Department: Soil Science ![[clear]](close-x.png "Remove this limiter")
29 matches in the database.
These are records: 1 - 29.
1.
Anderson, Richard Hunter.
Soil Physical And Chemical Property Effects On Toxicity And Bioaccumulation Of As (V), Cd, Pb, And Zn By Herbaceous Plant Receptors.
Degree: PhD, Soil Science, 2008, Ohio State University
► Soil properties can mitigate hazardous effects of environmental contaminants through soil chemical…
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▼ Soil properties can mitigate hazardous effects of environmental contaminants through soil chemical sequestration and should be considered when evaluating ecological risk from terrestrial contamination. The objective of this research was to identify predominant soil chemical/physical properties that modify phytoaccumulation and phytotoxicity of As (V), Cd, Pb, and Zn to the non-hyperaccumulating higher plants; Alfalfa (Medicago sativa L.), Perennial ryegrass (Lolium perenne L.), and Japanese millet (Echinochloa crusgalli L.) and model effects with statistical prediction equations. Bioassays were conducted on five artificially contaminated experimental soils that ranged in selected chemical/physical properties. Soil properties selected for characterization included organic C (OC), pH, cation exchange capacity (CEC), clay content, and amorphous oxides of iron (Fe), aluminum (Al), and manganese (Mn). Phytotoxicity and phytoaccumulation parameters were estimated from dose-response experiments for each contaminant-plant-soil combination. Significant statistical associations were found between each endpoint and a subset of the selected soil properties for all four contaminants. However, significant intercorrelation was observed among soil property measurements which necessitated an alternative to conventional multiple regression commonly used by ecotoxicologists. Ridge regression, a technique that suppresses the effects of multicollinearity and enables prediction, was used to assess the marginal contributions of each mitigating soil property. In general, Ridge regression results suggested that OC, clay content, and soil pH, collectively, or CEC, individually, best described trends in phytoaccumulation and phytotoxicity for the cationic metals. Conversely, Ridge regression results suggested that soil pH and the Fe oxide fraction were usually the most important properties found to mitigate As phytoaccumulation and phytotoxicity. An additional objective was to evaluate differential contaminant sensitivities of the experimental plants that were used in the dose-response experiments as inter-species variability can limit the utility of statistical models used to predict the effects of soil properties on phytotoxicity of terrestrial contaminants. We, therefore, present a novel approach to toxicity estimation (the Plant Contaminant Sensitivity Index) that partitions the effect of differential sensitivities of test organisms from that of soil properties. The proposed normalization procedure is simply illustrated and is intended to be used as a means to integrate toxicity information from different studies with multiple test species.
Advisors/Committee Members: Basta, Nicholas.
Subjects: Environmental science; Soil sciences
Keywords: Phytotoxicity; Phytoaccumulation; Ridge; Soil
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2.
Baker, Barbara J.
Effect of water table management on selected physical properties and carbon fractions of a Hoytville soil in Northwest Ohio.
Degree: PhD, Soil Science, 2002, Ohio State University
► Research was conducted to determine how water table management affects select physical…
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▼ Research was conducted to determine how water table management affects select physical properties and carbon fractions of a Hoytville clay loam soil. The research took place at the Northwest Branch of the Ohio Agricultural Research and Development Center in Wood County, Ohio. Water table management treatments included subsurface drainage and subsurface drainage with subirrigation. Subirrigation was applied during the vegetative, flowering and seed fill stages of crop growth to maintain a constant water table at 0.25 m below the surface and prevent moisture stress in the crops. The cropping system was a corn soybean rotation with fall tillage with a chisel for both crops and spring leveling with a Roterra before planting soybeans. Results show a difference in water stable aggregates (WSA) at a depth of 0.4 – 0.75 meters with the subirrigated treatment having a lower percentage of WSA. The mean weight diameter of aggregates in the subirrigated treatment was smaller than in the subsurface drainage treatment at a depth of 0.3 – 0.75 meters. A shift in the pore size distribution toward smaller pores in the subirrigated treatment further supported “loss of stable soil structure” theory for the subirrigated treatment. Penetration resistance measurements also revealed a change in the structural stability of the soil at a depth of 0.30 – 0.45 meters. No differences were seen between water management treatments in the carbon fractions of the upper 0 – 0.20 meters of the soil. The CENTURY model was tested to determine if it could be used to predict levels of soil organic matter as a result of subirrigation. The model was unable to predict the amount of total SOM in the soil unless the starting value of carbon was lowered well below actual values. Subirrigation of the Hoytville soil led to a loss of stable structure at a depth of approximately 0.40 meters in the soil. The exact reason for the loss of soil structure is unclear but may be related to long periods of saturation resulting from the subirrigation.
Advisors/Committee Members: Fausey, Norman R.
Keywords: Water table management; Subirrigation; Drainage; Carbon; Soil Structure; CENTURY model; Aggregation
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3.
Bardhan, Sougata.
BACTERIAL COMMUNITIES CAPABLE OF ENHANCED EPTC AND ATRAZINE DEGRADATION IN OHIO SILT LOAM AND SILTY CLAY LOAM SOILS.
Degree: PhD, Soil Science, 2010, Ohio State University
► Approximately 7.5 – 8.0 million kg of EPTC (S-ethyldipropylthiocarbamate) and 32 million…
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▼ Approximately 7.5 – 8.0 million kg of EPTC (S-ethyldipropylthiocarbamate) and 32 million kg of atrazine (2-chloro-4-(ethylamine)-6-(isopropylamine)-s-triazine) are used each year for crop production in the United States. Recent reports have raised concern about continued use of these herbicides because of their negative impacts on aquatic life and potential endangerment of animal/human health. Therefore rapid degradation of these herbicides after intended action is important to prevent non-target pollution associated with their presence in the environment. In this study, a culture independent metagenome approach was used to identify bacteria capable of degrading EPTC and atrazine. Two different soils (Wooster silt loam and Luray silty clay loam) were evaluated for development of enhanced degradation by successive application of these herbicides. A polymerase chain reaction (PCR) technique was used to monitor the appearance of the specific genes thcA, thcB, thcC, thcD and thcR for EPTC degradation and atzB, atzD, trzD and trzN for atrazine degradation. Whereas no EPTC or atrazine degrading genes were detected in control soils, presence of these genes in the enhanced soils confirmed the higher degradation potential observed. A PCR-DGGE (Polymerase Chain reaction – Denaturing Gradient Gel Electrophoresis) method was used to amplify and characterize the V-3 (338 to 518) region of the 16s rRNA gene from soil DNA extracted from the enhanced soils to identify the dominant bacteria involved in the degradation of the herbicides. Unique DGGE band profiles obtained for each soil sample were used to calculate the bacterial richness index and Dice similarity index. The values for these indices showed that microbial community abundance and distribution was greatly impacted due to successive exposure of these two herbicides. Selected DGGE bands were excised, cloned and sequenced to identify the dominant bacterial species in the EPTC and atrazine enhanced soils. From the 16S rRNA clone libraries, a total of 64 clones were sequenced. DNA sequence data confirmed the presence of known EPTC and atrazine degrading bacterial species such as Sphingomonas sp., Rhodococcus sp., and Actinobacterium sp. Several uncultured bacterial species, earlier detected in aromatic chemicals contaminated sites, were also identified. Two bacterial species, Kaistobacter sp. and Gemmatomons sp., were identified that have not been reported yet as degraders of these two chemicals. Identification of novel bacterial species capable of degrading these herbicides provides evidence for the vast diversity in microbial communities that still remains to be explored. Knowledge gained about these bacterial degraders will be useful in elucidating novel pesticide degradation pathways and in developing methods for bioremediation to reclaim contaminated soils.
Advisors/Committee Members: Dick, Warren.
Subjects: Agronomy; Environmental science; Microbiology; Soil sciences
Keywords: EPTC, atrazine, enhanced degradation, PCR, DGGE, bacterial community, bioremediation
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4.
Bast, Laura E.
Evaluation of nitrogen recommendations for corn based on soil analysis and remotely sensed data.
