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Retrospective Theses and Dissertations

Environmental Sciences

Agricultural engineering

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Full-Text Articles in Life Sciences

Integration Of Remote Sensing And Crop Growth Modeling For Nitrogen Management Decision Support In Corn , Kelly Robert Thorp Jan 2006

Integration Of Remote Sensing And Crop Growth Modeling For Nitrogen Management Decision Support In Corn , Kelly Robert Thorp

Retrospective Theses and Dissertations

This dissertation describes efforts to move toward a completely integrated remote sensing and crop growth modeling tool for developing precision nitrogen management recommendations for corn. Aerial hyperspectral remote sensing imagery collected throughout the 2004 growing season was used to estimate corn plant stand density, and a machine vision system was used to map corn population on the ground. Multiple linear regression analysis was used to assess the ability of all combinations of three reflectance bands to estimate corn plant population at resolutions of 2 m, 6 m, and 10 m. Coefficients of multiple determination of up to 0.82 were ...


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 ...


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 ...


Assessment And Simulation Of Atrazine As Influenced By Drainage And Irrigation: An Interface Between Rzwqm And Arcview Gis , Ana Sofia De Oliveira Nobre Azevedo Jan 1998

Assessment And Simulation Of Atrazine As Influenced By Drainage And Irrigation: An Interface Between Rzwqm And Arcview Gis , Ana Sofia De Oliveira Nobre Azevedo

Retrospective Theses and Dissertations

Atrazine is the most frequently detected herbicide in groundwater. For these reasons, atrazine's dynamics need to be studied, and work is needed to develop and calibrate mathematical models to help in determining best management practices to minimize contamination. This study was designed to make a small contribution in solving some of the environmental related problems;In the first part of this study, macroporosity of an agricultural soil in Iowa was characterized. This study confirmed that under saturated and partially saturated flow conditions, macropore flow was a dominant mechanism for water and chemical transport;Atrazine's movement through the soil ...


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 ...


Modelling And Evaluation Of A Cistern-Based Ground-Coupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary Jan 1994

Modelling And Evaluation Of A Cistern-Based Ground-Coupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary

Retrospective Theses and Dissertations

This research details the analysis of a ground-coupled heat pump system which utilizes a 20,000 gallon well-water storage tank as a source of heating and cooling. It addresses the feasibility of such a system and discusses the system in terms of energy efficiency--first law conservation analysis. The potential use of this type of system for the control of sensitive thermal environments involving swine is also evaluated;The goal of this research was to investigate ISU's SNMRC heat pump system. Specific objectives were: (1) To evaluate the system in terms of heat exchanger and heat pump efficiencies. (2) To ...


Measurement And Simulation Of Water Table Management Effects On Groundwater Quality , Prasanta Kumar Kalita Jan 1992

Measurement And Simulation Of Water Table Management Effects On Groundwater Quality , Prasanta Kumar Kalita

Retrospective Theses and Dissertations

The goal of this study was to investigate the effect of various water-table management (WTM) practices on corn growth and yield and agricultural chemical concentrations in shallow groundwater. Field experiments were conducted for three years (1989-91) at the research sites near Ames and Ankeny. Water-table depths of 0.3, 0.6, and 0.9 m were maintained in field lysimeters at the Ames site, and variable water-table depths were maintained in a subirrigation field at the Ankeny site;Photosynthesis measurements were made regularly during the growing season, and yield data were collected at harvest. In 1989, a relatively dry year ...


Modeling Spatial Variability And Transport Processes In A Glacial Till Soil , Binayak Prasad Mohanty Jan 1992

Modeling Spatial Variability And Transport Processes In A Glacial Till Soil , Binayak Prasad Mohanty

Retrospective Theses and Dissertations

The objective of this study was to investigate the spatial variability of different physical and chemical properties of soils, and their role on transport processes of chemicals to groundwater sources in a glacial till soil of central Iowa;Measurements were made to determine the in-situ saturated hydraulic conductivity (K[subscript] sat) of a glacial till soil at sixty six sites in a tillage established plot. One hundred thirty-two data points on K[subscript] sat collected at two soil depths along two bisecting perpendicular transects, were used to develop semivariogram models, in conjunction with split-window median polish approach. Nested structure with ...


