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Full-Text Articles in Physical Sciences and Mathematics

The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick Jan 2008

The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick

Retrospective Theses and Dissertations

Corn stover represents a potential lignocellulosic feedstock that may benefit the emerging cellulosic ethanol industry. This study was conducted to determine dry matter yield and quality characteristics of maize stover, cob, and husk plant fractions, and to make predictions of potential ethanol yields. Detergent fiber predictions were made for each plant fraction using near infrared reflectance spectroscopy (NIRS). Predicted values were used to determine ethanol potential using a modified version of the National Renewable Energy Lab (NREL) theoretical ethanol yield calculator. Although significant, not as much variation was present among genotypes and plant fractions for chemical composition as for dry ...


The Effects Of Farmer Attitudes And Farm Management Practices On Soil Quality: A Study In Cherokee County, Iowa, Amber D. Anderson Mba Jan 2008

The Effects Of Farmer Attitudes And Farm Management Practices On Soil Quality: A Study In Cherokee County, Iowa, Amber D. Anderson Mba

Retrospective Theses and Dissertations

This study seeks to relate farmer attitudes, perceptions, and management characteristics to field soil quality and laboratory fertility indicators. Farmer interviews were conducted to document recent practices on the farm as well as farmer attitudes about farming. To obtain soil quality measures, both the Natural Resource Conservation Service's field soil quality kit and laboratory tests were employed. Sites from the eastern half of Cherokee County, Iowa, were selected.;Key considerations of this study included farmer practices of renting versus owning land and organic or synthetic nitrogen application. Additional farmer data, including attitudes about farming, are used in this analysis ...


A Simulation Assessment Of The Boone River Watershed: Baseline Calibration/Validation Results And Issues, And Future Research Needs, Philip Walter Gassman Jan 2008

A Simulation Assessment Of The Boone River Watershed: Baseline Calibration/Validation Results And Issues, And Future Research Needs, Philip Walter Gassman

Retrospective Theses and Dissertations

A SWAT modeling framework has been constructed for the Boone River Watershed (BRW) in north central Iowa, to support further testing of SWAT and analyses of alternative management practice and/or cropping system scenarios. The BRW covers over 237,000 ha and is an intensively cropped region dominated by corn and soybean production. Nitrate losses are of particular concern in the BRW, especially through subsurface tiles that drain the predominantly flat landscapes that persist throughout the watershed. The modeling system features an intensive set of management, land use, and soil data developed at the Common Land Unit (CLU) level. The ...


Nitrous Oxide And Methane Fluxes In Riparian Buffers And Adjacent Crop Fields, Dong-Gill Kim Jan 2008

Nitrous Oxide And Methane Fluxes In Riparian Buffers And Adjacent Crop Fields, Dong-Gill Kim

Retrospective Theses and Dissertations

Denitrification is recognized as the major mechanism for reducing nitrate (NO3-) in riparian buffers and thus diminishing non-point source pollution (NPS) of surface water bodies subject to high N loads. However, increasing denitrification rates in riparian buffers may be trading the problem of NPS pollution of surface waters for atmospheric deterioration and increased global warming potential because denitrification produces nitrous oxide (N2O), a greenhouse gas also involved in stratospheric ozone depletion. Also N2O produced in the denitrification process can be dissolved in groundwater and is eventually emitted into the air when groundwater flows into a stream or a river. Riparian ...


Identification, Evaluation And Quantification Of Vocs As Biosecure Markers Of Swine Carcass Degradation, Neslihan Akdeniz Jan 2008

Identification, Evaluation And Quantification Of Vocs As Biosecure Markers Of Swine Carcass Degradation, Neslihan Akdeniz

Retrospective Theses and Dissertations

Swine carcasses were composted using passively-aerated composting system designed by the Canadian Food Inspection Agency during the 2004 Avian influenza outbreak in British Columbia. In this system, swine carcasses were fully covered by plastic sheets due to biosecurity concerns and visual inspection of the swine carcasses was impossible. Monitoring volatile organic compounds (VOCs) released from carcasses was a promising approach to assess progress and completion of the carcass degradation. In this study, VOCs were sampled using solid phase microextraction (SPME). Samples were analyzed using multidimensional gas chromatography-mass spectrometry (MDGC-MS) (a) to develop a comprehensive chemical library of volatile organic compounds ...