Degree: MS, Soil Science, 2009, Ohio State University
► Nitrogen (N) fertilizer is applied to corn (Zea mays L.) annually to…
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▼ Nitrogen (N) fertilizer is applied to corn (Zea mays L.) annually to compensate for losses in grain removal and to the environment. It is important to identify optimum N fertilizer requirements to obtain maximum economic return, while reducing environmental impact. The presidedress soil nitrate test (PSNT) may be used to predict if a grain yield response to additional N fertilizer is likely. The normalized difference vegetation index (NDVI), based on remote sensing measurements derived from canopy reflectance of near-infrared and red light, and existing sensor-based algorithms may aid in improving N fertilizer recommendations. The objectives of this study were to identify optimum sidedress N fertilizer rates obtained using sensor-based algorithms and evaluate the PSNT in corn that received preplant manure applications. The relationships between remotely sensed information, ear-leaf N concentration, and soil NO3-N concentration were also determined.The study was conducted at the Western Research Station of the Ohio Agricultural Research and Development Center (OARDC) near South Charleston, Ohio, in 2007 on Crosby silt loam (a fine mixed, active, mesic Aeric Epiaqualf) and on Kokomo silty clay loam (a fine, mixed superactive, mesic Typic Argiaquoll) in 2008. An additional site was located at the OARDC East Badger Farm near Wooster, Ohio, on Canfield silt loam (a fine-loamy, mixed active, mesic Aquic Fragiudalf). A split-plot, randomized complete block design was used at all three sites. Three manure preplant application rates were used as main plots, and five sidedress N application rates were used as subplots. The 15 treatments were replicated four times. Soil samples for PSNT evaluation and remote sensing measurements were collected between the V6-V8 growth stages. Ear-leaf samples for total N analysis were collected at initial silking (R1 growth stage). The critical value for the PSNT was identified using three types of segmented models. Remote sensing measurements were used in existing algorithms to predict sidedress N recommendations. When compared to empirical evidence, the sensor-based algorithms under-predicted sidedress N recommendations. The sensor was only able to distinguish NDVI measurements among preplant treatment rates at the 2008 Western Branch OARDC site. Collection of remote sensor measurements needs to be researched further to improve the sensor’s ability to distinguish between preplant treatment rates. The presidedress soil nitrate test critical value for all sites combined was 13-22 µg/g, depending on the model. This indicated that a grain yield response to N fertilizer was unlikely at a soil test NO3-N value > 22 µg/g. There was no relationship between NDVI and PSNT or between NDVI and ear-leaf N concentration. However, at the 2008 Western OARDC site, ear-leaf N increased linearly with soil NO3-N conentration.
Advisors/Committee Members: Eckert, Donald.
Subjects: Agriculture; Agronomy; Soil sciences
Keywords: corn; nitrogen recommendations; NDVI; PSNT; remote sensing
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5.
Beak, Douglas Gerald.
Lead and arsenic speciation and bioaccessibility following sorption on oxide mineral surfaces.
Degree: PhD, Soil Science, 2005, Ohio State University
► The risk posed from incidental ingestion of arsenic-contaminated or lead-contaminated soil may…
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▼ The risk posed from incidental ingestion of arsenic-contaminated or lead-contaminated soil may depend on sorption of arsenate (As(V)) or lead (Pb(II)) to oxide surfaces in soil. Arsenate or lead sorbed to ferrihydrite, corundum, and birnessite model oxide minerals were used to simulate possible effects of ingestion of soil contaminated with As(V) or Pb(II). Arsenate or lead sorbed oxides were placed in a simulated gastrointestinal tract (in vitro) to ascertain the bioaccessibility of As(V) or Pb(II) and changes in As(V) or Pb(II) surface speciation. The speciation of As or Pb was determined using EXAFS and XANES analysis. The As(V) adsorption maximum was found to be 7.04 g kg-1, and 0.47 g kg-1 for ferrihydrite and corundum, respectively. The bioaccessible As(V) for ferrihydrite ranged form 0 to 5 % and for corundum ranged from 0 to 16 %. The surface speciation for ferrihydrite and corundum was determined to be binuclear bidentate. These results for As(V) sorbed to ferrihydrite and corundum suggest that the bioaccessibility of As(V) is related to the As(V) concentration, and the As(V) adsorption maximum. The bioaccessibility of As(V) sorbed to birnessite ranged from 16 to 28 % and the As(V) surface speciation was binuclear bidentate. The results for As (V) sorbed birnessite suggest that birnessite can reduce the bioaccessibility of As(V) in contaminated soil. Sorption of Pb(II) was significant for all the model oxides used. The sorption maximum was found to be 2.13 g kg-1 for corundum, 38.6 g kg-1 for ferrihydrite, and 127 g kg-1 for birnessite. The bioaccessible Pb(II) ranged from 53 to 88 % for ferrihydrite, Pb(II) concentrations greater than 200 mg kg-1 was greater than 85 % for corundum and below 200 mg kg-1 there was no bioaccessible Pb(II). There was no measurable bioaccessible Pb(II) for any concentration of Pb sorbed birnessite. The surface Pb(II) speciation was found to be: 1. Mononuclear bidentate for ferrihydrite, 2. Mononuclear bidentate and an outer-sphere complex for corundum, and 3. Binuclear bidentate, and trinuclear tridentate for birnessite. Ferrihydrite and corundum usefulness in Pb remediation would be limited when risk of incidental ingestion is of major concern.
Advisors/Committee Members: Basta, Nicholas T.
Keywords: Arsenic; Lead; bioaccessibility; bioavailability; Fe oxides; Al Oxides; Mn Oxides; Ferrihydrite; Corundum; Birnessite; As Speciation; Pb Speciation; EXAFS; XANES
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6.
Castro Filho, Celso de.
Effects of liming on characteristics of a Brazilian oxisol at three levels of organic matter as related to erosion.
Degree: PhD, Soil Science, 1988, Ohio State University
► An oxisol from southern Brazil was characterized for parameters related to the…
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▼ An oxisol from southern Brazil was characterized for parameters related to the effects of liming on soil stabili¬ty and erosion. The parameters measured were soil mineralo¬gy, PZSE, pH, soil solution chemistry, moisture retention, pore size distribution, particle and bulk density, aggregate size distribution, effect of ionic strength, organic matter and pH on splash, and effect of lime on runoff, infiltration, saturation time and soil losses. The experimental sites, LC, LM,and CA had increasing carbon con¬tents. Exchangeable acidity was neutralized in field plots to give a pH range of 3.5 to 6.5. Main results were: the LC and LM soils contained more kaolinite than CA soil. CA soil had more gibbsite. The amount of organic carbon had little effect on the PZSE. In LC and LM soils maximum aggregate size occurred when 100% of the exchangeable acidity was neutralized. Al-polymerization and adhesion to soil particles increased aggregate size.Splash decreased with increasing pH and the effect of pH was modified by ionic strength. Both splash and soil loss decreased with increasing pH of the field-limed plots. Splashed soil as a function of pH and organic matter behaved in a manner opposite to the aggregation data, for the same pH. When splash decreased, aggregation increased. Soil splash was also proportional to moisture content regardless of the soil bulk density. Soil loss was reduced when the limed plots were compared to the unlimed plots.
Advisors/Committee Members: Logan, Terry J.
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7.
Diedrick, Keith Anthony.
Field Investigations of Nitrogen Fertility on Corn and Soybeans and Foliar Manganese-Glyphosate Interactions on Glyphosate-Tolerant Soybeans in Ohio.
Degree: PhD, Soil Science, 2010, Ohio State University
► This dissertation is comprised of three separate studies in soil science and…
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▼ This dissertation is comprised of three separate studies in soil science and fertility. The first component concerns the use of swine manure on a leguminous crop. Recent environmental pressure has been placed to limit the practice of applying animal manures to fields planned for soybean [Glycine max (L.) Merr] production because of the perceived hazard of excessive NO3 movement offsite. The objective is to evaluate the impact of manure application to soybean fields on soil NO3-N, N uptake and soybean crop productivity. A field experiment was established in the spring of 2007 and 2008. Liquid swine (Sus scrofa domestica) manure was applied at three different N rates (based upon manure analysis and estimated availability) using two application methods (surface application or injection). Commercial fertilizer treatments (same equivalent rates) were also included as positive controls. Soil samples to 60 cm and tissue samples were collected throughout the growing season. Even though N application did result in higher soil NO3- levels for some treatments, applications rates that were less than or equal to 135 kg ha-1 represented a lower risk of possible NO3-N movement. Nitrogen supplied via manure and commercial fertilizer resulted in larger N uptake than the controls, but grain yield was not improved. This reveals that despite the fact that soybeans can fix their own N, soybeans will absorb soil inorganic-N as a net N sink. The second chapter of the dissertation explores the interactions of foliar-applied manganese and the herbicide glyphosate on glyphosate-resistant weeds. Glyphosate is a metal chelating agent that interacts with cations essential to plant growth, and previous studies have shown interactions with Mn resulting in decreased herbicide efficacy and manganese metabolism issues. This study measured the effects of different formulations of glyphosate and manganese combinations as well as timing of the application. Of six site-years, one instance of manganese application showed a positive grain yield response, regardless of glyphosate rate and timing. One site-year showed a negative yield response from the addition of manganese, suggesting that when manganese is not deficient, the toxic limit is easily reached and may account for yield depression. The final chapter of the dissertation tests the effects of N rate and timing on corn (Zea mays, L.) yield components. As part of a multi-state study using normalized difference vegetative indices in precision placement of N fertilizers, effects of delayed N nutrition by growth stage and rate on the physiology of grain filling could lend greater insight to the logistics of precision placement. Four site-years of data were analyzed in a factorial design comparing five N rates (0, 67, 135, 201, and 269 kg ha-1) at each of the growth stages of preplant, V4, V8, and V12. Results were not consistent over four site-years of data, though the yield data suggest that any N application at V8 and V12 was not able to overcome the permanent yield losses caused by N deficiencies compared to an unlimited control treatment.
