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Articles 1 - 12 of 12

Full-Text Articles in Engineering

Crop And Tillage Management Effects On Water Flow And Nitrate-Nitrogen Loss Through Subsurface Drains , David L. Bjorneberg Jan 1995

Crop And Tillage Management Effects On Water Flow And Nitrate-Nitrogen Loss Through Subsurface Drains , David L. Bjorneberg

Retrospective Theses and Dissertations

Data were collected from subsurface drains on 36, 0.4-ha plots at Iowa State University's Northeast Research Farm near Nashua, IA to determine crop and tillage management effects on water flow and nitrate-N loss through subsurface drains. From 1990 to 1992, four tillage systems (chisel plow, moldboard plow, ridge till and no-till) were used with two crop rotations (continuous corn (Zea mays L.) and corn-soybean (Glycine max L. (Herr.)) rotation) and a single-spring fertilizer application. From 1993 to 1995, tillage systems were reduced to chisel plow and no-till, while fertilizer management changed to include single-spring fertilizer, spring-summer split fertilizer ...


Effects Of Shallow Water Tables On Soil Aeration, Water Quality, And Physiological Growth Of Soybean , Tahir Sarwar Jan 1995

Effects Of Shallow Water Tables On Soil Aeration, Water Quality, And Physiological Growth Of Soybean , Tahir Sarwar

Retrospective Theses and Dissertations

This study was conducted to investigate the effects shallow water table depths on soil aeration, groundwater quality and on some physiological growth and yield parameters of soybean. The experiments were conducted in two environmentally controlled growth chambers using sixteen lysimeters. Water table (WT) treatments were established on 37 day after planting (DAP), at depths of 0.15-, 0.30-, 0.45- and 0.60-m below the soil surface. Soil aeration status was determined by measuring soil oxygen concentrations at 0.15-, 0.30-, 0.60-m depths in the lysimeters. Effects of water table depths on groundwater quality were determined by ...


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 ...


Knowledge And Decision Support For Variable Rate Application Of Materials In Prescription Farming , Jack Robert Ambuel Jan 1995

Knowledge And Decision Support For Variable Rate Application Of Materials In Prescription Farming , Jack Robert Ambuel

Retrospective Theses and Dissertations

One major goal of prescription farming is to optimize application rates for seed fertilizer, and other agricultural inputs as a function of location within a field. There are four main components of a variable rate application system: (1) A method of determining the location of farm equipment (e.g. combines, tractors) within a field. (2) A system for controlling the application rate of materials (seeds, fertilizers, pesticides). (3) The capability to measure the results using a real time yield monitor. (4) An algorithm or prescription for determining what rates of materials to apply at each location. In this dissertation it ...


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 ...


Crassostrea Virginica On Constructed Intertidal Oyster Reefs: The Effects Of Tidal Height And Substrate Level On Settlement, Growth, And Mortality, Ian K. Bartol Jan 1995

Crassostrea Virginica On Constructed Intertidal Oyster Reefs: The Effects Of Tidal Height And Substrate Level On Settlement, Growth, And Mortality, Ian K. Bartol

Dissertations, Theses, and Masters Projects

No abstract provided.


Study Of The Time Efficiency And Volume Of Wood Used For Three Types Of Stove In The Salitrón Community Of San Juan Ermita, Department Of Chiquimula, Fredy Samuel Coronado López Jan 1995

Study Of The Time Efficiency And Volume Of Wood Used For Three Types Of Stove In The Salitrón Community Of San Juan Ermita, Department Of Chiquimula, Fredy Samuel Coronado López

Theses and Dissertations

In developing countries such as Guatemala, firewood is increasingly being used for cooking in most rural areas. Consequently, there is a shortage of firewood in these areas beca use trees do not grow at the same rate as they are consumed. Some authors report that 90% of the heat from firewood is lost during combustion. Several alternatives to open pit fires exist to reduce the amount of firewood used. However, these alternatives need to be evaluated to determine their efficiency. This project compared the time efficiency and volume of firewood used in the Finlandia style improved stoves, Josefina stoves, and ...


Air Cleaning Systems For Livestock Buildings , Atta Elmanan Mustafa Atia Jan 1995

Air Cleaning Systems For Livestock Buildings , Atta Elmanan Mustafa Atia

Retrospective Theses and Dissertations

The objective of this study was to design an ionization system for maximum collection efficiency. The laboratory studies were conducted to test the system and evaluate the performance of the prototypes. Two ionization systems were designed and tested in an air quality laboratory chamber. In the first system a high voltage negative ionization electrode and a neutral collector were used to charge and collect the dust from the air. Samples were obtained with the systems on and off. Samples were also obtained to compare the effectiveness of the second ionization system and an ionization system manufactured by Alpine. Two methods ...


Computer Simulation Of Coronary Blood Flow , Brian Christopher Frake Jan 1995

Computer Simulation Of Coronary Blood Flow , Brian Christopher Frake

Retrospective Theses and Dissertations

A computer model to simulate coronary fluid dynamics has been developed which can give some insight into the role of hemodynamics in health and disease. Although this study focuses mainly on coronary blood flow, the complete model consists of all major branches of the systemic circulation as well as the left epicardial coronary circulation;The flow equations are obtained by integrating the one-dimensional continuity and momentum equations over the cross-section of the artery to give a relationship between the primary variables of interest, the pressure and flowrate. An arctangent model was used as a constitutive equation to describe the pressure-area ...


Seed Furrow Sidewall Smearing By Double Disk Openers , Muhammad Iqbal Jan 1995

Seed Furrow Sidewall Smearing By Double Disk Openers , Muhammad Iqbal

Retrospective Theses and Dissertations

Seed furrow sidewall smearing by planter double disk openers in clay loam and loam soils was investigated in field and growth chamber experiments. Treatment variables were row preparation, soil moisture, and planting period. Evaluation parameters were soil bulk density, air permeability, cone index, emergence rate index and total emergence, and plant dry matter weight. The experiments were conducted in somewhat poorly drained soils near Ames, Iowa. The fields were not cultivated before planting and the residue from the previous year's corn was removed. Experiments were conducted in two cropping seasons. Each experiment consisted of a factorial design of three ...


Water Reuse In Fermentations , Tzu-Yin Hsiao Jan 1995

Water Reuse In Fermentations , Tzu-Yin Hsiao

Retrospective Theses and Dissertations

This work was undertaken to investigate the feasibility of reusing the process effluent from fermentation processes to minimize the liquid waste. Two fermentations with different characteristics were chosen as model fermentations for development of principles. The first was a yeast fermentation that requires high levels of carbon substrate for production of intracellular lipid. The second was a bacterial fermentation requiring high levels of nitrogen in the medium for production of lysine. The latter is used for commercial production of lysine;In the study of the first model fermentation, Apiotrichum curvatum, an oleaginous yeast, was used as the working culture. Spent ...


Impact Of Artificial Reef Associates On Macrobenthic Community Structure In Florida Bay, Heinz Michael Proft Jan 1995

Impact Of Artificial Reef Associates On Macrobenthic Community Structure In Florida Bay, Heinz Michael Proft

Dissertations, Theses, and Masters Projects

No abstract provided.