Integrating Qtl Analysis Into Plant Breeding Practice Using Bayesian Statistics, Shengqiang Zhong Jan 2008

Integrating Qtl Analysis Into Plant Breeding Practice Using Bayesian Statistics, Shengqiang Zhong

Retrospective Theses and Dissertations

Plant breeders face the challenges to incorporate significant developments in Bayesian quantitative trait locus (QTL) analysis into breeding practice. The overall objective of this dissertation is to integrate QTL analysis into marker-assisted selection (MAS) in plant breeding using Bayesian statistics. Three different perspectives were studied: identification of optimal designs to generate multiple families for QTL mapping, cross prediction using QTL analysis results, and genomic selection for cultivated barley. First, the impact of two mating designs was studied on QTL mapping in multiple families generated by crosses between multiple inbred lines, using within-family linkage disequilibrium (LD) with a Bayesian variable selection ...


Grassland Bird Abundance And Nesting In Short-Duration Rotationally Grazed Pastures In Southwest Iowa, Ryan David Marquardt Jan 2008

Grassland Bird Abundance And Nesting In Short-Duration Rotationally Grazed Pastures In Southwest Iowa, Ryan David Marquardt

Retrospective Theses and Dissertations

Grassland bird populations across the Midwest are experiencing declines due to loss of habitat, which could potentially be replaced with grazing systems. This study measured abundance, nesting, and derived conservation values for a rotational stocking grazing management unit where cool-season grass (CSG) paddocks were grazing in the spring and fall and rested in the summer, and warm-season grass (WSG) paddocks were grazed in the summer and rested in spring an fall. Adjacent ungrazed Conservation Reserve Program lands in CSG and WSG served as control treatments. Dickcissels (Spiza americana ) had bird densities in ungrazed WSG fields (3.8+/-0.29 birds ...


Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha Jan 2008

Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha

Retrospective Theses and Dissertations

Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS ...


Comparison Of Esn, Urea, And Aqua Ammonia As Sources Of Nitrogen For Corn Production In Iowa, Jeffrey Allen Moore Jan 2008

Comparison Of Esn, Urea, And Aqua Ammonia As Sources Of Nitrogen For Corn Production In Iowa, Jeffrey Allen Moore

Retrospective Theses and Dissertations

Three nitrogen response studies were conducted in Iowa to compare the effect of a controlled release fertilizer, ESN, to urea and aqua ammonia (AA), on corn grain yields, biomass yields, and soil nitrate (NO3 --N) and ammonium (NH4+-N) concentrations. Experiments were conducted at two sites from 2003 through 2007 for the spring-applied ESN/urea study, two sites from 2006 through 2007 for the fall and spring-applied ESN/AA study, and one site from 2006 through 2007 for the spring applied ESN/AA study. N rates in the studies were 0-202 kg ha-1 in 34 kg N ha-1 increments in ...


Assessment Of Nitrogen Supply From Poultry Manure Applied To Corn, Dorivar A. Ruiz Diaz Suarez Jan 2007

Assessment Of Nitrogen Supply From Poultry Manure Applied To Corn, Dorivar A. Ruiz Diaz Suarez

Retrospective Theses and Dissertations

No abstract provided.


Predicting The Dispersion And Viability Of Maize Pollen, Brian J. Viner Jan 2007

Predicting The Dispersion And Viability Of Maize Pollen, Brian J. Viner

Retrospective Theses and Dissertations

No abstract provided.


Soil Respiration And Plant Growth Across A Chronosequence Of Tallgrass Prairie Reconstructions, Ryan Matthew Maher Jan 2007

Soil Respiration And Plant Growth Across A Chronosequence Of Tallgrass Prairie Reconstructions, Ryan Matthew Maher

Retrospective Theses and Dissertations

An understanding of changes in soil respiration (Rs) and plant growth in tallgrass prairies planted into formerly cultivated land is critical if we are to predict the effects of grassland reconstructions on belowground carbon cycling. In addition, predicting changes in the ecosystem carbon balance in grassland reconstructions will require identifying the climatic and biological controls on Rs across a landscape of cultivated and reconstructed grassland ecosystems. This study used a 12 yr chronosequence of tallgrass prairie reconstructions in central Iowa, including a no-till soybean field (age 0), to quantify the relationship between tallgrass prairie age, R s, root biomass, root ...