Advisors/Committee Members: Mullen, Robert.
Subjects: Agricultural chemicals; Agriculture; Agronomy; Soil sciences
Keywords: soil fertility; agronomy; corn; soybeans; manganese; glyphosate; yield components; manure; nitrogen management
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8.
Florence, Darlene Christina.
Growth Performance of Six Plant Species and Removal of Heavy Metal Pollutants (Cu, Cr, Pb and Zn) in a Field-Scale Bi-Phasic Rain Garden.
Degree: MS, Soil Science, 2009, Ohio State University
► A field-scale, bi-phasic rain garden (three replicates) was constructed to evaluate the…
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▼ A field-scale, bi-phasic rain garden (three replicates) was constructed to evaluate the growth of six plant species native to Ohio and the effectiveness of the rain garden to remediate heavy metals (Cu, Cr, Pb and Zn) from simulated stormwater runoff. The first phase, an anaerobic, oxygen-poor zone contained Eupatorium perfoliatum (boneset), Tradescantia ohiensis (spiderwort) and Veronicastrum virginicum (culver’s root). In the second, aerobic, oxygen-rich zone Sorghastrum nutans (Indian grass), Echinacea purpurea (purple coneflower) and Eragrostis spectabilis (purple lovegrass) were grown. The plants, 234 overall, were evaluated over six months in 2008 and four months in 2009 with regards to height, width, number of flowers and general observations. Heavy metal remediation was evaluated over three simulated storm events that were carried out over an 11-day period with each rain event five days apart. During the first two storms, heavy metal pollutants were applied and the effluent water was measured on the eleventh day. On a mass balance basis, there was greater than 99% removal efficiency for Cu, Cr and Pb. In one replication, there was only a 72% removal of Zn, whereas the removal efficiency for the other two replications was greater than 99%. Most of the plants established well. The grasses S. nutans and E. spectabilis established slowest and E. perfoliatum and E. purpurea established the fastest. After the first year, 91% of the total plants survived and re-grew in the second year. V. virginicum had the poorest survival with nearly a quarter of the plants not growing in the second year, the highest of any species. The suitability of this species and E. perfoliatum, with its leaves having been eaten by insects, is questionable in this bi-phasic rain garden. The other species were suitable under the tested conditions. Careful selection of plants, including those native to Ohio, resulted in plants that grew well in the bi-phasic rain garden and provided both effective remediation of heavy-metal contaminated storm runoff and an aesthetically pleasing urban landscape.
Advisors/Committee Members: Dick, Warren.
Subjects: Environmental engineering; Environmental science; Soil sciences
Keywords: bi-phasic bioretention rain garden; runoff pollutants; heavy metals; plants native to Ohio
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9.
Florence, Darlene Christina.
Agronomic Land Management Effects on Soil Fertility and Grain Crop Productivity in Western Kenya and Ohio.
Degree: PhD, Soil Science, 2012, Ohio State University
► Soil, our planet’s most abundant natural resource, requires mindful agronomic management to…
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▼ Soil, our planet’s most abundant natural resource, requires mindful agronomic management to support an increasing world population. Soil fertility management provides a central tool to address nutrient-deficient soils and soils where excess nutrients move from the field potentially impairing the environmental. The three projects in this dissertation evaluated different aspects of agronomic decisions faced yearly by farmers in both the developed and developing world. These studies addressed both degraded and highly productive soils, and also considered soil impacts on plant productivity. All of the studies were field-based and carried out with a corn crop. The Ohio-based work was conducted on research farms in northeast, northwest and west-central parts of the state, whereas the work in Kenya was conducted in coordination with private landowners. In western Kenya, our study investigated a control plus three composted-manure placement options: spread evenly across the field and incorporated before planting (broadcast), below the seed (hole) and next to the row of seeds (banding), and no compost (control). Phosphorus availability and plant productivity were assessed for each compost placement treatment. All farm locations had soils that were moderately acidic. In terms of crop yield, the hole method tended to increase yield on the soils with low fertility, while no differences between the control and the placement treatments were observed on the moderate fertility farms. An Ohio-based study, the “Phosphorus Trial,” examined five rates of a commercial phosphorus fertilizer applied using both broadcast and banding methods. The goals of the study were to evaluate more efficient use of phosphorus, which, when eroded with soil particles or lost via fertilizer runoff, can negatively affect the environmental through impairment of water bodies and results in an economic loss to the grower. Data from two site-years revealed a higher yield for 140 kg ha-1 broadcast over the control for both site years. In one year, the highest three starter rates (140, 112, and 84 kg ha-1) all had a higher yield than the control, whereas there was no difference in the second year. The Ohio-based “Omission Trial” project was designed to allow an examination of the agronomic system responses due to the interaction of multiple land management decisions. A contrast ANOVA statistical analysis enabled a ranking of the relative importance of each management aspect in terms of lodging, yield, and yield component (number of rows per ear and number of kernels per row). Our study included seeding rate, timing of fungicide application, and the rate, timing, and placement of nitrogen and potassium fertilizers. In 2010 and 2011, there were no yield differences; however, in 2011, there was a kernel per row reduction with reduction in N from the enhanced system at one site.
Advisors/Committee Members: McCoy, Edward.
Subjects: Agriculture; Agronomy; Soil Sciences
Keywords: Zea mays; corn; maize; compost; cattle manure; Kenya; Ohio; Phosphorus placement; omission trial
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10.
Gagliano, Wendy Buell.
Biogeochemical characterization of a constructed wetland for acid mine drainage greatment.
Degree: PhD, Soil Science, 2004, Ohio State University
► Drainage from abandoned coal mines has resulted in severe water quality problems.…
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▼ Drainage from abandoned coal mines has resulted in severe water quality problems. The oxidation of sulfide minerals in coal and associated rocks releases iron-rich, acidic solutions that damage vegetation and aquatic ecosystems. The objective of this study was to characterize the sediment column of an established compost wetland constructed for the treatment of acid mine drainage to gain insight into biogeochemical processes that might impact treatment efficiency. To do this, mineralogy and geochemical stability of ochreous sediments were examined, spatial and seasonal trends in porewater chemistry were measured, and bacterial community composition profiled. The mineralogical composition of the ochre portion of the sediment column was a mixture of schwertmannite [Fe8O8(OH)4.8(SO4)1.6] and goethite (a-FeOOH). Initial drainage conditions favored the precipitation of schwertmannite, which transformed at a rate of 10-30 mol/m3/yr to goethite. The sulfide minerals, pyrite (FeS2) and greigite (Fe3S4), were identified along with magnetite (Fe3O4) in the compost layer of the sediment. Vertical gradients in porewater chemistry were similar throughout the wetland system and, with the exception of dissolved sulfide concentration, no consistent seasonal trends were detected. Dissolved sulfide was elevated in the compost relative to the ochre and in June compared to February. Porewater pH ranged from 3 to 7 and increased with depth; whereas, the Eh ranged from 110 to 750 mV and decreased with depth. Both pH and Eh changed abruptly near the interface between the ochre and compost layers. Dissolved Fe occurred primarily as Fe(II) and peaked within the interface region. Concentrations of other major elements (Al, Ca, K, Mg, Mn, and Na) in the pore waters showed some variation between cells and sampling dates, but vertical gradients generally reflected wetland stratigraphy. Terminal restriction fragment length polymorphism analysis (T-RFLP) of 16S rRNA genes was used to profile bacterial community composition. Bacterial diversity was found to be similar throughout the sediment profile; however, bacterial communities clustered together and could be correlated to sediment properties. Many terminal restriction fragment’s (TRF’s) consistent with bacteria relevant to wetland treatment efficiency were found. These included multiple TRF’s consistent with eight genera of sulfate-reducing bacteria as well as iron-reducers like Shewanella and Peleobacter.
Advisors/Committee Members: Bigham, Jerry M.
Keywords: MINE DRAINAGE; WETLAND; sediment; DRAINAGE; compost; schwertmannite; Fe
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11.
Goodman, Jenette Michelle.
Creating a Reliable and Transparent System for Updating Soil Based Yield and Productivity Data.
Degree: MS, Soil Science, 2010, Ohio State University
► Agricultural real estate taxes are assessed in the state of Ohio under…
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▼ Agricultural real estate taxes are assessed in the state of Ohio under the Current Agricultural Use Value (CAUV) program, which allows farmers to have their parcels taxed according to agricultural value, rather than full market value. Land values are assessed based soil productivity and yield potential, realizing that a farm with more productive soils has a higher yield potential and therefore greater real estate value. In order to have a fair tax assessment system, it is necessary to have accurate crop yield predictions for each soil in Ohio as well a reliable and transparent method for rating soil productivity. The goal of this study was to use existing soil and climate data to create a reliable and transparent system for generating yield and productivity data for Ohio soils. Crop models are a well tested and generally accepted method for evaluating crop yield potential. Because Ohio tax rates are based on soil type, it is important to use a crop model that fully incorporates the soil properties most responsible for yield potential. For this study, the DSSAT cropping modeling software was used to predict maize yield values for a number of soil series in Ohio. Climate, soil, and management data were used as model inputs. Soil data was compiled on a soil series basis and management was assessed at an “average” level. Two different modeling scenarios were established for which maize yields were generated.
