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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
Advances In Nutrient Management Of Grass Seed Crops, René Gislum, Birte Boelt
Advances In Nutrient Management Of Grass Seed Crops, René Gislum, Birte Boelt
IGC Proceedings (1997-2023)
Nutrient management of herbage grass seed crops is just as complex as for other agricultural crops when the aim is to optimise economic net return and minimise environmental impact. The use of economic optimum nitrogen (N) application rate (ECO-N) defined as the N application rate that maximise net return for the seed grower is an easy and applicable method for seed growers. Besides the economic advantages of implementing ECO-N there is an additional positive environmental effect as ECO-N is lower than the N rate that maximises seed yield and a lower N application rate will concomitantly lower the potential risk …
Characterizing Dryland Ecosystems Using Remote Sensing And Dynamic Global Vegetation Modeling, Abdolhamid Dashtiahangar
Characterizing Dryland Ecosystems Using Remote Sensing And Dynamic Global Vegetation Modeling, Abdolhamid Dashtiahangar
Boise State University Theses and Dissertations
Drylands include all terrestrial regions where the production of crops, forage, wood and other ecosystem services are limited by water. These ecosystems cover approximately 40% of the earth terrestrial surface and accommodate more than 2 billion people (Millennium Ecosystem Assessment, 2005). Moreover, the interannual variability of the global carbon budget is strongly regulated by vegetation dynamics in drylands. Understanding the dynamics of such ecosystems is significant for assessing the potential for and impacts of natural or anthropogenic disturbances and mitigation planning, and a necessary step toward enhancing the economic and social well-being of dryland communities in a sustainable manner (Global …
The Role Of Sediment Resuspension In Estuarine Inorganic Nutrient Cycling, Kirsten Jo Ayres
The Role Of Sediment Resuspension In Estuarine Inorganic Nutrient Cycling, Kirsten Jo Ayres
Theses and Dissertations
Time-scaling of estuarine inorganic nitrogen cycling contains many assumptions due to biogeochemical interactions. Nitrogen, often a limiting factor for primary production, is transformed and utilized by many estuarine organisms. Inorganic nitrogen is especially high in porewater. High nutrient pore water, contained within the interstitial spaces of sediment, has been assumed to influx high concentrations of inorganic nutrients into surface waters during resuspension events. These short-term resuspension events rapidly introducing high concentration of nutrients into the water column. In order to determine the internal time scale of inorganic nitrogen cycling, a box-model nutrient budget, horizontal in situ transects, and vertical nutrient …
Does Intensification Of Grassland And Forage Use Lead To Efficient, Profitable And Sustainable Ecosystems?, Oene Oenema, Cecile De Klein, Marta Alfaro
Does Intensification Of Grassland And Forage Use Lead To Efficient, Profitable And Sustainable Ecosystems?, Oene Oenema, Cecile De Klein, Marta Alfaro
IGC Proceedings (1997-2023)
The increasing demand for safe and nutritional dairy and beef products in our globalizing world, together with the needs to increase resource use efficiency and to protect biodiversity, provide strong incentives for intensification of grassland and forage use. This paper addresses the question in the title. Firstly, we present some notions about ‘intensification of agricultural production’. Secondly, we discuss the intensification of grassland-based dairy production in The Netherlands (NL), Chile and New Zealand (NZ). Finally, we arrive at some conclusions. External driving forces and ‘the law of the optimum’ provide strong incentives for intensification, i.e., for increasing the output per …
