Physical Sciences and Mathematics Commons^™

Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer

Masters Theses

Cover crops provide multiple environmental benefits that improve both soil and water quality; however, farmers only utilize them on approximately 5% of harvested U.S. cropland. Low adoption rates are attributed to yield impact concerns, seed and planting costs, and lack of advocacy. This study, which began in October 2019, assessed the effects of nitrogen rate and cover crop diversity on weed biomass, soil coverage, in-situ residue decomposition, soil nitrogen and phosphorus availability, and cash crop yield to better understand the costs and benefits of cover crop adoption at two locations in Tennessee (Milan and Spring Hill). Treatments were replicated 4 …

Factors Affecting Groundwater Nitrate Concentration In Madinah Area, Saudi Arabia, Majed M. Almutairi

Masters Theses

High levels of nitrate in groundwater are a serious problem in Madinah Area, Saudi Arabia. Identifying factors affecting groundwater nitrate contamination is important for managing groundwater quality. This study examined factors that have significant impacts on the high level of groundwater nitrate in Madinah Area. Factors examined included well-depth and land cover. Relationships between variables were explored using three statistical approaches: the Kruskal-Wallis test and two types of regression (ordinary least squares [OLS] and geographically weighted regression [GWR]).

Nitrate concentration data show that 73% of obtained groundwater samples exceeded the United States Environmental Protection Agency (EPA) maximum contaminant level (MCL) …