Advisors/Committee Members: Slater, Brian.
Subjects: Agriculture; Environmental science; Soil sciences
Keywords: CSM; DSSAT; CERES; Crop Modeling
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12.
Henry, David Christopher.
Nitrogen Contribution from Red Clover for Corn Following Wheat in Western Ohio.
Degree: MS, Soil Science, 2010, Ohio State University
► Inclusion of a winter legume cover crop into a crop rotation has…
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▼ Inclusion of a winter legume cover crop into a crop rotation has been suggested as method to provide a substantial portion of the nitrogen (N) requirement of a subsequent grass crop. While the benefits of winter cover crops such as reduced soil erosion, increased soil organic matter, and increased mulch cover have been well documented, the N contribution to the subsequent crop has shown to be variable. The objective of this study is to determine the N contribution from a red clover (Trifolium pretense, L.) cover crop following wheat (Triticum aestivum, L.) to a subsequent corn (Zea mays, L.) crop. The experiment was conduct at two western Ohio locations over three years. At both locations, red clover was either interseeded into wheat or seeded after harvest, the red clover cover crop was eliminated with tillage or herbicide application, and corn was planted with three N rates (0, 90, and 180 kg N ha-1). The data revealed that for three of the four site years (when the cover crop was successfully established) there was no N contribution attributable to the presence of red clover. The one site that did show an N contribution revealed that the amount of N contributed was less than 90 kg N ha-1. However, even when no N benefit was found, yields were improved by non-N related rotational effects. Significant reductions in N fertilization rates following a red clover cover crop are likely to result in lost corn yield opportunities in western Ohio.
Advisors/Committee Members: Mullen, Robert.
Subjects: Agronomy
Keywords: cover crop, legume, nitrogen contribution
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13.
Jagadamma, Sindhu.
Stabilization mechanisms of organic carbon in two soils of the Midwestern United States.
Degree: PhD, Soil Science, 2009, Ohio State University
► The soil organic carbon (SOC) pool is very important as a potential…
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▼ The soil organic carbon (SOC) pool is very important as a potential sink of C over human time scales. In order to evaluate the potential of soils as a long-term C sink in response to changing management and climate, it is essential to be able to experimentally partition different SOC fractions. Despite many advances in the understanding of SOC dynamics, numerous uncertainties still exist in the separation of SOC fractions with distinct stability. Therefore, the overall objective of this research was to acquire a better understanding of the stable SOC fraction in terms of pool size, structural composition, and turnover rates in two soils of the Midwestern United States (Typic Fragiudalf of Wooster, OH and Aquic Argiudoll of Monmouth, IL). Both physical and chemical fractionation methods were employed to isolate the stable from labile SOC. Comparison of the commonly used chemical oxidizing agents, namely hydrogen peroxide (H2O2), disodium peroxodisulphate (Na2S2O8), and sodium hypochlorite (NaOCl), revealed that both H2O2 and Na2S2O8 are more effective than NaOCl in isolating a stable SOC fraction enriched with alkyl-C groups and a radiocarbon age of thousands of years old. Evaluation of the physical fractions indicated that (i) sand and silt-associated SOC quickly changed with conversion from native vegetation to agricultural crops, and (ii) the clay associated SOC in agricultural soils of Wooster continues to increase, albeit at a slower rate, with increase in total SOC, while it attained maximum saturation capacity in the Mollisol at Monmouth. In general, the pool size of the stable SOC fractions isolated by physical methods was significantly higher (10.7 to 64.8% of total SOC) than that isolated by chemical methods (1.3 to 25.6% of total SOC). Combining physical and chemical methods isolated a stable SOC fraction with longer stability in the surface soils than the individual methods, while the different methods did not influence substantially the turnover rates of the stable SOC pool in the subsoil. Results obtained from this study will strengthen the current knowledge on the efficiency of different fractionation methods for isolating the SOC fractions with distinct stability. Such information is very important for accurate quantification of the effects of land use or management changes on long-term stabilization of SOC, and also for the validation of SOC prediction models.
Advisors/Committee Members: Lal, Rattan.
Subjects: Soil sciences
Keywords: Soil organic carbon; fractionation methods; stable SOC; NMR spectroscopy; Radiocarbon age; 13C-natural abundance
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14.
Lane, Matthew S.
THE EFFECT OF GLYPHOSATE ON SOIL MICROBIAL COMMUNITIES.
Degree: MS, Soil Science, 2011, Ohio State University
► Glyphosate [N-(phosphonomethyl)glycine] is the most widely used herbicide in the world. First…
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▼ Glyphosate [N-(phosphonomethyl)glycine] is the most widely used herbicide in the world. First sold in 1974 under the trade name Roundup, its use has increased dramatically in recent years with the introduction of genetically modified, glyphosate resistant (GR) crops. There is growing anecdotal evidence in the Midwestern United States of potassium (K) deficiency in corn, which appears to be related to the adoption of GR soybeans grown in rotation with corn. It is possible that the use of glyphosate in GR cropping systems is creating a selection pressure in soil microbial communities which could affect soil K dynamics. The first objective of Chapter 1 was to determine the effect of rates of glyphosate on microbial respiration. The second thesis objective of Chapter 1 was to determine the effect of glyphosate on microbial community structure, exchangeable, non-exchangeable, and microbial K in soils that had no, limited, or high amounts of glyphosate exposure under field conditions. The objectives of Chapter 2 were to determine the effect of foliar glyphosate applied to GR soybean on: 1) the rhizosphere soil microbial community composition, 2) exchangeable, non-exchangeable, and microbial K; and 3) leaf concentration K. In an incubation experiment, the addition of glyphosate was shown to significantly increase microbial respiration rates. The magnitude and duration of rates of respiration were greater in soils with a previous history of glyphosate applications, indicating that previous exposure to glyphosate may be associated with an increase in organisms able to metabolize glyphosate. In a second experiment, glyphosate was applied repeatedly to soils over a 180 day period. There were no significant shifts in soil microbial community structure based on ester linked fatty acid methyl ester (EL-FAME) analysis. In addition, glyphosate application did not significantly affect microbial biomass K. In a third experiment, glyphosate resistant soybeans grown in the greenhouse were exposed to repeated glyphosate applications. Glyphosate application did cause a significant decrease in the total microbial biomass in soybean rhizosphere soil, as measured by total extracted EL-FAMEs, in the soil that had no previous exposure to glyphosate at seven days after the glyphosate application. However, no significant changes were observed in the overall microbial community structure. These studies indicated that: 1) glyphosate stimulates microbial respiration; 2) repeated glyphosate application to soil may increase populations of microorganisms able to degrade glyphosate; 3) the application of glyphosate can lower total microbial biomass in the glyphosate resistant soybean rhizosphere; 4) changes in the structural diversity of the soil microbial community due to glyphosate application were not detectible using EL-FAME profiling, and; 5) glyphosate does not appear to reduce the plant availability of K, as no significant decreases in exchangeable or plant tissue K, nor increases in microbial biomass K, were observed after glyphosate application.
Advisors/Committee Members: Dick, Richard.
Subjects: Agronomy; Environmental Science; Soil Sciences
Keywords: Glyphosate; EL-FAME; FAME; fatty acid methyl esters
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15.
Merrick, Natsuko N.
Microbial Source Tracking: Watershed Scale Study of Pathogen Origin, Fate, and Transport in the Upper Sugar Creek Watershed, Northeast Ohio.
Degree: PhD, Soil Science, 2010, Ohio State University
► The provision of safe water is one of the most important challenges…
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▼ The provision of safe water is one of the most important challenges faced by countries due to increasing populations and industrialization. Transport of non-point source pollution, including human and animal wastes, into the environment can result in pathogenic outbreaks. However, identifying the sources of non-point source pathogenic pollution is difficult, although needed if effective remediation action is to be taken. This dissertation research project describes the application of the Microbial Source Tracking (MST) method in the Upper Sugar Creek watershed, a mixed-use watershed located in northeast Ohio. Culture independent and library independent, host-specific PCR and quantitative PCR assays (human and ruminant) of the Bacteroidales 16S ribosomal RNA gene were applied to identify the source of fecal contamination in the study watershed. The effectiveness of sample processing protocols and long-term storage of environmental water samples were evaluated. Results indicated that membrane filtration for cell recovery, combined with the use of a small cell lysis container (2 mL size), produced the best efficiency and precision of DNA extraction. Long-term storage of environmental water samples before cell recovery and DNA extraction reduced DNA recovery rates. The molecular based, quantitative PCR assay was compared with the traditional viable E. coli count assay and a significant (P < 0.001) positive correlation was measured. Thus, the molecular method for measuring Bacteroidales in water samples may be used to assess potential health risk due to fecal contamination. A high magnitude of general Bacteroidales qPCR signal was observed in samples from both a concentrated livestock operation area and a residential area. Also the ruminant- and human- host specific Bacteroidales PCR assays were tested for their specificity and sensitivity with local fecal samples of potential hosts, and the result validated the use of these two host specific assays at this watershed. Frequent human specific Bacteroidales signals were also observed in water samples from a residential area. These results were followed up by a targeted sampling method at hotspots of microbial contamination within the Upper Sugar Creek watershed. The purpose of this targeted sampling was to accurately and cost-efficiently identify the source of contamination. Spatially intensive samplings during baseflow water samples revealed that the most likely major source of fecal contamination in baseflow events was human origin from septic systems. Temporally intensive samplings conducted during both surface water baseflow and stormflow conditions from suspected agricultural fecal contamination source areas indicated sediments could be a large potential reservoir of fecal contamination during stormflow events. The fate and transport of two indicator bacteria, Bacteroidales and E. coli indicated different transport behavior. The microbial source tracking (MST) method, when combined with targeted sampling, was able to identify sources of fecal contamination in a mixed-use watershed quickly, easily, accurately and inexpensively. This research demonstrates the power of the MST method and also makes it an attractive tool in studies of pathogen contamination in stream water samples.
