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Full-Text Articles in Life Sciences

Breeding Birds Of A Large-Scale Tallgrass Prairie Restoration In Iowa: Monitoring Abundance And Frequency Of Occurrence, Liessa Hyde Thomas Jan 1999

Breeding Birds Of A Large-Scale Tallgrass Prairie Restoration In Iowa: Monitoring Abundance And Frequency Of Occurrence, Liessa Hyde Thomas

Retrospective Theses and Dissertations

Little is known about avian response to habitat restoration, particularly for tallgrass prairies. Neal Smith National Wildlife Refuge, established in 1990, is one of the largest tallgrass prairie restorations of its kind, with land acquisition approved at 3504 ha. Point count surveys were conducted at Neal Smith National Wildlife Refuge from mid May through mid July, 1994-1998. Randomly selected points from four vegetation classes: cropland, herbaceous, riparian, and woodland, were surveyed over the five year study period. A total of 91 summer resident bird species were detected, including 8 grassland-specific species and 2 species from the Iowa threatened species list ...


Human Impacts On Soils And Geomorphic Processes On The Des Moines Lobe, Iowa , Michael E. Konen Jan 1999

Human Impacts On Soils And Geomorphic Processes On The Des Moines Lobe, Iowa , Michael E. Konen

Retrospective Theses and Dissertations

A watershed scale approach to examining post-European settlement erosion-sedimentation was undertaken on the Des Moines Lobe in northcentral Iowa. Two closed basins comprised of glacigenic diamicton were selected for detailed field examination. The objectives of the study were to quantify post-settlement erosion-sedimentation rates and to characterize post-settlement hillslope sediments (PSHS) and the underlying buried soils. Soil morphology, particle-size distribution, mass magnetic susceptibility measurements, organic carbon depth distributions, quantitative soil color measurements, and cesium-137 depth distributions were utilized to identify PSHS and quantify erosion-sedimentation rates. Maximum thicknesses of 100 and 93 cm of PSHS were described in the two basins. Average ...


Herbicide And Conservative Tracer Movement Through The Soil Profile And To Subsurface Drains Under No-Till And Chisel Plow Systems , Syed Imran Ahmed Jan 1999

Herbicide And Conservative Tracer Movement Through The Soil Profile And To Subsurface Drains Under No-Till And Chisel Plow Systems , Syed Imran Ahmed

Retrospective Theses and Dissertations

Adoption of conservation tillage has increased the role of macropore flow on the transport of agricultural chemicals to groundwater. Therefore, it is important to understand the role of macropore flow in the transport of water through the vadose zone and to the shallow groundwater. Two field studies were conducted at Iowa State University's Agricultural Research Center near Boone, Iowa, to determine the effect of two tillage practices (chisel plow and no-till) on the transport of herbicides and tracers, with applied water, through the soil profile and to the shallow groundwater. Two herbicides, atrazine [(6-chloro-N-ethyl-N-(1-methylethyl-1,3,5 triazine)-2-4-diamine ...


Effect Of Soil Ph On Phytoavailability Of Nitrogen In Biotechnology By-Products And Animal Manures , Fahad Mohamad Alromian Jan 1999

Effect Of Soil Ph On Phytoavailability Of Nitrogen In Biotechnology By-Products And Animal Manures , Fahad Mohamad Alromian

Retrospective Theses and Dissertations

Biotechnology by-products and animal manures have received considerable attention in recent years because of the problems associated with their disposal and because of their potential use as soil amendments and as sources of nutrients for crops. A laboratory experiment was conducted to assess the potential N mineralization in five biotechnology by-products and three animal manures added to an agricultural soil with pH values of 5, 6, and 7 and incubated at 20°C or 30°C. Two greenhouse experiments were conducted by using the same soils to evaluate those materials as sources of N for plants; corn (Zea mays L ...


Spatio-Temporal Modeling In An Agricultural Watershed , Shabana Hameed Jan 1999

Spatio-Temporal Modeling In An Agricultural Watershed , Shabana Hameed

Retrospective Theses and Dissertations

Non-point source pollution in agricultural regions in the Midwest consists of two important components, namely, dislodgment of common pollutants, their movement across the landscape and subsequently transport through surface waters to their final destination. The objectives of this study were to: 1) model surface movement of agricultural pollutants for a succession of sub-watersheds in Bear Creek using AGNPS; 2) calibrate and validate the model for a small sub-watershed using available experimental plot data; 3) incorporate Monte Carlo simulation within the modeling process where field data was not available; 4) apply the calibrated and validated model to a small sub-watershed with ...


