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Articles 1 - 14 of 14

Full-Text Articles in Life Sciences

Corn Yield Response To Rotation Effect, N Fertilizer Application And Row Position In A Strip Intercropping System, Urszula Choromanska Jan 1995

Corn Yield Response To Rotation Effect, N Fertilizer Application And Row Position In A Strip Intercropping System, Urszula Choromanska

Retrospective Theses and Dissertations

No abstract provided.


Fish Communities In Small Agricultural Streams Of Iowa: Relationships With Environmental Factors , Shih-Hsiung Liang Jan 1995

Fish Communities In Small Agricultural Streams Of Iowa: Relationships With Environmental Factors , Shih-Hsiung Liang

Retrospective Theses and Dissertations

Fish distribution and composition in small agricultural streams were compared between major river basins (Mississippi and Missouri) and among five subecoregions in the Iowa region of the Western Corn Belt Plains Ecoregion (WCBPE)) using a 1981-1984 state survey database. Additionally, environmental and fish data were collected from April 1992 to October 1993 from five 50-m stream sections in each of 10 streams representing the subecoregions. The associations among watershed, stream habitat, and fish community features were investigated. The 1993 flooding effects on the headwater habitat and fish communities were also explored. Watershed data were derived from maps, remote imagery and ...


Behavior Of Larval Walleye , Phillip Warren Rieger Jan 1995

Behavior Of Larval Walleye , Phillip Warren Rieger

Retrospective Theses and Dissertations

High resolution cinematography was used to observe larval walleye (Stizostedion vitreum) behavior in laboratory aquaria. Observations focused on gas bladder inflation (GBI), first-feeding, and cannibalism. Four discrete phases of developmental behavior were observed: surface suspension (from hatch to 40 TU); a GBI phase (40-100 TU) with constant, rapid anquilliform swimming at the water surface; a first-feeding phase (100-240 TU) with slower, more subcarangiform swimming throughout the water column in search of food; and, a fully exogenous phase (after 240 TU) when the larvae move to the bottom of culture tanks and easily consume sinking feed particles that come within close ...


A Natural Area Inventory Of Ames, Iowa , William Russell Norris Jan 1995

A Natural Area Inventory Of Ames, Iowa , William Russell Norris

Retrospective Theses and Dissertations

Perhaps no state in the Union has suffered such widespread degradation of its natural vegetation as Iowa. Tallgrass prairie (including wet prairie communities, often considered to be wetlands) once covered at least 85% of this state's land area, but more than 99.9% of Iowa's original grasslands have fallen victim to the plow (Smith 1990). Wetlands once covered 11.1% of Iowa's landscape (Dahl 1990), but virtually all of these have been drained to make way for rowcrops (wetlands now cover only 1.2% of Iowa's landscape). Roughly 12 to 20% of the state was covered ...


Amino Acid Composition Of Soil Organic Matter And Nitrogen Transformations In Soils Under Different Management Systems , Zachary Ngewoh Senwo Jan 1995

Amino Acid Composition Of Soil Organic Matter And Nitrogen Transformations In Soils Under Different Management Systems , Zachary Ngewoh Senwo

Retrospective Theses and Dissertations

Studies of amino acid composition of soil organic matter extracted from 10 Iowa surface soils and from surface soils of two long-term rotation experiments showed that, with the exception of asparagine plus aspartic acid and glutamine plus glutamic acid, the other 13 amino acids, expressed as percentages of total amino acid extracted, were very uniform among the soils. The total amino acid extracted was significantly correlated with organic C (r = 0.79[superscript]\*\*) and clay content (r = 0.76[superscript]\*\*), but not with total N. Expressed as percentages of organic C and N in soils, the amounts extracted ranged from ...


Measuring And Modeling Alachlor Dissipation In Soil , Dee Anna Jo Weed Jan 1995

Measuring And Modeling Alachlor Dissipation In Soil , Dee Anna Jo Weed

Retrospective Theses and Dissertations

Field and laboratory experiments evaluated the overall dissipation of alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide) and the effect of no-till and chisel-plow tillages on alachlor leaching and dissipation. In the top 30-cm layer of field soil, the time to 50% dissipation (half-life) was 2 to 3 d, and the time to 90% dissipation ranged from 17 to 30 d. In no-till soil, alachlor dissipated slightly faster, and more was transported into the 10-to-30-cm soil layer. The tillage effect depended on weather that favored movement into and dissipation within the soil, rather than dissipation on plant residues and the soil ...


"A Green And Permanent Land": Agriculture In The Age Of Ecology, 1935-1985 , Randal Scott Beeman Jan 1995

"A Green And Permanent Land": Agriculture In The Age Of Ecology, 1935-1985 , Randal Scott Beeman

Retrospective Theses and Dissertations

This is an intellectual history that traces the influence of ecological thought on the theory, practice, and policy of agriculture in the United States since the 1930s. Ecology served as both a scientific and ethical guide for two broad social movements analyzed in this dissertation. The "permanent agriculture" movement of the 1930s through the 1950s emerged from concerns over the destruction of the soil, and the desire to harmonize human technological endeavors with the interconnected biological and social universes in which humans functioned. Champions of permanent agriculture effectively promoted an ideology devoted to long-term land use planning, comprehensive soil conservation ...