Land Management Database Development: Methods For Delineating Management Units And Estimating Crop And Residue Cover, Brian Keith Gelder Jan 2007

Land Management Database Development: Methods For Delineating Management Units And Estimating Crop And Residue Cover, Brian Keith Gelder

Retrospective Theses and Dissertations

The world's agricultural soil resources continue to degrade due to rates of soil erosion and organic matter oxidation exceeding those found in native systems. This degradation is generally the result of intensive soil tillage, resulting in decreased amounts of soil residue cover, high runoff rates, and decreased soil organic matter. Degradation pressure is likely to increase in the future due to harvesting of plant residues for bioenergy and increased peak intensity of rainstorms due to climate change, increasing soil detachment and transport.;Developing effective solutions to these problems require the use of models to estimate the extent and severity ...


Efficiency Of Fall And Spring Broadcast Fertilizer Phosphorus Application For Corn And Soybean In No-Till, Sebastián Raúl Barcos Jan 2007

Efficiency Of Fall And Spring Broadcast Fertilizer Phosphorus Application For Corn And Soybean In No-Till, Sebastián Raúl Barcos

Retrospective Theses and Dissertations

Previous Iowa research has shown consistent grain yield differences among broadcast, shallow band, and deep band P placement methods for no-till corn (Zea mays L.) and soybean (Glycine max [L.] Merr.). One reason for lack of differences between P placement methods in Iowa might be that broadcast P was always applied in the fall (4-5 months before planting). This study evaluated the efficiency of fall and spring broadcast P application for corn and soybean under no-till by conducting 20 trials on fields testing 6 to 29 mg kg-1 (Bray-P1, 15-cm depth). Triple superphosphate was broadcast at 0, 10, 20, 30 ...


Soil Management, Crop Rotations, And Biomass Removal Effects On Soil Organic Matter Content, Krisztina Eleki Jan 2007

Soil Management, Crop Rotations, And Biomass Removal Effects On Soil Organic Matter Content, Krisztina Eleki

Retrospective Theses and Dissertations

No abstract provided.


Using On-Farm Strip-Trials To Improve Nitrogen Management For Corn, Gaylia Clare Gries Ostermeier Jan 2007

Using On-Farm Strip-Trials To Improve Nitrogen Management For Corn, Gaylia Clare Gries Ostermeier

Retrospective Theses and Dissertations

No abstract provided.


Long Term Effects Of Phosphorus And Conservation Tillage Management On Crop Yield And Soil Phosphorus In Corn-Soybean Rotations, Jacob Prater Jan 2007

Long Term Effects Of Phosphorus And Conservation Tillage Management On Crop Yield And Soil Phosphorus In Corn-Soybean Rotations, Jacob Prater

Retrospective Theses and Dissertations

No abstract provided.


Environmental Fate And Chemistry Of A Veterinary Antibiotic-Tylosin And Monoterpenoid Pesticides-Thymol And Phenethyl Propionate, Dingfei Hu Jan 2007

Environmental Fate And Chemistry Of A Veterinary Antibiotic-Tylosin And Monoterpenoid Pesticides-Thymol And Phenethyl Propionate, Dingfei Hu

Retrospective Theses and Dissertations

With increasing utilization of various synthetic or natural chemicals, the adverse impact of these chemicals and their degradates is of a concern due to their presence in the environment. However, for most currently used synthetic chemicals, the fate of their degradates are yet to be elucidated. General processes and principles of environmental fate were described. These processes, chemical degradation, biodegradation and photodegradation, affect persistence, and other processes, such as binding, plant/animal uptake, volatilization, runoff, leaching, all influence the movement of a chemical and its degradates in the environment. All processes apply to both parent compounds and their following degradates ...


Diversifying Midwestern Agriculture With Perennial Forages: A Review Of The Benefits And Barriers To Forages In Iowa, And A Genetic Study Of Biofuel Potential For Reed Canarygrass, Julia Olmstead Jan 2007

Diversifying Midwestern Agriculture With Perennial Forages: A Review Of The Benefits And Barriers To Forages In Iowa, And A Genetic Study Of Biofuel Potential For Reed Canarygrass, Julia Olmstead

Retrospective Theses and Dissertations

This thesis addresses first the socio-political, economic, and ecological consequences and causes of decreased forage production in Iowa, and then focuses on a breeding study related to the biofuel potential of reed canarygrass. In the first paper I review the agronomic, ecological, and economic benefits of forage incorporation into corn and soybeans rotations and then attempt to explain the socio-political reasons why forages are not grown on more Iowa farms. The second paper details an evaluation of reed canarygrass germplasm for biofuel traits. We evaluated the entire reed canarygrass germplasm collection available in the US for biomass and quality traits ...