Winter Survival And Population Dynamics Of Bean Leaf Beetle (Coleoptera: Chrysomelidae) , Wai-Ki Frankie Lam Jan 1999

Winter Survival And Population Dynamics Of Bean Leaf Beetle (Coleoptera: Chrysomelidae) , Wai-Ki Frankie Lam

Retrospective Theses and Dissertations

Ecological study of the population dynamics of bean leaf beetle adults, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), with special reference to the overwintering populations, was conducted in central Iowa. Ecological habits, spatial distribution, cold tolerance, and winter survival of overwintering beetle adults, were studied for 3-yr (1996 through 1999). Additionally, the population fluctuation of the adult beetles during the growing season was studied for 10-yr, from 1989 through 1998, inclusively. Overwintering beetle adults mostly hibernated in the crop residue of soybean fields ( ≈ 20%) and leaf litter of woodlands ( ≈ 80%). A few beetles (< 1%) overwintered in alfalfa fields, cornfields, and grasslands. The overwintering adults aggregated in the litter of soybean fields and woodlands. Residue in the habitats served as an insulating layer for the overwintering beetles. However, over 50% mortality of the overwintering beetles was observed in both soybean fields and woodlands during the 3-yr study. Laboratory study indicated that most of the overwintering beetles survived more than hundreds of hours when they were kept at --5°C or above, whereas most of the beetles died when they were kept at --10°C or below. This result indicated that cold temperature has a strong effect on the winter survival of the overwintering populations. A model for the estimation of the mortality of overwintering beetle adults, based on the accumulation of the air mean subfreezing winter temperature, was developed. Linear regression and multiple regression stepwise selection procedure analyses were used to relate environmental factors to population fluctuations of bean leaf beetle during the 10-yr study. The analyses showed a strong relationship between the environmental factors, including temperature and precipitation, and beetle population densities. A predictive model for F2 adults in the next late season was developed. The major factors affecting the survival of overwintering populations and population fluctuations of the beetles, estimation of winter survival, and the prediction of the population dynamics of bean leaf beetle during seasonal cycles are discussed.


Characterization Of Preferential Solute Transport In Soil , Jaehoon Lee Jan 1999

Characterization Of Preferential Solute Transport In Soil , Jaehoon Lee

Retrospective Theses and Dissertations

The occurrence of preferential flow for rapid movement of solute through soil has been reported. However, there are not many practical methods to detect, quantify, and identify preferential flow. The characterization of preferential flow would improve our understanding of field water and solute behavior. A concept that separates water content into "mobile" and "immobile" domain has been successful in describing some forms of preferential solute transport. The mobile-immobile model (MIM) has three significant parameters- immobile water content (thetaim), mass exchange coefficient (alpha), and dispersion coefficient (D m). Although one can determine these parameters by applying inverse methods to effluent breakthrough ...


Weeds/Weed Seedbank And Soil Fungi Responses To Tillage And Cropping Systems , Joel Felix Jan 1999

Weeds/Weed Seedbank And Soil Fungi Responses To Tillage And Cropping Systems , Joel Felix

Retrospective Theses and Dissertations

A four year field experiment was conducted from 1994 through 1997 to elucidate the effects of tillage, cropping systems, and weed management regimes on land previously under the conservation reserve program (CRP). A total of 13 weed species comprised the weed seedbank which was dominated by broadleaf weeds. The seedbank for common lambsquarters and Amaranthus species were 10,365 and 31,925 seeds M-2 in the first year out of CRP, respectively. The Amaranthus species seedbank continued to increase and climaxed at 51,670 seeds M-2 in 1996. The seedbank for Setaria species increased 19 fold between 1994 and 1997 ...