Advisors/Committee Members: Warren, Dick.
Subjects: Environmental science; Microbiology; Molecular biology
Keywords: 16S RIBOSOMAL-RNA; REAL-TIME PCR; FECAL BACTEROIDALES; SURFACE-WATER; PERSISTENCE; BACTERIA; WATERSHED; MICROBIAL SOURCE TRACKING
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16.
Mestelan, Silvia A.
Impact of long-term no till and plow till on soil properties and soil nutrient cycling.
Degree: PhD, Soil Science, 2008, Ohio State University
► Long-term plots located at Hoytville and Wooster experimental centers (OARDC, Ohio), combine…
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▼ Long-term plots located at Hoytville and Wooster experimental centers (OARDC, Ohio), combine no-till (NT) and plow till (PT) and continuous corn (CC), corn-soybean (CS) and corn-oats-meadow (COM) on soils of contrasting properties. A poorly drained Mollic Epiaqualf is present at Hoytville, and a well drained Typic Fragiudalf dominates at Wooster. To study the impact of agricultural management (NT and PT) and less intensive land uses (wooded and grassed areas) on soil properties and nutrient cycling, pedon description and sampling was conducted at both experimental sites, including one pedon each under forest, grass, and PT and NT under corn. Standard physicochemical and mineralogical characterization and micromorphological study of thin sections were conducted. At both sites strong structure, more bioturbation with lower bulk density and increased, highly connective macroporosity were found under NT. The soil C pool (up to 31 cm) was high in the forest and NT pedons at Wooster and in forest and grassed pedon at Hoytville; PT has the lowest values at both sites. Grass and NT soils sequestered C after 40yr at Wooster but NT and PT could not reach the original C value at Hoytville. Two others studies were conducted analyzing soil samples from the last two decadal soil samplings of the experiments to track the evolution of main soil nutrient concentrations, C and N pools and pH as affected by the mentioned tillage-crop rotations. At both sites C and N concentration and C and N pools were higher under CC and COM than CS due to the reduced amount and high decomposable residues. Carbon and N concentrations and C and N pool values were higher with NT than PT at both sites; C content and C pools stabilized with NT and increased with PT at the second sampling. At both sites under CS and COM the soils had higher pH and extractable bases related to lower N fertilizer rates and greater cation recycling by roots and residues. Cation retention was greater for NT than PT; soil available P was heavily stratified under NT in both soils, increasing concerns of environmental degradation at the Hoytville site.
Advisors/Committee Members: Smeck, Neil E.
Subjects: Agriculture, Agronomy
Keywords: Poorly and well drained soils; Long-term experiments; Ohio; No-till; Plow till; Continuous corn; Soybean; Alfalfa; Soil physicochemical properties; Nutrient cycling
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17.
Mishra, Umakant.
PREDICTING STORAGE AND DYNAMICS OF SOIL ORGANIC CARBON AT A REGIONAL SCALE.
Degree: PhD, Soil Science, 2009, Ohio State University
► The pedologic C pool comprises of soil organic C (SOC) and soil…
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▼ The pedologic C pool comprises of soil organic C (SOC) and soil inorganic C (SIC) components. Of the two components, the SOC pool is a strong determinant of numerous ecosystems services. Estimates of SOC pool and their spatial variability in terrestrial ecosystems are essential to estimate the soil C sink capacity, and to quantify the amount of SOC sequestered in a defined time period. But the amount of C stored in the soil per unit area is highly variable as the magnitude of SOC pool at a location depends on a range of factors such as soil type, land use, annual input of biomass C, topographic features, and climatic conditions. These factors differ among locations and ecoregions. Consequently, several approaches are needed to develop a reliable estimate of SOC pool at different spatial scales. Therefore, the overall goal of this study was to understand the storage and dynamics of SOC pool at a regional scale. Specific objectives were to; develop methodology to quantify the SOC pool within different depth intervals at a regional scale, use environmental variables for regional scale SOC predictions, and assess the effect of tillage practices on the storage and dynamics of SOC in contrasting agricultural soils.Three studies were conducted to meet the above mentioned objectives in Midwestern United States (Ohio, Michigan, Indiana, Kentucky, Pennsylvania, West Virginia and Maryland). Soil legacy databases maintained by National Soil Survey laboratory, Pennsylvania State University, The Ohio State University, and field collected soil samples were used in this study. Environmental variables covering the study area were collected from secondary databases. Soil and environmental databases were assembled in geographic information system to develop spatially explicit models. Various univariate and multivariate mathematical, statistical and geostatistical methods including SOC profile depth distribution functions, ordinary kriging, regression kriging, analysis of variance, multiple linear regression, and geographic weighted regression techniques were used to synthesize meaningful conclusions about the SOC sequestration and dynamics at a regional scale. Results indicated that SOC pool estimates for regional scales within desired depth intervals can be made by using the exponential soil depth functions at SOC profiles and interpolating the coefficients of exponential functions. This method of predictive mapping is especially useful in scenarios where there are missing observations for some horizons as they can be interpolated using the exponential equations. Similarly, by converting conventional till to no till agriculture, some of the depleted historic SOC pool can be resequestered. In addition to environmental concerns, such a strategy can also create economic opportunities for farmers through C trading. Likewise, by using the range of spatial autocorrelation in SOC data in a geographic weighted regression (GWR) framework, better estimates of SOC pools can be made at large spatial scales. Though it is unlikely that a single model can be developed to be applicable to all soil landscapes in regional scale studies, GWR approach can play a vital role in improving the prediction ability of SOC pools across the regional scales and this methodology can be used readily by the land managers.
Advisors/Committee Members: Lal, Rattan.
Subjects: Soil sciences
Keywords: soil organic carbon, prediction, kriging
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18.
Mulumba, Lukman Nagaya.
Land use effects on soil quality and productitivity in the Lake Victoria Basin of Uganda.
Degree: PhD, Soil Science, 2004, Ohio State University
► Soil quality indices are useful tools for assessing agronomic/ biomass productivity and…
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▼ Soil quality indices are useful tools for assessing agronomic/ biomass productivity and ascertaining temporal changes in soil properties in relation to land use and management. This study was conducted in the Lake Victoria region in Masaka, Uganda to: (a) identify key soil properties that impact soil quality and agronomic productivity; (b) evaluate soil quality-management inter-relationships; (c) evaluate the use of soil reflectance as a soil quality indicator, and (d) determine the cost and returns of different cropping systems. Bulk and core soil samples were collected from the 0-20 and 20 – 50 cm depths, from the farmers’ fields, in order to determine soil organic carbon, nitrogen, calcium, phosphorous, magnesium, pH, _13C, _15N, coarse fragments, soil bulk density and soil texture. Saturated hydraulic conductivity (Ks) was determined in the field using a tension infiltrometer and soil depth using an auger. The soil degradation rating was assessed by assigning parametric values to levels of SOC, soil bulk density, Ks, soil texture, soil pH, soil depth and the proportion of coarse fragments in the top soil and these parameters were utilized to develop a single index. Air dry samples were scanned using a spectrometer and the first derivative of the spectral data was calibrated against the measured soil properties. Results indicated that soil quality was affected by SOC, soil depth and Ks. No direct effects of management on soil quality were discerned. Good predictions of several soil properties were obtained using the spectral data. Although a majority of farmers planted bananas as the first choice crop, the highest net returns were obtained from coffee while the highest costs were measured for bananas implying that food self sufficiency was the major determinant of the choice of crop to be grown. It was recommended that grasslands must not be converted to agricultural land use because of their high susceptibility to soil degradation and that farmers be sensitized to think beyond food-self sufficiency, a goal that could also be achieved through strategies which increase farm income.
Advisors/Committee Members: Lal, Rattan.