Reconstructing Geographic And Trophic Histories Of Fish Using Bulk And Compound-Specific Stable Isotopes From Eye Lenses, Amy A. Wallace
Reconstructing Geographic And Trophic Histories Of Fish Using Bulk And Compound-Specific Stable Isotopes From Eye Lenses, Amy A. Wallace
USF Tampa Graduate Theses and Dissertations
The present research examined the viability and utility of eye lenses as a source of lifetime stable-isotope records in fish. It is presented in three sections. The first section compared bulk isotopic variation (bulk analysis) within fish eye-lenses at two temporal resolutions and compared patterns obtained from left and right eyes. The first temporal resolution was lower in an attempt to expose broad-scale isotopic changes during life while reducing effort and cost. This approach did reveal lifetime patterns, but tended to miss certain life events, particularly during early life. The second resolution was higher and provided detail that was missed …
Short Term Effects Of Hurricane Irma And Cyanobacterial Blooms On Ammonium Cycling Along A Freshwater-Estuarine Continuum In South Florida, Justyna J. Hampel, Mark J. Mccarthy, Megan H. Reed, Silvia E. Newell
Short Term Effects Of Hurricane Irma And Cyanobacterial Blooms On Ammonium Cycling Along A Freshwater-Estuarine Continuum In South Florida, Justyna J. Hampel, Mark J. Mccarthy, Megan H. Reed, Silvia E. Newell
Faculty Publications
Lacustrine and coastal systems are vulnerable to the increasing number and intensity of tropical storms driven by climate change. Strong winds associated with tropical storms can mobilize nutrients in sediments and alter nitrogen and phosphorus cycling, leading to amplification of preexisting conditions, such as eutrophication and cyanobacterial blooms (cyanoHABs). In 2016, Florida declared a State of Emergency within and downstream of Lake Okeechobee (LO) due to toxic cyanobacterial blooms (primarily Microcystis). The blooms originated in LO, but flood control measures released water from LO to the brackish St. Lucie Estuary (SLE). In September 2017, Hurricane Irma traversed the Florida …
Improved Estimates Of Tributary Nitrogen Load To Casco Bay, Maine, Whitley J. Gray
Improved Estimates Of Tributary Nitrogen Load To Casco Bay, Maine, Whitley J. Gray
Electronic Theses and Dissertations
Over the past two decades, total nitrogen (TN) concentrations have increased in Casco Bay (CBEP 2015). The sources of the increased nitrogen are poorly understood but occur with simultaneous population growth and land use changes. The total riverine nitrogen load to Casco Bay was previously estimated by Liebman and Milstead (2012) using the United States Geologic Survey’s (USGS) SPAtially Referenced Regression On Watershed attributes (SPARROW) model. The SPARROW model uses watershed characteristics, regional monitoring data and nitrogen source data to estimate nitrogen loading but was not validated using measurements of nitrogen in the Casco Bay watershed. This study attempts to …
Experimental Nitrogen Addition Alters Structure And Function Of A Boreal Bog: Critical Load And Thresholds Revealed, R. Kelman Wieder, Dale H. Vitt, Melanie A. Vile, Jeremy A. Graham, Jeremy A. Hartsock, Hope Fillingim, Et Al.
Experimental Nitrogen Addition Alters Structure And Function Of A Boreal Bog: Critical Load And Thresholds Revealed, R. Kelman Wieder, Dale H. Vitt, Melanie A. Vile, Jeremy A. Graham, Jeremy A. Hartsock, Hope Fillingim, Et Al.