The Use Of Anuran Larvae To Determine Chronic And Acute Toxicological Effects From Exposure To Atrazine And Metolachlor , Linda Suzanne Gucciardo Jan 1999

The Use Of Anuran Larvae To Determine Chronic And Acute Toxicological Effects From Exposure To Atrazine And Metolachlor , Linda Suzanne Gucciardo

Retrospective Theses and Dissertations

This research investigated the effects of chronic exposure of amphibian tadpoles and acute exposure of embryos to the agricultural chemical atrazine;Tadpoles were chronically exposed from the first feeding stage through metamorphosis to three levels of atrazine. Concentrations of 30, 300 and 600 mug/L reflect exposures likely to occur in streams, wetlands and temporary waters near croplands. Cricket frogs (Acris crepitans), wood frogs (Rana sylvatica) and northern leopard frogs (R. pipiens ) were evaluated on rate of growth, days to metamorphosis, metamorphic success, and juvenile weight and length. A repeated measures ANOVA evaluated the rate of growth (increase in SVL ...


Local Dependency: The Independent Farmer Myth , Eric Bruce Imerman Jan 1999

Local Dependency: The Independent Farmer Myth , Eric Bruce Imerman

Retrospective Theses and Dissertations

The purpose of this dissertation is to achieve a higher level of understanding of the adoption and diffusion process of conservation technology on Iowa farms. The tools used in this discovery process are a qualitative analysis of farmers' perceptions of conservation technologies, an analysis of the adoption and diffusion model, and the formulation of a local dependency theory to explain the patterns of adoption on Iowa farms. Specifically, this investigation comes to the conclusion that the Iowa farmer is trapped in a dependency situation that is controlled by the government, trans-national corporations, and local capital, a triad known as the ...


Experimental Investigation Of The Removal Of Hydrophobic Organic Compounds From Two Iowa Soils Using Food Grade Surfactants And Recovery Of Used Surfactants , Dal-Heui Lee Jan 1999

Experimental Investigation Of The Removal Of Hydrophobic Organic Compounds From Two Iowa Soils Using Food Grade Surfactants And Recovery Of Used Surfactants , Dal-Heui Lee

Retrospective Theses and Dissertations

The ability of food grade aqueous surfactant solutions to remove toluene or 1,2,4-trichlorobenzene entrapped in sand and two Iowa soils was evaluated in batch and column experiments. Also, the effects that environmental conditions have on contaminant solubilization and mobilization by surfactants and the technical viability of recovering the surfactants for possible reuse were studied;Synergism between the anionic Dowfax 8390 and the nonionic T-Maz 60 was not observed. A mixture of the two was less effective than Dowfax 8390 by itself. 1,2,4-trichlorobenzene removal enhancements via microemulsifiers were less effective than that by Dowfax 8390 for a ...


Economic Analysis Of Pesticide Regulation In The U.S. Apple Industry , Jutta Roosen Jan 1999

Economic Analysis Of Pesticide Regulation In The U.S. Apple Industry , Jutta Roosen

Retrospective Theses and Dissertations

Several particularities of apple production systems require careful consideration of the methods used to estimate impacts of pesticide regulation. Growing conditions are geographically diverse, quality considerations are of particular importance, and dynamic aspects need to be acknowledged in production systems of perennial crops;A partial-equilibrium model of the apple industry is estimated where orchards are modeled as multiproduct firms producing apples for fresh and processed consumption. Groups of growers are distinguished by region and by pesticide use patterns. The changes of quantities and prices in the markets for fresh and processed apples that follow a technology shift are derived. Economic ...


Dynamics Of Biosolids-Derived Phosphorus In A Mollisol , Yaobing Sui Jan 1999

Dynamics Of Biosolids-Derived Phosphorus In A Mollisol , Yaobing Sui

Retrospective Theses and Dissertations

Land application of biosolids (treated municipal sewage sludge) is becoming more popular because it is an agronomically, environmentally, and economically acceptable means for biosolids disposal. When the amount of biosolids is applied to agricultural land according to N-based on agronomic rate, however, the amount of P applied is generally more than plants need. The subsequent accumulation of P is of environmental concern, because it could lead to eutrophication of water bodies if P is carried off-site in runoff water and eroded soils. Thus, a completely randomized block experiment with three biosolids treatments (control, low, and high biosolids application rates) and ...