Efficient Herbicide Application To Reduce Environmental Losses , Steven Kent Mickelson Jan 1991

Efficient Herbicide Application To Reduce Environmental Losses , Steven Kent Mickelson

Retrospective Theses and Dissertations

A point-injection system has successfully been designed to inject and incorporate herbicides applied with water into the soil profile in a band. This point-injection cylinder (PIC) can incorporate herbicides in a single pass through the field while leaving the soil surface virtually undisturbed. The PIC functions effectively on both bare soil surfaces and soil surface covered with crop residue;The relative persistence of banded herbicides (alachlor, atrazine, and propachlor) using the PIC and a band sprayer was compared in a field study. A bare soil surface and a soil covered with an average of 79 percent corn residue were used ...


A Simulation Study Of Corn Production And Low-Temperature Drying For Central Iowa , Gary Richard Van Ee Jan 1980

A Simulation Study Of Corn Production And Low-Temperature Drying For Central Iowa , Gary Richard Van Ee

Retrospective Theses and Dissertations

Two computer models, CORNSIM and FALDRY, were developed and used to conduct a simulation study of corn production and low-temperature drying for Central Iowa conditions. CORNSIM simulates a complete corn production enterprise. Given a specific management strategy, machinery capacity, and cropping season, CORNSIM simulates planting, crop development, yield, and harvesting. CORNSIM was developed to provide the simulated flow of harvested grain. FALDRY simulates a system of low-temperature corn drying bins. FALDRY inputs include bin specifications, weather data, and the incoming flow of harvested grain. FALDRY was developed to predict the success or failure of a low-temperature corn drying system and ...


A Solar-Heated Grain Dryer For The Tropics , Virgilio G. Gayanilo Jan 1980

A Solar-Heated Grain Dryer For The Tropics , Virgilio G. Gayanilo

Retrospective Theses and Dissertations

No abstract provided.


Heat Transfer In A Beef Manure Anaerobic Digester , Thomas Hobson Greiner Jan 1980

Heat Transfer In A Beef Manure Anaerobic Digester , Thomas Hobson Greiner

Retrospective Theses and Dissertations

In cold climates it was determined that the heat loss from the hot effluent of a beef manure anaerobic digester represented a sizeable portion of the energy production of the digester. This suggested an effluent to influent heat exchanger was necessary. Available heat exchangers were unsuitable;A different concept heat exchanger using a vertical flat plate for the heat transfer surface with the hot and cold flows passing on either side was then considered. The exchanger would be divided into a number of tanks with an overall counterflow arrangement. The extra tanks and the counterflow arrangement would increase the effectiveness ...


Minimizing Cold Weather Energy Demand Of Swine Confinement Housing , Raymond Leroy Huhnke Jan 1980

Minimizing Cold Weather Energy Demand Of Swine Confinement Housing , Raymond Leroy Huhnke

Retrospective Theses and Dissertations

A computer model was developed to predict the thermal and electrical energy required to provide a controlled atmospheric environment for life-cycle swine production. Using short time-interval climatological data recorded in central Iowa, the simulation can estimate the total energy requirements of a swine facility based on building construction, floor type, and environmental management choices. The simulation considers building conduction, solar, and ventilation heat transfers as well as animal heat production. Ventilation is based on temperature control and recommended practice to maintain optimum animal performance;The model was used to predict January energy demands for nursery, finishing, and farrowing buildings having ...


Heat Transfer And Mixing Energies In Digesting Beef Manure, David Robert Smith Jan 1980

Heat Transfer And Mixing Energies In Digesting Beef Manure, David Robert Smith

Retrospective Theses and Dissertations

No abstract provided.


A Land-Phase Hydrologic Model For Strip Mined Lands , James M. Gregory Jan 1977

A Land-Phase Hydrologic Model For Strip Mined Lands , James M. Gregory

Retrospective Theses and Dissertations

No abstract provided.


Pumping Irrigation Wells For Drainage Of Luton Soils, George James Kriz Jan 1962

Pumping Irrigation Wells For Drainage Of Luton Soils, George James Kriz

Retrospective Theses and Dissertations

No abstract provided.


Water Supply, Equipment, And Labor Requirements For Irrigation Of Iowa Field Crops, Morton W. Bittinger Jan 1951

Water Supply, Equipment, And Labor Requirements For Irrigation Of Iowa Field Crops, Morton W. Bittinger

Retrospective Theses and Dissertations

No abstract provided.


Level Terrace Design As Affected By Hydrologic Factors, Harold P. Guy Jan 1951

Level Terrace Design As Affected By Hydrologic Factors, Harold P. Guy

Retrospective Theses and Dissertations

No abstract provided.


Performance And Operating Costs Of Tile Trenching Machines, Leonard Lyle Devries Jan 1951

Performance And Operating Costs Of Tile Trenching Machines, Leonard Lyle Devries

Retrospective Theses and Dissertations

No abstract provided.