Dynamic Soil Properties Across A Suburban Landscape, Ankeny, Iowa, Amy Elizabeth Norton Jan 2007

Dynamic Soil Properties Across A Suburban Landscape, Ankeny, Iowa, Amy Elizabeth Norton

Retrospective Theses and Dissertations

Humans influence soil properties through agriculture, urbanization, and many other activities. This study investigated the degree to which humans influence dynamic soil properties (including bulk density, organic carbon, and heavy metal concentrations) in a suburban landscape and assesses the variability of these soil properties with respect to the length of time that has passed since disturbance or construction activities. Aerial photos were used to delineate residential areas from different years and nine time periods of development were established. Ten homes from each time period of development were randomly selected and soil samples were collected from the center of the front ...


Grazing Management Effects On Sediment And Phosphorus Losses From Streambanks, Shelly Lee Nellesen Jan 2007

Grazing Management Effects On Sediment And Phosphorus Losses From Streambanks, Shelly Lee Nellesen

Retrospective Theses and Dissertations

Agricultural lands are the leading cause of nonpoint-source pollution in the United States. Previous studies indicate that grazed lands can have more impact on sediment and phosphorus (P) losses to surface waters than cropland or other agricultural lands. The purpose of this research was to determine the effects of different grazing managements on streambank erosion and potential P losses. In 2004, three treatments, including rotational stocking, continuous stocking with limited stream access, and continuous stocking with full stream access were established in six adjacent pastures along Willow Creek at a research farm in Marshall County, Iowa. Erosion measurements were taken ...


Modeling Phosphorus Transport Using The Wepp Model, Mario Perez-Bidegain Jan 2007

Modeling Phosphorus Transport Using The Wepp Model, Mario Perez-Bidegain

Retrospective Theses and Dissertations

The Water Erosion Prediction Project (WEPP) model has been widely tested for its ability to predict soil erosion, runoff, and sediment delivery over a very wide range of conditions and scales for both hillslopes and watersheds. However, WEPP has not been used to estimate nutrient loss, in particular phosphorus losses. It is well known that most of the phosphorus transported from cropland is attached to sediment; consequently management practices that reduce erosion and sediment transport could reduce phosphorus losses. Management practices like vegetative filter strips, grass barriers, and multispecies riparian buffers have been proposed to reduce the transport of sediment ...


Measurement Of Coupled Soil Heat And Water Processes, Joshua L. Heitman Jan 2007

Measurement Of Coupled Soil Heat And Water Processes, Joshua L. Heitman

Retrospective Theses and Dissertations

Coupled soil heat and water processes are critical for terrestrial life at all scales. Yet detailed understanding of these processes is limited. Inability to measure fine-scale, transient, one-dimensional (1-D) heat and water redistribution encumbers laboratory and field experiments and restricts testing of theory. The impetus for this work is to strengthen understanding of soil heat and water processes through improved measurement. Objectives were to (1) Develop closed soil cells with 1-D, non-isothermal conditions; (2) Measure soil temperature, water content, and thermal conductivity distributions under transient, 1-D conditions; (3) Test diffusion-based coupled heat and water transfer theory; and 4) Measure in ...


Plumbing Agricultural Landscapes For Water Quality Improvement: Coexistence Of Intensive Agriculture And Good Water Quality, Zsolt Gemesi Jan 2007

Plumbing Agricultural Landscapes For Water Quality Improvement: Coexistence Of Intensive Agriculture And Good Water Quality, Zsolt Gemesi

Retrospective Theses and Dissertations

Years of data collection at the bases of 130 lake watersheds in Iowa have enabled us to study the relationships between nutrient concentrations and land use/land cover, as well as to measure the fluxes of key nutrients through hydrologically-linked agroecosystems within the landscape. These ecosystems are dominated by cropland and intensively managed fields with high nutrient export coefficients. Satellite image-derived land cover maps, digital elevation maps and soil mapping units were interpreted and manipulated using geographic information software. We evaluated the relationships between landscape characteristics and lake water quality in Iowa (USA) by regressing four lake water quality responses ...