Keywords: Soil quality; Land use; Lake Victoria; Spectroscopy; Tension infiltrometer; Soil degradation; Spectral calibration; Soil organic carbon; Delta 13 carbon; soil erosion; Bananas; Grasslands; Coffee; Masaka
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19.
Ringler, Joseph William.
MONITORING THE HYDROLOGY OF SOILS FOR ON-SITE WASTEWATER TREATMENT SYSTEMS USING MATRIC POTENTIAL SENSORS.
Degree: MS, Soil Science, 2009, Ohio State University
► In the Ohio landscape, saturated soils can be problematic to the functions…
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▼ In the Ohio landscape, saturated soils can be problematic to the functions of on-site wastewater treatment systems. A method was developed to monitor the wetting and drying cycles of soils used for wastewater treatment. The method included inserting matric potential sensors and installing water table wells with minimal disturbance to the soil of a leach field wastewater absorption system. To reduce disturbance a rectangular cross section soil sampler was constructed to collect a soil core sample, a matric potential sensor was inserted into the core sample, and the core sample was placed back into the original location. The sensors provide a record of the soil matric potential over time. Some soils once considered unsuitable for wastewater treatment may be suitable if wastewater is distributed at a time when the soil is not saturated. Future systems may utilize soil moisture sensor to activate wastewater distribution at the right condition.
Advisors/Committee Members: Slater, Dr. Brian K.
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20.
Roy Chowdhury, Taniya.
Tracking Carbon Flow during Methane Oxidation into Methanotrophs using 13C-PLFA Labeling in Pulsing Freshwater Wetlands.
Degree: PhD, Soil Science, 2012, Ohio State University
► Methane (CH4) is a critical greenhouse gas with ~ 25 times greater…
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▼ Methane (CH4) is a critical greenhouse gas with ~ 25 times greater global warming potential than carbon dioxide. As the largest natural source of CH4, wetlands have faced a setback in the global warming scenario. Manipulation of wetland hydrology can be a potential management strategy to enhance CH4 consumption (by microbial oxidation) from constructed and managed wetlands. Although work in pure cultures have shown the importance of methane oxidizing bacteria (methanotrophs) in regulating net CH4 flux, few field based studies have been done on the microbial ecology of these CH4 oxidizing communities and how they respond to differing land management systems. For example, there is considerable interest in enabling current wetlands and creating wetlands that have hydrologic pulsing that is driven by seasonal rainfall and watershed dynamics. However, little is known about the ecology of methanotrophs in the “pulsing fringe” - the oxic sediment-water interface of wetlands. The objective of this study was to characterize the functionally active methanotroph communities and link them to potential methane oxidation rates in response to pulsing wetland hydrology and seasonally induced changes in redox conditions. 13C-CH4 stable isotope probing of biomarker Phospholipid Fatty Acids (PLFAs) was successfully used to track the 13C flow into the methanotroph community. Identification and quantification of methanotrophs was effectively achieved to link bacterial structure and function. The results show that, in addition to methanotrophy being controlled by environmental factors such as soil water content, oxygen and methane availability, the physiology of the microorganisms themselves can be uniquely adapted to extant conditions and potentially influence process rates. Results from this study demonstrate that seasonally pulsed wetlands have greater diversity of methanotrophs under elevated methane concentrations. In comparison, methane oxidation in the permanently flooded site was solely driven by a specialized group of methanotrophs. This study provides fundamental information for developing pulsing wetlands system that facilitates greater taxonomic diversity of methanotrophs and methanotrophy.
Advisors/Committee Members: Dick, Richard.
Subjects: Biochemistry; Biogeochemistry; Ecology; Environmental Science; Geochemistry; Microbiology; Soil Sciences
Keywords: Phospholipid fatty acids, Soil, Methanotrophs, methane, wetland hydrology, methane oxidation, stable isotope probing, methanotrophs, freshwater wetlands, wetland management, flow-through incubation
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22.
Subburayalu, Sakthi Kumaran.
Application of machine learning for soil survey updates: A case study in southeastern Ohio.
Degree: PhD, Soil Science, 2008, Ohio State University
► Machine learning techniques were used to build predictive soil-landscape models for two…
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▼ Machine learning techniques were used to build predictive soil-landscape models for two counties (Monroe and Noble) in southeastern Ohio. Twenty five different environmental correlates including 10m resolution raster coverages of terrain and its derivatives, climate, geology, and historic vegetation were used as predictor variables for soil class. Randomly sampled points proportionate to the area of the different soil classes from the published soil survey of Monroe County (SSURGO) were used to train the soil-landscape model. Since map units can contain more than one component soil series, each sample point within a map unit can possibly belong to any one of them. Hence there is ambiguity in labeling of the training instances with appropriate soil series. A kNN-based heuristic approach was used to disambiguate the training set labels. The training sets were further preprocessed for removal of outliers and for selection of fewer attributes. Modeling was performed using two learning algorithms namely J48 classification tree and Random Forest (RF). The map models were then evaluated for the quality of prediction using two prediction rate measures and two landscape fragmentation statistics. Generally Random Forest recorded a higher prediction rate and greater contiguity when compared to J48. However, Random Forest over predicted soils such as Gilpin, Guernsey, Zanesville and Captina Series which occupy large areas, at the cost of prediction accuracy of soils which occurred in smaller proportions. The results showed that the highest prediction rate based on the dominant soil series (> 0.5) and higher values of contiguity index (0.83) and aggregation index (84.2) for RF was observed in the model built using the training set preprocessed for disambiguation. This suggests an improvement in the quality of predicted maps as a result of disambiguation. The model predictions were helpful in locating many individual component series in soil consociations and associations. The maps were useful in identifying areas of uncertainty such as misplacement of polygon boundaries, incorrect labeling and disparity along the county edges, which could serve as a guide for further field investigations. The predicted models also provided valuable information for rationalizing the mapping intensity for adjacent SSURGO maps.
Advisors/Committee Members: Slater, Brian K.
Subjects: Agriculture, Soil Science
Keywords: machine learning; data mining; soil survey; SSURGO updates; soil-landscape modeling; predictive soil modeling; Random Forest
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23.
Tirado-Corbala, Rebecca.
A Lysimeter Study of Vadose Zone Porosity and Water Movement in Gypsum Amended Soils.
Degree: PhD, Soil Science, 2010, Ohio State University
► In Ohio, approximately 55% of agricultural land needs drainage to overcome occasional…
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▼ In Ohio, approximately 55% of agricultural land needs drainage to overcome occasional water ponding, reduce soil erosion, improve fields to support farm equipment and reduce crop yield variability. In recent years, many Ohio farmers converted to non-tillage systems without understanding the system constraints especially on poorly drained soils. Due to Ohio being a major coal-burning state for electricity production, enormous amounts of coal combustion by-products such as gypsum are readily available for agricultural use. Gypsum is a source of calcium which may improve the physical properties of the soil by promoting soil aggregation, increasing water surface infiltration rates and movement into and through the soil profile. Several studies in the Midwest have focused on the effect of gypsum controlling surface structure, crusting, sealing and erosion. However few studies have analyzed the structural and hydrologic effects of gypsum on the whole profile of non-sodic soils, especially in subsurface horizons.For that reason, undisturbed soil columns from Brookston loam and Celina silt loam soils with different gypsum application regimes were collected to determine the effect of gypsum on physical-chemical soil properties and hydrology of these two non-sodic soils with contrasting drainage from no-till fields. Higher exchangeable calcium and Ca:Mg ratios were found on both gypsum treated soils. Soil turbidity and light transmittance studies showed a positive effect with respect to gypsum application rate. Clearer suspensions and higher light transmittance were found under long-term gypsum. However, there was no consistent response for gypsum application regimes in both soils for water stable aggregates, water stable aggregates by aggregate size and mean weight diameter on the whole soil profile. Positive gypsum effects on both Brookston treated soils were observed. Greater water stable aggregates were found for > 4mm aggregates in the top 60 cm of short-term gypsum treatments and 60-75 cm interval of long-term gypsum treatments. However, in Celina, higher mean weight diameter and water stable aggregates were found for both gypsum treatments. Greater water stable aggregates occurred for > 4 mm aggregates in the top 40 cm of soil. Also, greater drainage (~ 60%) was obtained under Brookston long-term gypsum and Celina short-term gypsum soils. Greater drainage response on Brookston long-term gypsum was attributed to calcium redistribution to lower depths. Restricted drainage on Celina long-term soils was attributed to secondary calcium carbonate precipitation in pores.
Advisors/Committee Members: Slater, Brian.
Subjects: Soil Sciences
Keywords: gypsum; flue gas desulfurization gypsum; micromorphological analysis; thin sections; flocculation studies; Ca:Mg ratio; lysimeter study; aggregate stability
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24.
Undercoffer, Jason.
Monitoring Phosphorus Transport and Soil Test Phosphorus From Two Distinct Drinking Water Treatment Residual Application Methods.
