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Full-Text Articles in Life Sciences

Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer May 2023

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 …


Hydrologic Controls On Phosphorus Speciation And Mobilization In A Subalpine Watershed (East River, Colorado), Lucia Isobel Arthen-Long Oct 2021

Hydrologic Controls On Phosphorus Speciation And Mobilization In A Subalpine Watershed (East River, Colorado), Lucia Isobel Arthen-Long

Masters Theses

The cycling of phosphorus (P) through floodplain environments is critical to ecosystem productivity and has significant implications on both water quality and soil fertility. P export from soils in response to saturation has been well documented, but the relative vulnerability of specific P pools to mobilization remains poorly constrained, as do the mechanisms mediating its release. The prediction of P availability in and export from mountainous floodplain soils is of great importance as global climate change is projected to significantly alter precipitation regimes in alpine systems. This study combined a thorough characterization of P distribution across a hillslope to floodplain …


Effects Of Traditional And Microbially-Focused Restoration Techniques On Soil Communities In Tallgrass Prairies, Zachary J. Whitacre Jun 2021

Effects Of Traditional And Microbially-Focused Restoration Techniques On Soil Communities In Tallgrass Prairies, Zachary J. Whitacre

Masters Theses

Tallgrass prairies have virtually disappeared in many parts of their former range due to the conversion of this ecosystem to farmland. In more recent years there have been efforts to restore these prairies on reclaimed agricultural land. However, these restored prairies do not resemble their remnant counterparts in many ways, such as in soil microbial community composition and metrics related to carbon storage. In Chapter 1, I show that bacterial communities in a restored prairie and an adjacent remnant prairie in southwest Michigan differ in their immediate and longer-term responses to prescribed fire, a commonly used prairie restoration and maintenance …


Effects Of Am Fungi From Conventional And No-Till Michigan Crop Fields On Plant And Soil Health, Derek Bennett May 2021

Effects Of Am Fungi From Conventional And No-Till Michigan Crop Fields On Plant And Soil Health, Derek Bennett

Masters Theses

Centuries of conventional till (CT) management in agriculture has depleted soil organic matter (SOM) by over 50%. While only comprising 5% in most soils, SOM provides soil with fertility and productivity. To compensate for SOM depletion, producers have been forced to increase their reliance on fertilizer and irrigation to maintain yields. In the coming decades, climate change is expected to challenge food production and threaten an already fragile system. With no remaining land left to cultivate, conservation management strategies such as no-till (NT) look to restore SOM and increase the resilience of food production for an ever growing, increasingly food …


Long-Term Impacts Of Conservation Management Practices On Soil Carbon Storage, Stability, And Utilization Under Cotton Production In West Tennessee, Candace Brooke Wilson Dec 2015

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 …


Revealing The Ecological Role Of Gemmatimonadetes Through Cultivation And Molecular Analysis Of Agricultural Soils, Mariam Naomi Fawaz May 2013

Revealing The Ecological Role Of Gemmatimonadetes Through Cultivation And Molecular Analysis Of Agricultural Soils, Mariam Naomi Fawaz

Masters Theses

Bacteria belonging to phylum Gemmatimonadetes are frequently detected in a variety of environments using culture-independent methods. Despite their ubiquity and prevalence, almost nothing is known about their physiology or ecology because so few strains have been isolated. The first objective of this study was to determine the distribution of Gemmatimonadetes within soil aggregates and the response of the relative abundance of Gemmatimonadetes to dry/wet cycling and soil management. The second objective was to analyze the effects of soil management, aggregate size, and atmospheric conditions on cultivability of Gemmatimonadetes. Universal and Gemmatimonadetes-specific 16S rRNA gene primers were used to …