Statistical Methods For Count Data From Designs With Nested Structure , Ling-Ling Claire Tsao Jan 1999

Statistical Methods For Count Data From Designs With Nested Structure , Ling-Ling Claire Tsao

Retrospective Theses and Dissertations

Count data from nested designs, split-plot experiments, and repeated measures studies are commonly encountered in agricultural and ecological research. Such data are often analyzed using analysis of variance methods based on distributional assumptions that may not be valid for count data, especially when expected counts are small. Furthermore, inferences for generalized linear models, such as log-linear and logistic regression models, are generally based on an assumption of independent Poisson or binomial counts that does not adequately account for correlations and heterogeneity arising in count data from nested designs. Recent developments for generalized linear mixed models, quasi-likelihood estimation and robust covariance ...


Effects Of Variable Rates, Times And Methods Of Application Of Swine Manure On Nitrate-Nitrogen In Subsoil Water, Crop Yields, N Uptake And Recovery And Soil Residual Nitrate-Nitrogen: A Three Year Study , Sara Dominga Smith Jan 1999

Effects Of Variable Rates, Times And Methods Of Application Of Swine Manure On Nitrate-Nitrogen In Subsoil Water, Crop Yields, N Uptake And Recovery And Soil Residual Nitrate-Nitrogen: A Three Year Study , Sara Dominga Smith

Retrospective Theses and Dissertations

Land application of swine manure offers the alternative use of its nutrients for crop production but growing concerns exist when not properly managed because of potential water quality problems;The field experiment consisted of 48 plots (15.24 x 3.04 m), located in a Clarion-Nicollet-Webster soil association. Corn (Zea mays L.) was rotated with soybean (Glycine max L.). Treatments applied were a factorial combination of Nitrogen (N) rates (0, 84, 168 and 252 kg-N/ha) of liquid swine manure and Urea-Ammonium-Nitrate (UAN) with methods of application (manure in spring, fall and side-dress; manure with nitrapyrin in fall and UAN ...


Effectiveness Of A Multi-Species Riparian Buffer System For Sediment And Nutrient Removal , Kye-Han Lee Jan 1999

Effectiveness Of A Multi-Species Riparian Buffer System For Sediment And Nutrient Removal , Kye-Han Lee

Retrospective Theses and Dissertations

Nonpoint source (NPS) pollution from agricultural areas is one of the most critical problems threatening the nation's water resources. Surface runoff is a major carrier of NPS pollutants. Riparian buffers have been proposed as a means of reducing transport of NPS pollutants from agricultural areas to streams. Using rainfall simulation techniques and natural runoff monitoring, plot studies were conducted to evaluate the ability of an established multi-species riparian buffer system to reduce sediment and nutrient in agricultural runoff. The buffer system evaluated contained three types of vegetation: cool-season grasses, warm-season grasses, and woody plants. Results indicated that the effectiveness ...


Use Of Site Specific Farming Systems And Computer Simulation Models For Agricultural Productivity And Environmental Quality , Allah Bakhsh Jan 1999

Use Of Site Specific Farming Systems And Computer Simulation Models For Agricultural Productivity And Environmental Quality , Allah Bakhsh

Retrospective Theses and Dissertations

Site specific farming systems have the potential to increase farmers' net income by reducing the use of agro-chemicals and applying variable rate technology for areas showing stable yield patterns. This study was designed to: (1) study yield patterns in given fields using variography; (2) seek correlation among soil attributes and yield data using GIS; and (3) simulate the effects of N-fertilizer and swine manure application rates on NO 3-N losses with subsurface drainage water and crop yields. The results of this study showed that the spatial correlation lengths were found to vary from 40 m for corn to about 90 ...


A Decision Support System For Planning And Management Of Sustainable Livestock Production In The Midwest, Irene Mary Crawford Jan 1999

A Decision Support System For Planning And Management Of Sustainable Livestock Production In The Midwest, Irene Mary Crawford

Retrospective Theses and Dissertations

Managing livestock operations in an environmentally sound way presents a major challenge to the livestock production industry. Excessive amounts of manure can cause major environmental problems if not properly managed. The contamination of surface and subsurface water supplies due to non-point source pollution from livestock production has increased public concern in regards to large livestock operations. Another source of pollution from livestock facilities is atmospheric pollution in the form of odor. Odorous gaseous, such as carbon dioxide, methane, ammonia, and other gaseous from livestock operations are a health hazard and nuisance to neighboring populations. Analysis of the environmental impacts of ...