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Full-Text Articles in Physical Sciences and Mathematics

Cover Crop Effects On Infiltration, Aggregate Stability, And Water Retention On Loessial And Alluvial Soils Of The Lower Mississippi River Valley, Shelby G. Lebeau Dec 2021

Cover Crop Effects On Infiltration, Aggregate Stability, And Water Retention On Loessial And Alluvial Soils Of The Lower Mississippi River Valley, Shelby G. Lebeau

Graduate Theses and Dissertations

Cover crops are a widely considered practice to improve soil health in the form of erosion control, organic matter additions, and improving water-holding capacity. Despite the well-documented benefits, little is known about the effect of cover crops on soils in the Lower Mississippi River Valley (LMRV), an area historically dominated by intensive cultivated agriculture, with soils prone to erosion, and unsustainable aquifer withdrawals for irrigation. The main objective of this study was to evaluate the effects of cover crops [with cover crops (CC) and without cover crops (NCC)] on near-surface soil physical/chemical- and infiltration-related properties, aggregate stability, and water retention. …


Forced And Unforced Permafrost Changes In The Northern Hemisphere During 1901-2100, Hong Guo Dec 2021

Forced And Unforced Permafrost Changes In The Northern Hemisphere During 1901-2100, Hong Guo

Graduate Theses and Dissertations

Permafrost regions are very sensitive to rapid changes in climate and environment. In recent decades, there has been growing interest to better understand the permafrost degradation over the Northern Hemisphere in the context of human-induced climate change. Understanding permafrost dynamics is not only important for infrastructure but also for environmental protection in cold regions. In-situ permafrost measurements are important for assessing permafrost conditions. However, direct permafrost observations are sparse and asymmetrical in both spatial and temporal coverage. Active layer thickness (ALT) modeling is another approach that can overcome many of these limitations, but the models have large uncertainty in predicting …


Assimilation Of Seasonal Moisture Variability In North America And Asia For The Last Millennium, Chang Liu Jul 2021

Assimilation Of Seasonal Moisture Variability In North America And Asia For The Last Millennium, Chang Liu

Graduate Theses and Dissertations

The seasonal tree-ring chronologies that recorded discrete moisture signal for warm and cool season have been used to reconstruct the North America Seasonal Precipitation Atlas (NASPA) by the point-by-point regression method, and the results indicated that they can fairly reproduce the seasonal precipitation variability in the past. Compared with reconstructions using only paleoclimate proxy data, the paleoclimate data assimilation (PDA) considers both proxy data and climate model output, so the PDA reconstructions are consistent with both the climate signals reflected by the proxy data and the physical mechanisms represented by climate models. Based on the tree rings with discrete seasonal …


Managing Climate Change And Weather Extremes For Nature-Based Tourism Organizations In The United States, Siyao Ma May 2021

Managing Climate Change And Weather Extremes For Nature-Based Tourism Organizations In The United States, Siyao Ma

Graduate Theses and Dissertations

Weather and climate serve as profound motivators for tourism travels. Much of the United States (US) has experienced a warming trend as well as higher extreme weather frequency, and the trends are projected to be continued. Consequently, the changing climate is expected to have both direct and indirect impacts on tourism decision-making and travel patterns due to the complex relationship between climate, weather, and outdoor recreation. Climate resources capture the integrated effects of varied meteorological variables that interact with humans in different ways and can be categorized along a spectrum of quantifiable values. This dissertation proposed a Camping Climate Index …


Quantifying The Leaching Of Nutrients And Metals In A Pasture Soil As Affected By Excreta Of Ruminants Fed Alternative Diets, Ian Kennedy May 2021

Quantifying The Leaching Of Nutrients And Metals In A Pasture Soil As Affected By Excreta Of Ruminants Fed Alternative Diets, Ian Kennedy

Graduate Theses and Dissertations

The leaching of nitrate through the soil profile and into adjacent water systems has been a leading cause of water pollution and results in the loss of a valuable nutrient from animal production systems. Forage-based animal production systems may be improved through manipulation of animal diets that incorporate tannins and total polyphenolic compounds with feed, increasing the amount of nitrogen (N) retained by an animal/decreasing rates of digestion and altering the N-containing compounds that are excreted and deposited onto soil. Incorporating the forage legumes sericea lespedeza (Lespedeza cuneate [Dumont de Courset] G. Don) and lablab (Lablab purpurues L.) into the …