UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
3 results
Search Results
Item Quantifying the impacts of climate-smart farming practices for improved management and long-term carbon storage(2023) Boniface, Helen S; Tully, Katherine L; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Within agricultural production there is tension between feeding a rapidly growing population and conserving the finite resources at the foundation of our agroecosystems. Fortunately, in recent decades there has been a growing focus on farming practices that promote long-term soil health, land productivity, and resilience to climate change. The term ‘conservation agriculture’ encompasses practices that 1) promote minimum soil disturbance, 2) maintain permanent soil cover, and 3) diversify plant species. This research evaluated several conservation agriculture practices for their ability to deliver desired agroecosystem services across the Northeastern US. In the first study, a cover crop mixture field experiment was implemented in seven states to evaluate how climatic, edaphic, and management conditions affected the performance of cover crop bicultures that included species with varying functional traits. Seeding rate recommendations for mixtures are typically developed at the regional level, thus cover crop performance is highly variable due to site-level conditions and competition among species. Our results indicated that expected spring growing degree days and baseline soil fertility (i.e., inorganic N) are the most significant variables to consider when designing site-specific cover crop mixtures. The second study assessed the effects of long-term management on soil organic carbon (SOC) dynamics in mid-Atlantic grain cropping systems. At the time of sampling, five unique systems (two conventional, three organic) had been continuously managed for 25 years, representing a range of tillage and fertility practices and rotational complexities. Results showed SOC loss in all systems over time regardless of management, likely because of high baseline SOC stocks from long-term perennial forage production prior to research plot establishment. However, cropping systems that best maintained SOC over time included management with minimal soil disturbance, frequent manure inputs, and/or greater rotational diversity through perennial cropping or cover cropping. Both studies increase our understanding of the ability of specific conservation practices to support agroecosystem biodiversity, long term soil health, and potential carbon sequestration.Item The effect of salinity on species survival and carbon storage on the Lower Eastern Shore of Maryland due to saltwater intrusion(2019) de la Reguera, Elizabeth; Tully, Kate; Palmer, Margaret; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)As sea levels continue to rise, coastal ecosystems are vulnerable to saltwater intrusion (SWI), the landward movement of sea salts. Specifically, in coastal farmlands, we expect SWI to drive changes in plant species composition and carbon (C) storage. As soils salinize, standard crops (i.e. corn, soybean, and wheat) can no longer survive and farmers must consider alternatives. Further, transitioning agricultural fields may become C sinks as SWI advances inland and farmlands begin to resemble tidal wetlands. My objectives were to determine: (1) the effect of SWI on the germination of standard and alternative crop species, and (2) the C storage potential of salt-intruded farmlands. Most standard and alternative crops were intolerant to high levels of osmotic and ionic stress at the germination stage. However, sorghum and salt-tolerant soybean showed promise in field experiments. I show that agricultural fields exposed to SWI have a high potential to store C in soils.Item ARTHROPOD COMMUNITIES IN RIPARIAN GRASS BUFFERS AND ADJACENT CROPS(2008-05-31) Nelson, Jessica Lynn; Dively, Galen; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Riparian buffers composed of either native warm season or non-native cool season grasses are commonly planted alongside crop fields. Although their water quality function is well documented, few studies have examined grass buffers as habitat for arthropod communities. The aerial and epigeal arthropods were surveyed using pitfall traps and sticky cards to assess the effects of both grass types on community structure in the buffer and adjacent crop. I predicted that warm season grasses would provide favorable habitat for more diverse and abundant arthropod populations, particularly natural enemies. The weight of evidence did not support my prediction and suggests that cool season grass buffers provide equivalent, if not better habitat for arthropods than warm season grasses. Coupled with higher food quality, cool season species green-up much earlier than warm season grasses in the spring and provide food resources for many herbivores and natural enemies.