Degree: MS, Soil Science, 2009, Ohio State University
► Applications of manure and soils with elevated amounts of phosphorus (P) can…
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▼ Applications of manure and soils with elevated amounts of phosphorus (P) can result in surface transport of P leading to eutrophication of surface waters. Drinking water treatment residuals (WTR) have been identified as a potential best management practice to reduce the loss of P from agricultural fields. Two field simulated rainfall studies were used to investigate the efficacy of WTR to reduce P transport, reduce soil test P (STP), and determine if relationships between STP and runoff dissolved P (RDP) are altered by soil applied WTR. In the first field study, WTR was co-blended with poultry litter to achieve a range of phosphorus to aluminum molar ratios, or phosphorus saturations (Psat), two weeks prior to land application. Blending WTR at rates of 0, 7, 21, 84 g WTR kg-1 manure resulted in phosphorus saturations of 1860% (0WTR), 600% (LWTR), 200% (MWTR) and 50% (HWTR), respectively. Manure soluble P was reduced by 33, 62, and 96% by the LWTR, MWTR, and HWTR, respectively. The treatments were broadcast at 11.3 Mg ha-1 on field plots (2m X 2m) and simulated rainfall was performed prior to, immediately following application and at 1 month intervals for 3 months. Immediately following treatment application, RDP was reduced by 68% by the MWTR treatment and 97% by the HWTR treatment when compared to the RDP of the 0WTR treatment (32.9 mg L-1). These large reductions relative to previous research suggest co-blending WTR with manure prior to land application, rather than broadcasting each material separately, may be a more effective use of WTRs P-binding capability. Currently, Ohio’s P-index uses total manure P as an indicator of P transport risk. Results of this study show that the P-index should be adjusted for WTR treatments. Phosphorus source coefficients determined by soluble manure P is currently used by several states and could be used in Ohio to reflect reduced P transport from WTR co-blending. Co-blending WTR with manure to achieve a final blended Psat < 100% may provide the best protection of water quality and be a useful tool for WTR/manure co-blending calibration. In the second field simulated rainfall study, WTR (10 Mg ha-1) was incorporated into field plots (2m x 2m) with a wide STP range. Soil incorporated WTR reduced STP for all soil test methods following WEP (74.8%) > Psat (50.2%) > M3P (40.2%) > B1P (39.5%) and RDP (39.4%), one day after WTR application. We observed positive linear relationships between Mehlich-3 P (M3P), Bray-1 P (B1P), water extractable P (WEP), and phosphorus saturation (Psat) with RDP for all runoff events. Relationships between M3P, B1P, or Psat and RDP were not significantly altered by soil incorporated WTR while the relationship formed by WEP and RDP had a significantly higher slope when soil incorporated WTR was present. Ohio’s P-index currently utilizes B1P and M3P as an indicator of environmental risk of P transport. Results from this study support the use of B1P and M3P to categorize P transport risk, regardless of previous WTR applications.
Advisors/Committee Members: Basta, Nicholas.
Subjects: Soil sciences
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25.
Weatherington-Rice, Julie Bishop Paynter.
Fracture occurrence and ground water pollution potential in Ohio's glacial and lacustrine deposits: a soils, geologic, and educational perspective.
Degree: PhD, Soil Science, 2003, Ohio State University
► This dissertation consists of five journal articles. The first two attempt to…
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▼ This dissertation consists of five journal articles. The first two attempt to answer two critical questions relating to the basic understanding of fracture flow: how quickly do fractures form, how long do they persist? Fractures form very quickly in fill materials from Ohios glacial tills and lakebeds. This discovery raises concern regarding the use of Ohios fine-grained glacial and lacustrine materials in the built environment. The second documents that fractures, once formed, remain indefinitely, unless the materials are eroded away. This discovery is supported by the presence of Green Rust in buried lacustrine materials found in bedrock valleys in Clermont County, Ohio. The Green Rust iron composition is so unstable that when exposed to oxygen, it turns to goethite, yet it has been preserved in its unstable state since the last polar reversal. Water moves in fractures and along bedding planes. Ohio Department of Natural Resources (ODNR), Div. of Water modified their Ground Water Pollution Potential, (DRASTIC) mapping program in 1995. The third paper presents a short history of US EPAs DRASTIC methodology, observations, and philosophical decisions that led ODNR to modify their application of the DRASTIC process. The fourth paper provides an independent evaluation of 21 sites in Ohio where fractures have been identified from boring samples, backhoe pits and stream cuts. The review of these sites confirms 23 of the soils from Tornes and others (2000) and identifies four more. These 27 soils represent almost 8 million acres in Ohio, over 14 million acres in the Midwest. The paper confirms ODNRs modification of DRASTIC mapping, and cautions land-use practices on these soil settings. The fifth paper focuses on an Ohio Fracture Flow Working Group activity, a Field Day held at OSUs Farm Science Review facility, and presents a short history of the use of outdoor sites for educational purposes. Four more field days have been held around Ohio; more are planned.
Advisors/Committee Members: Hall, George F.
Keywords: fracture flow; glacial tills and lakebeds; fracture formation; formation time; green rust; DRASTIC; DRASTIC history; DRASTIC modification; fractured till confirmation; fractured soil confirmation; outdoor education; professional education; field day
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26.
Whitacre, Shane D.
Soil Controls on Arsenic Bioaccessibility: Arsenic Fractions and Soil Properties.
Degree: MS, Soil Science, 2009, Ohio State University
► In vitro gastrointestinal methods can potentially provide a rapid and inexpensive measure…
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▼ In vitro gastrointestinal methods can potentially provide a rapid and inexpensive measure of bioaccessible arsenic which in turn can be used to conduct more accurate and site-specific human health risk assessments of contaminated soils. However, in order for in vitro methods to become widely accepted as tools that accurately assess soil As exposure through the oral ingestion pathway, a better understanding of the fractions of soil arsenic that are measured by the in vitro extraction and the underlying soil properties associated with As bioaccessibility (BA) are needed. In this study, nineteen soils with a wide range of soil properties were spiked with 250 mg/kg As. Bioaccessible As was then determined using The Ohio State University in vitro gastrointestinal method (OSU-IVG) and soil As was fractionated using a four-step sequential extraction. There was a wide range in As BA; from 27.3 to 206 mg/kg with a mean of 94.7 mg/kg in the gastric phase, and from 29.0 to 210 mg/kg in the intestinal phase with a mean of 98.6 mg/kg. Highly significant (P < 0.0001) relationships existed between bioaccessible As and the combination of soil pH and Fe extracted by citrate bicarbonate dithionite (Fecbd) or soil pH and Fe extracted by acid ammonium oxalate (Feox). Soil pH explains more of the variation in bioaccessible As (r2 = 0.67) than Fecbd (r2 = 0.45) or Feox (r2 = 0.38). The sequential extraction results indicate that As extracted from non-specifically sorbed (F1) and specifically sorbed (F2) fractions provide a good measure of pH and iron oxide (Fecbd and Feox) controlled As BA (GE, r2 = m = 1.06; IE, r2 = 0.94, m = 1.07). However, the addition of amorphous or poorly-crystalline oxides of Fe (F3) and well-crystallized oxides of Fe (F4) as extractable As fractions to F1 and F2 dies not improve the correlation with bioaccessible As. Therefore, the total As content of soil overestimates and is a poor indication of bioaccessible As. The largest contribution to bioaccessible As is the specifically sorbed (F2) fraction of soil As. Because F2 As is the largest contribution to bioaccessible As, it is the strong linear relationship between F2 and soil pH that controls the relationship between bioaccessible As and soil pH. Accurate and site specific HHRAs are necessary in order to prevent the use of overly conservative assumptions that would result in unnecessary site remediation. The use of As BA in HHRA as determined by valid in vitro methods supported by soil property and As fractionation results could potentially provide enormous cost and time savings for superfund site managers while assuring protection to public health.
Advisors/Committee Members: Basta, Nicholas.
Subjects: Environmental science
Keywords: Arsenic; Arsenate; soil properties; fractionation
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27.
Yousef, Lina Fayez.
Class-I Elicitins in Relation to Sterol Acquisition and Lipid Profiling of Phytophthora sojae.
