution application, and the distribution of the tracer dye and Br− around the trenches on the two walls of the pit were assessed. Tracer solution infiltration from the trenche...}, number={8}, journal={Journal of Hydrologic Engineering}, author={Amoozegar, Aziz and Niewoehner, C. and Lindbo, D.}, year={2008}, pages={655–664} }
 @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} }
 @inbook{amoozegar_wilson_1999, title={Methods for measuring hydraulic conductivity and drainage porosity}, ISBN={0891181415}, DOI={10.2134/agronmonogr38.c38}, abstractNote={This chapter presents a summary of proposed methodologies for determining soil hydraulic properties using simpler measurements and less data. R. E. Green and A.T. Corey compared parameter values for the equation when calculating unsaturated hydraulic conductivity and found that, when a measured conductivity was used as a matching factor, the fit with experimental data was better. Under surface ponded conditions, much water can be conducted through a single or interconnected macropore(s); thereby bypassing the soil matrix and resulting in an overestimation of saturated hydraulic conductivity of the soil matrix during infiltration. Tillage and related management practices cause a temporal variability insoil-water properties and contribute to spatial variability on a local scale. Methods based upon empirical correlations, simplified theoretical relations and observations at restricted locations were presented and followed by those based upon analysis of spatial and temporal distributions associated with infiltration and redistribution.}, booktitle={Agricultural drainage}, publisher={Madison, Wis., : American Society of Agronomy}, author={Amoozegar, Aziz and Wilson, G. W.}, editor={R. W. Skaggs and Schilfgaarde, J. VanEditors}, year={1999}, pages={1149} }
 @inproceedings{weymann_amoozegar_hoover_1998, title={Performance of an on-site wastewater disposal system in a slowly permeable soil}, booktitle={On-site wastewater treatment: Proceedings of the eighth national symposium on individual and small community sewage systems, March 8-10, 1998, Orlando, Florida}, publisher={St. Joseph, Mich.: American Society of Agricultural Engineers}, author={Weymann, D. F. and Amoozegar, A. and Hoover, M. T.}, year={1998}, pages={134–145} }
 @inproceedings{amoozegar_niewoehner_1998, title={Soil hydraulic properties affected by various components of domestic wastewater}, booktitle={On-site wastewater treatment: Proceedings of the eighth national symposium on individual and small community sewage systems, March 8-10, 1998, Orlando, Florida}, publisher={St. Joseph, Mich.: American Society of Agricultural Engineers}, author={Amoozegar, A. and Niewoehner, C. P.}, year={1998}, pages={155–166} }
 @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} }
 @article{li_amoozegar_robarge_buol_1997, title={Water movement and solute transport through saprolite}, volume={61}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj1997.03615995006100060027x}, abstractNote={Abstract}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Li, K and Amoozegar, A and Robarge, WP and Buol, SW}, year={1997}, pages={1738–1745} }
 @article{amoozegar_hoover_1989, title={Movement of water and chemical pollutants from wastewater disposal systems through the soil and saprolite of Piedmont landscapes}, number={249}, journal={Water Resources Research Institute News of the University of North Carolina}, author={Amoozegar, A. and Hoover, M. T.}, year={1989}, pages={153} }