Territorial Behavior Of The Red Admiral Butterfly, Vanessa Atalanta (L.) (Lepidoptera: Nymphalidae) , Royce Justin Bitzer Jan 1995

Territorial Behavior Of The Red Admiral Butterfly, Vanessa Atalanta (L.) (Lepidoptera: Nymphalidae) , Royce Justin Bitzer

Retrospective Theses and Dissertations

This study of territorial behavior in the nymphalid butterfly Vanessa atalanta examines a number of behavioral and climatic factors shaping how, when, and for how long males maintain territories during the late afternoons of late spring and summer. Territorial V. atalanta males were observed on the Iowa State University campus from early April/early May to late August/early September from 1987 to 1992 on a total of 224 days. Microclimatic conditions were simultaneously recorded with automatic datalogging equipment. Males started territorial activity later on warmer days and when the ground was cooler, under all types of cloud cover. Although ...


Pasture Soils In The Tropical Moist Life Zone Of Costa Rica: Implications For Secondary Forest Succession , James Weeks Rosacker Jan 1995

Pasture Soils In The Tropical Moist Life Zone Of Costa Rica: Implications For Secondary Forest Succession , James Weeks Rosacker

Retrospective Theses and Dissertations

A study was conducted in the Tropical Moist Forest Premontane Life Zone in the Puriscal area of Costa Rica to examine differences in soil characteristics in the upper 15 cm of twenty-four paired plots of undisturbed primary forest and pasture. Bulk density and pH were different between the forest and pasture plots. Clay content, total organic carbon and total nitrogen were not different. The twenty-four pasture plots were divided into three erosion groups. There were differences in clay content, organic carbon and total nitrogen between the groups. Clay content of the pasture plots increased with increased erosion, while organic carbon ...


A Spatial Decision Support System For The Analysis Of Environmental Impacts Of Integrated Crop-Livestock Production System , Dharmesh Kumar Jain Jan 1995

A Spatial Decision Support System For The Analysis Of Environmental Impacts Of Integrated Crop-Livestock Production System , Dharmesh Kumar Jain

Retrospective Theses and Dissertations

Recent shifts toward intensive and large confined livestock production units to enhance economic growth coupled with increased concerns for air, soil, and water quality have necessitated the development of computer-based management decision support systems for selecting environmentally sound production sites and for planning sustainable production systems. This dissertation describes the development and application of an interactive spatial decision support system that integrates a geographic information system, spatial and biophysical modeling, and a knowledge-based system into an interactive tool to facilitate planning and management of environmentally-sound livestock production. The spatial decision support can be used to select suitable watershed land areas ...


Line Narrowing Spectroscopic Studies Of Dna-Carcinogen Adducts And Dna-Dye Complexes , Myungkoo Suh Jan 1995

Line Narrowing Spectroscopic Studies Of Dna-Carcinogen Adducts And Dna-Dye Complexes , Myungkoo Suh

Retrospective Theses and Dissertations

Laser-induced fluorescence line narrowing (FLN) and non-line narrowing (NLN) spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7[beta],8[alpha]-dihydoxy-9[alpha],10[alpha]-epoxy-7,8,9, 10-tetrahydrobenzo (a) pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, (-)-trans-, (+)-cis- and (-)-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in the oligonucleotide, 5'-d(CCATCGCTACC) ยท (GGTAGCGATGG), exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction (~25%) exists in a partially base-stacked conformation. Both cis adducts were found to be ...


Degradation Of Chlorpyrifos In Soil: Effect Of Concentration, Soil Moisture, And Temperature , James Henry Cink Jan 1995

Degradation Of Chlorpyrifos In Soil: Effect Of Concentration, Soil Moisture, And Temperature , James Henry Cink

Retrospective Theses and Dissertations

The dissipation of the organophosphorus insecticide chlorpyrifos was investigated in field and laboratory samples. Six field locations were selected within the United States, and included the states of Arizona, Florida, Hawaii, Iowa, Mississippi, and Texas. Five of the six locations were selected based on their suspected aggressive degradative capabilities towards this chemical;In the field study, chlorpyrifos was applied to surficial trenches prepared on the north and south side of each building and parallel to the foundation. In the soil samples from Florida, Hawaii, and Texas, concentrations decreased by more than 50% of the initial concentration within 3 mo of ...


Development Of An Iowa Planning Model For The State Wetland And Riparian Area Plan, Jeffrey R. Logsdon Jan 1995

Development Of An Iowa Planning Model For The State Wetland And Riparian Area Plan, Jeffrey R. Logsdon

Retrospective Theses and Dissertations

No abstract provided.


Microbial Biodegradation Of The Herbicide 2,4-D In Soils And Subsurface Sediments, Jennifer Anne Welch Jan 1995

Microbial Biodegradation Of The Herbicide 2,4-D In Soils And Subsurface Sediments, Jennifer Anne Welch

Retrospective Theses and Dissertations

Widespread usage and detection of agricultural chemicals in surface and ground water systems has prompted many researchers to monitor their fate in the environment. Despite the potentially important role of microorganisms in the biodegradation process, microbial responses to agricultural chemicals are largely unknown. Our investigations were an effort to determine the innate ability of surface soils and subsurface sediments to attenuate agricultural chemicals prior to chemical migration into aquifers. The objectives of our studies were to investigate microbial degradation potential of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D} and to determine baseline microbial populations and activities in surface and shallow ...