Degree: PhD, Soil Science, 2010, Ohio State University
► Soybean plants can be attacked by the soilborne pathogen Phytophthora sojae at…
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▼ Soybean plants can be attacked by the soilborne pathogen Phytophthora sojae at all growth stages and may result in damping-off of seedlings, root and stem rots; all of which cause significant losses in soybean harvestable yield. To gain a better understanding of the biology and ecology of Phytophthos sojae, and for the purpose of developing novel disease management practices, this Phd dissertation investigated two major themes: (1) The biological role of elicitins as sterol carrier proteins in P. sojae: and (2) Development of a cellular lipid profiling method as a basis for determining infestations of P. sojae in soil. The first theme investigated extracellular proteins belonging to class-I elicitins in Phytophthora. It is presumed elicitins may be involved in sterol acquisition, but very little is known about the relationship between sterols and elicitin gene expression. The objective was to determine the pattern of class-I elicitin gene expression in P. sojae, when its growth medium contains different types of sterol (fungal, plant or animal). It was discovered that the growth of P. sojae was stimulated by nanomolar concentrations of all the sterols tested. This also resulted in a differential regulation of class-I elicitin gene expression compared to controls when monitored over-time using real time Reverse Transcription Polymerase Chain Reaction (RT-PCR). Generally, class-I elicitin genes became down-regulated over time which also coincided with a reduction in elicitin biosynthesis when any of the sterols was present in the growth medium. However, kinetics of down-regulation varied as a function of sterol structure, which may be related to binding efficiencies for sterols with elicitins. Also, using Elemental Analysis-Isotopic Ratio Mass Spectrometry (EA-IRMS) I discovered that P. sojae rapidly assimilated 15N-labeled extracellular proteins (which predominantly constitute class-I elicitins) into its mycelium. This happened when stigmasterol was added to the growth medium, suggesting that elicitins are involved in sterol sequestration by this organism. This study is the first to show that sterols regulate the expression of class-I elicitin genes in Phytophthora which provide strong evidence for the involvement of elicitins in sterol acquisition. The second theme of this dissertation was on the development of a biochemical assay to detect P. sojae infestation in soil. The approach was based on profiling total cellular Fatty Acid Methyl Esters (FAME) of P. sojae in pure culture. A total of 12 fatty acids (14:0, 16:0, 18:0, 16:1 ω7, 18:1 ω9, 18:2 ω6, 18:3 ω6, 20:1 ω9, 20:3 ω6, 20:4 ω6, 22:1 ω9 and 24:1 ω9) were identified in the FAME profiles of P. sojae pure cultures. The predominant fatty acids in the FAME profiles are the unsaturated 18C fatty acids (18:1ω9 and 18:2 ω6) followed by the saturated and unsaturated 16C fatty acids (16:0 and 16:1 ω7). Zoospores of P. sojae additionally contained the long-chain saturated fatty acids (20:0 and 22:0), which were not detected in the mycelium of this organism. The potential of using FAME profiles of P. sojae for detecting the pathogen in soil was evaluated by adding a known number of zoospores of P. sojae to soil. The results showed that fatty acids such as 18:1w9, 18:2w6, 20:1w9, 20:4w6 and 22:1w9 could be detected and quantified against the background levels of fatty acids present in soil. This outcome is significant because it offers the potential for a simple and rapid method for determining P. sojae infestations in soil.
Advisors/Committee Members: Dick, Richard P.
Subjects: Biology; Plant pathology; Soil sciences
Keywords: Phytophthora, elicitin, sterol-carrier proteins, Fatty Acids, Soybean, sterol, zoospore
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28.
Zinn, Yuri Lopes.
Textural, mineralogical and structural controls on soil organic carbon retention in the Brazilian Cerrados.
Degree: PhD, Soil Science, 2005, Ohio State University
► Soil organic carbon (SOC) retention results from climate, vegetation, drainage and management…
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▼ Soil organic carbon (SOC) retention results from climate, vegetation, drainage and management interactions, but also from texture, mineralogy and structure. In order to assess the controls that these three soil properties exert on SOC levels in the Brazilian Cerrado region, three native soils under similar climate and slope but of contrasting texture were sampled in triplicate to 1m depth. Soils were characterized by physical, chemical, mineralogical, wet sieving, and microscopic analyses, and SOC concentration was determined in bulk soils, particle size separates (clay, silt, sand) and water-stable aggregates (WSA). The basic assumption was that SOC particle size determines its retention mechanism: colloidal forms are sorbed to clays, and particulate organic matter (POM, >20ìm) occurs outside (free-POM) or inside aggregates (occluded-POM). These mechanisms are affected by soil texture, mineralogy and structure, which then control SOC retention. The three soils were classified as kaolinitic clayey, loamy and sandy Haplustox. Soil texture and depth strongly affected SOC concentrations, which were modeled (R2=0.92, n=126) based on clay+silt and depth. Soil specific surface area (SSA) was modeled as a function of clay, silt and SOC contents, but not depth. Thus, SOC increased with higher SSA and clay; but in a single soil profile SSA decreased in topsoil because of SOC-enhanced aggregation. SOC concentration in size separates was inversely related to the amount of that size fraction in soil (SOC dilution effect), but the clay-sized SOC pool could be modeled as a function of clay contents and depth. The bulk SOC and clay-sized SOC pool were better correlated with Fe-oxides in topsoil and amorphous Al oxides in the subsoil. Soil structure, as indicated by mean weight diameter (MWD) and percent of WSA>2 mm, was strongly correlated with clay+silt contents, but bulk SOC was poorly correlated structure, except for the 0-5 cm depth. Occluded-POM was strongly affected by soil texture, varying from ca. 25% of total POM in the sandy Haplustox, to ca. 50% in the clayey Haplustox. Because texture affects contents of Fe-Al oxides and POM occlusion, SOC retention in Cerrado soils is controlled, in decreasing order, by: 1) texture, 2) mineralogy, and 3) structure.
Advisors/Committee Members: Lal, Rattan.
Keywords: Soil Organic Carbon, Texture, Mineralogy, Structure, Fauna, Brazil, Cerrado
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29.
Zirkle, Gina N.
Assessment of Carbon Sequestration in the U.S. Residential Landscape.
Degree: MS, Soil Science, 2010, Ohio State University
► Since the industrial revolution, atmospheric concentrations of CO2 (carbon dioxide) have been…
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▼ Since the industrial revolution, atmospheric concentrations of CO2 (carbon dioxide) have been increasing. To mitigate or slow the accession of CO2, research in the areas of terrestrial and soil C (carbon) sequestration is on the rise. This study focuses on the potential of residential landscapes to sequester C. Urbanized land covers approximately 40.6 Mha (million hectares) in the U.S with approximately 41% of the U.S. urban areas are used for residential neighborhoods. As urbanization increases, the percentage of land converted into residential homes and landscapes is also increasing. Turfgrasses are common in urban areas and cover 16 – 20 Mha in the U.S. which includes residential, commercial, and institutional lawns, parks, golf courses, and athletic fields. Home lawns constitute approximately 6.4 Mha of this turfgrass area. In this study tree, shrub, and lawn C sequestration rates are estimated based on 80 million U.S. single family residential homes with a residential lot size of 2,000 m2. A typical US home is 93 m2 with a 2-car garage or carport size of 38 m2 and a deck or patio of 38 m2. The house is assumed to be sited in the middle of the lot, with a driveway size of 168 m2 and a sidewalk size of 122 m2. The remaining area of 1,541 m2 is landscape. The first model estimates the influence of home lawns on net soil organic carbon (SOC) sequestration taking into account the hidden carbon costs (HCC) of fertilizer, mowing, irrigation, and pesticide applications. SOC sequestration and HCC data rates are established from literature. The net SOC sequestration rate is assessed by subtracting the HCC from gross SOC sequestered. Lawn maintenance practices range from low to high management. Low management or minimal input (MI) includes mowing only, with a net SOC sequestration rate of 63.5 – 69.7 kg C lawn-1 yr-1. Do-It-Yourself (DIY) management by homeowners is 107.7 – 124.8 kg C lawn-1 yr-1. High management is based on university and industry-standard best management recommendation practices (BMPs) and has a net SOC sequestration rate of 85.3 – 142.9 kg C lawn-1 yr-1. The next model uses the SOC sequestration rates from the previous model and incorporated trees and shrubs using two landscape regimes. The first model has a minimal landscape with one landscape bed in the front of the house 13 m long containing 5 – 10 shrubs approximately 0.6 – 1.2 m in length and width, 2 trees, and a minimal managed lawn. The second model has a maximum landscape with several landscape beds 43 m long surrounding the perimeter of the house containing 17 – 25 shrubs approximately 0.6 – 1.2 meters in length and width, 6 trees, and highly maintained lawn. Tree sequestration rates are determined by average sequestration rates available from literature and the size of the 10 most common species found in the U.S. shrub sequestration rates are a fraction of that to trees based on relative canopy size. Total or gross C sequestration rate for trees are 3.4 – 5.9 kg C tree-1 yr-1and 0.07 – 0.24 kg C shrub-1 yr-1. A minimal landscaped yard sequesters 111.5 – 139.4 kg C yard-1 yr-1. Approximately 7.4% is sequestered by trees, 1.1% by shrubs, and 91.5% by the lawn. A maximum landscape yard sequesters 110.9 – 262.8 kg C yard-1 yr-1 with 14.9% from trees, 2.6% by shrubs, and 82.5% by the lawn. Results support the conclusion that residential landscapes are a positive net sink for atmospheric CO2 under all evaluated levels of landscapes. Even though there are HCC associated with lawn management practices, the potential for soils to sequester C may offset these costs. Residential landscapes have a significant influence on the C cycle. Therefore, these landscapes should be included in regional, national, and global C budget estimations.
Advisors/Committee Members: Lal, Rattan.
Subjects: Agriculture; Soil sciences
Keywords: Turfgrass managment; C sequestration; Hidden carbon costs; Carbon equivalents; lawns
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