Physical Sciences and Mathematics Commons^™

Long-Term Impacts Of Conservation Management Practices On Soil Carbon Storage, Stability, And Utilization Under Cotton Production In West Tennessee, Candace Brooke Wilson

Masters Theses

Biogeochemical cycling of soil carbon (C) is heavily influenced by conservation agricultural (CA) practices. This study examined SOC stability under three CA practices: reduced nitrogen (N) fertilizer application rate, cover cropping, and zero-tillage implemented for 31 years. Respiration rates measured from a 602-day incubation period were fitted to a double-pool first order exponential model of SOC decomposition. The active [respired] SOC pool showed distinct differences between applications of reduced (34N kg ha^-1 [-1]) and high fertilization rates (101N kg ha^-1) combined with tillage, and suggest that high fertilizer applications with conventional tillage allocated more C into a …

Impacts Of Changing Snowmelt Timing On Non-Irrigated Crop Yield, Erin Murray

Boise State University Theses and Dissertations

As climate changes, the final date of spring snowmelt is projected to occur earlier in the year within the western United States. This earlier snowmelt timing may impact crop yield in snow-dominated watersheds by changing the timing of water delivery to agricultural fields. There is considerable uncertainty about how agricultural impacts of snowmelt timing may vary by region, crop type, and practices like irrigation vs. dryland farming. We utilize parametric regression techniques to isolate the magnitude of impact snowmelt timing has had on historical crop yield independently of climate and physiographic variables that also impact yield. To do this, we …

A Pump Monitoring Approach To Irrigation Pumping Plant Performance Testing, William Merritt Mcdougall

Graduate Theses and Dissertations

Traditionally, irrigation pumping plants have been tested using an instantaneous appraoch, which tests performance parameters over a very short time interval. Using this method, the tester measures the necessary work and energy use parameters to calculate the desired pumping plant performance values. The primary limitation of this approach is its inability to determine the season long efficiency of an irrigation pumping plant.

A new approach to evaluating irrigation pumping plant performance is the use of pump monitoring systems which use high frequency, real-time data collection and telemetry to relay information directly from the pump to the user. This method of …

Accuracy Of Supervised Classification Of Cropland In Sub–Saharan Africa, Sarah Lynn Lewis-Gonzales

Masters Theses

Mali is a country in sub–Saharan Africa where monitoring of cropped land area would greatly benefit food security initiatives and aid organizations. More importantly village–scale studies on cropped land are fundamental to making a difference in the way we look at cropped land area and food availability in this region of the world. Using Landsat surface reflectance imagery and World View–2 derived labeled data, this study focuses on accuracy of supervised classification methods while addressing various levels of scale. Several classification methods are taken into account to determine the best method possible to produce cropped area estimates using this data. …

Model Of Residence Time And Analysis Of Nitrogen Removal For Two Constructed Wetlands At The Franklin Demonstration Farm In Lexington, Illinois, Emma Singh Baghel

Theses and Dissertations

Pollution from nonpoint agricultural runoff has become a major problem facing our streams and rivers today. Not only are fish and aquatic life affected, but so is the quality of our drinking and recreational water resources. Studies have shown that wetlands have proven to be the most cost-effective and low maintenance method of removing nonpoint or diffused contaminate inputs. The biological processes and removal of nutrients in wetlands depend on the total surface area available for microbial activity in the soil and a certain period of water retention time. Since chemical processes take time, the measure of residence time is …

Essays On Air Pollution, Global Warming And Agriculture Productivity., Ridhima Gupta Dr.

Doctoral Theses

This dissertation consists of three chapters, each of which deals with a particular aspect of environmental policy. The first chapter focuses on the determinants of open-field burning of rice-residue with the aim of analysing possibilities for its regulation. Open field burning is the second-largest contributor to black carbon in South Asia, the second most important greenhouse agent after carbon dioxide. Thus, dealing with the problem of burning of rice residue will tackle a significant proportion of the black carbon emissions released into the atmosphere. The third chapter proposes a new approach for estimating the contribution of agricultural fires to atmospheric …

Three Essays On The Impact Of Global Warming In India., Eshita Gupta Dr.

Doctoral Theses

This dissertation consists of three chapters. The Örst chapter studies the impact of climate change on electricity demand in Delhi using daily data on electricity demand and apparent temperature for the period 2000-09. It estimates a semi-parametric variable coe¢ - cient model that allows for a non-linear relationship between temperature and electricity to shift over time, a feature that is necessary to incorporate given the rapid economic growth in India. As evident from previous studies, electricity demand is a U-shaped function of temperature. Three results from our analysis have important implications for electricityclimate policy: Firstly, the rising part of the …

Stoichiometric Controls On Denitrification In High Nitrate Watersheds, Brian Grebliunas

Theses and Dissertations

Watershed biogeochemistry throughout Midwestern agroecosystems have been altered through hydrologic manipulation and over-application of nitrogenous fertilizers. As a result, nitrate (NO3-N) export from subsurface drainage has negative impacts on local and downstream ecosystem health. Wetland installation has proven to be a viable option for targeted management where a large proportion of NO3-N is removed through the bacterially mediated process denitrification. For denitrification to maintain high rates under prolonged NO3-N saturation, a stable supply of labile dissolved organic carbon (DOC) is required. The focus of this dissertation was to study how the stoichiometry of agricultural wetlands limits denitrification within a controlled …

A Qualitative Analysis Of Migrant Women Farmworkers' A Qualit Ative Analysis Of Migrant Women Farmworkers’ Perceptions Of Maternal Care Management, Stacey A. Pilling

Walden Dissertations and Doctoral Studies

The purpose of this phenomenological study was to examine migrant women farmworkers' views of perinatal care management while working in the fields. Like men, women migrant farmworkers are exposed to many physical, chemical, and biological hazards that pose human health risks. However, women of childbearing age are at an increased risk of having reproductive health difficulties and adverse pregnancy outcomes, and the infant mortality rate among migrant farmworkers is estimated to be twice the national average. Perinatal care is a critical factor in reducing adverse outcomes for perinatal and newborn mortality. Face-to-face interviews were conducted with 15 migrant women farmworkers …

Ensuring Our Future Or Sowing The Seeds Of Our Own Destruction? Crop Insurance And Water Use In Texas, Michael Shapiro

Pomona Senior Theses

Agriculture is the largest consumer of water in the United States. Policies that affect agriculture therefore have the potential to have a large effect on the overall use of water. Crop insurance is one such policy, which was found to significantly increase water use in the state of Texas. Much, but not all of this effect can be explained by an increase in planting density, and results vary widely by crop and by region.