Evaluation Of Potassium Soil Tests And Methods For Mapping Soil Fertility Properties In Iowa Corn And Soybean Fields , Pedro Aníbal Barbagelata Jan 2006

Evaluation Of Potassium Soil Tests And Methods For Mapping Soil Fertility Properties In Iowa Corn And Soybean Fields , Pedro Aníbal Barbagelata

Retrospective Theses and Dissertations

Improving the use of soil testing in production agriculture may result in increased nutrient use efficiency and profitability. Three studies were conducted in Iowa with this general goal. One study assessed the impact of soil sample drying on K extraction and developed field correlations of an ammonium-acetate K test (AA) based on field-moist samples for corn and soybean. Potassium extracted with AA from dried samples was higher than K extracted from moist samples. The difference increased with increasing drying temperature, was inversely related to the soil K level, and varied among soil series. The moist AA test correlated better with ...


Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez Jan 2006

Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez

Retrospective Theses and Dissertations

Soybean grain contains isoflavones that may prevent various human diseases. Previous studies in Canada found that K fertilization and high grain K concentration can result in increased isoflavones concentration in grain, but effects were inconsistent across sites and soil-test K (STK) levels. The objective of this study was to assess (1) effects of K fertilization on the concentration of isoflavones and K in soybean grain and (2) relationships between soybean grains K concentration, isoflavone concentration, and yield. The study was based on analyses of grain collected from selected treatments and years of six Iowa long-term experiments that investigated effects of ...


Soil Quality Response To Manure Or Compost Amendments In Alternative Iowa Farm Systems , Kevin Frederick Jensen Jan 2006

Soil Quality Response To Manure Or Compost Amendments In Alternative Iowa Farm Systems , Kevin Frederick Jensen

Retrospective Theses and Dissertations

This study was conducted to improve understanding of carbon (C) and nitrogen (N) cycling in alternative agricultural systems. In order to generate information that is directly applicable to farm contexts, the study was conducted in farmer fields. The focus of this study was the soil phase of the C and N cycle, where physical and biological processes transform C and N. However, the design of the study, featuring on-farm research in partnership with farmers, ensured that soil and plant performance factors were integrated with the practical logistics and judgment calls that are exercised by farmers.


Reconstructing Quaternary Landscapes And Hydrology From Soil Survey Maps, Bradley A. Miller Jan 2006

Reconstructing Quaternary Landscapes And Hydrology From Soil Survey Maps, Bradley A. Miller

Retrospective Theses and Dissertations

This study was done to investigate the pre-settlement condition of the southern Des Moines Lobe landscape, with particular interest in the hydrological function of depressional wetlands. Soil survey maps were used to identify the soil formation environment from soil properties observed today. Understanding the factors of soil formation and geomorphology allows historical reconstructions of the landscape, hydrology, wildlife habitat, and potentially other areas of interest. This study interpreted and managed soil survey data to efficiently create a Quaternary geologic map, identify the extents of historical depressional wetlands, deduce information about the water budget of these wetlands, and estimate the region ...


Effects Of Crop Rotation And Nitrogen Fertilization On Soil Nitrate Concentration And Corn Yield , Enrique Ortiz-Torres Jan 2006

Effects Of Crop Rotation And Nitrogen Fertilization On Soil Nitrate Concentration And Corn Yield , Enrique Ortiz-Torres

Retrospective Theses and Dissertations

Increasing concerns about production cost and environmental impacts of N fertilization require improving N management. The objectives of this study were to evaluate effects of cropping sequences and N fertilization on (1) corn yield and yield stability and (2) soil nitrate concentration in two Iowa long-term rotation experiments and (3) to assess the performance of the late spring nitrate test (LSNT) to assess N availability for corn in several cropping sequences. The experiments were near Kanawha (20 yrs) and Nashua (26 yrs) and N fertilization rates for corn were 0, 90, 180, 270 kg N ha -1. Rotations in Kanawha ...


Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska Jan 2006

Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska

Retrospective Theses and Dissertations

Iron deficiency chlorosis (IDC) and soybean cyst nematode (SCN; Heterodera glycines) infestation are major factors that contribute to soybean (Glycine max Merr.) yield reduction in the Midwest. The IDC is often associated with soybean grown on high pH, calcareous soils. In addition, it was documented that SCN population density is higher in high pH soils. The objectives of this paper were to assess the proportion of within-field soybean yield and SCN variability that could be explained by soil pH, calcium carbonate equivalent (CCE), and a previously defined alkalinity stress index (ASI). Aerial images from 21 fields planted to SCN-resistant or ...