Michigan Tech Publications
Bogs and fens cover 6% and 21%, respectively, of the 140,329 km2 Oil Sands Administrative Area in northern Alberta. Development of the oil sands has led to increasing atmospheric N deposition, with values as high as 17 kg N.ha-1yr-1; regional background deposition is N.ha-1yr-1. Bogs, being ombrotrophic, may be especially susceptible to increasing N deposition. To examine responses to N deposition, over five years, we experimentally applied N (as NH4NO3) to a bog near Mariana Lake, Alberta, unaffected by oil sands activities, at …
Limitations To Photosynthesis In Silver Bow And Blacktail Creeks, Isaiah Robertson
Limitations To Photosynthesis In Silver Bow And Blacktail Creeks, Isaiah Robertson
Graduate Theses & Non-Theses
Throughout Silver Bow Creek’s history, consideration of the photosynthetic communities that make heterotrophic life possible have often been overlooked since macroinvertebrates made up a majority of ecosystem health assessments. Silver Bow Creek has had minimal biological research outside of macroinvertebrate surveys, especially as it pertains to photosynthetic organisms. This study assessed the photosynthetic communities of Silver Bow Creek and their limitations by limiting available light and comparing uptake of nutrients during a 23-day incubation experiment conducted at four sites along the flow of Silver Bow Creek and Blacktail Creek. At each site, nine one-liter microcosms, filled with creek water and …
Dissolved Inorganic Nitrogen Dynamics In Swash Zone Sands Of Long Bay, Sc, Alexis F. Echols
Dissolved Inorganic Nitrogen Dynamics In Swash Zone Sands Of Long Bay, Sc, Alexis F. Echols
Honors Theses
A key component affecting the biogeochemistry of the sedimentary environment is pore water between grains of sediments. Sedimentary microorganisms are constantly modifying chemical compounds as part of their life functions which are then exchanged between the sediment column and the overlying water column. Dissolved inorganic nitrogen, a major element for life, takes on several forms including nitrate, nitrite, and ammonium which vary in concentration throughout the sediment and with respect to each other. The relative concentrations of these nitrogen species have been previously briefly explored in sandy columns, where redox gradients that control their relative concentrations can be fairly deep …
Stable Isotope Analysis Of Japan Sea And East China Sea Sediments: Late Pleistocene Paleoceanographic Reconstructions, Heather Dawn Black
Stable Isotope Analysis Of Japan Sea And East China Sea Sediments: Late Pleistocene Paleoceanographic Reconstructions, Heather Dawn Black
FIU Electronic Theses and Dissertations
The East Asian Monsoon system is an important dynamic of East Asian climates, affecting over one-third of the world’s population. Marginal seas within East Asia are ideal environments to study past fluctuations of monsoon intensities and durations as they are sensitive to climatic and glacio-eustatic sea level changes. This study focuses on continuous sedimentary sequences collected from three Integrated Oceanic Drilling Program Expedition 346 sites; Sites U1426 and U1427 in the Japan Sea and Site U1429 in the East China Sea. Elemental concentration (%TOC, %TN, and %CaCO3) and stable isotope ratios (δ13C and δ15N) …
Nitrogen And Phosphorus Uptake In An Urban Stream Ecosystem, Nicolette A. Sheffield
Nitrogen And Phosphorus Uptake In An Urban Stream Ecosystem, Nicolette A. Sheffield
Theses and Dissertations
Urban stream ecosystems are faced with high input levels of nitrogen (N) and phosphorus (P) from anthropogenic activities. N and P are important to plant growth and stream health; however, high levels can lead to algal blooms and eutrophication, a harmful effect to both aquatic life and water quality. Common urban sources of N and P include fertilizer, atmospheric deposition, stormwater outfall, and leaf-litter decomposition. Common urban stream features such as a flashier hydrograph, altered channel stability and morphology, increase in nutrient output (such as N and P), and heat retention, have been shown to result in an overall decrease …
The Role Of Small Reservoirs In Reducing Reactive N Export Via Denitrification, Margaret Phillips, Wil Wollheim
The Role Of Small Reservoirs In Reducing Reactive N Export Via Denitrification, Margaret Phillips, Wil Wollheim
Honors Theses and Capstones
Reactive nitrogen (N), which harms ecosystem health, has been increasing in the biosphere, leading to higher N export to coastal ecosystems. Although man-made reservoirs can be significant sources of greenhouse gases, they can also retain N, thus reducing N export. Because many dams are relics from industrial hydropower, their removal is becoming increasingly common. It is therefore crucial to understand the ecological tradeoffs of man-made reservoirs. While previous studies have examined nutrient budgets and denitrification at inputs and outputs of large reservoirs, small reservoir dynamics remain understudied. In this study, we measured inputs and outputs of NO3 and N …