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1
Hadwen, Wade Lynton, and w. hadwen@mailbox gu edu au. "Effects of Nutrient Additions on Dune Lakes on Fraser Island, Australia." Griffith University. Australian School of Environmental Studies, 2002. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030304.091718.
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Given the rapidly increasing visitation levels to Fraser Island, there is increasing concern that tourist activities may threaten the long-term ecological health of the region's unique dune lakes. This project aimed to investigate the consequences of tourist use of Fraser Island's dune lakes and to develop appropriate monitoring tools and management objectives in light of the projected increases in visitation levels in the foreseeable future. The initial phase of this research aimed to identify the relative importance of some of the most popular dune lakes on the island as key destinations for tourists. Tourist surveys, in conjunction with the development of a Tourist Pressure Index (TPI), which quantifies logistic, social and natural variables, identified Lakes McKenzie, Allom and Birrabeen as the lakes most at risk from excessive tourist use. In addition, analyses of water quality in 15 lakes on Fraser Island aimed to determine the current trophic status of dune lakes on Fraser Island and the ecological implications of tourist use of these systems. Detailed comparisons of nutrient and chlorophyll a concentrations in five popular dune lakes in February 1990 (data from Arthington et al. 1990) and February 1999 suggested that productivity has increased significantly in the past decade. More detailed examinations of nutrient and algal variables in five popular perched dune lakes revealed that while ambient nutrient and phytoplankton chlorophyll a concentrations remained relatively stable, periphyton chlorophyll a concentrations increased over the course of the 1999-2000 summer in most lakes. Significantly, these increases were found only in heavily visited (disturbed) sites in the clear lakes examined (McKenzie and Birrabeen). In these lakes, where algal growth is likely to be only limited by nutrient availability, tourist nutrient additions may stimulate excessive periphyton production. Experimental algal bioassays identified that phytoplankton and to a lesser degree periphyton growth was stimulated by nutrient additions in all five perched dune lakes. However, the degree to which growth was stimulated was both lake and nutrient (nitrogen versus phosphorus versus nitrogen + phosphorus) dependent, highlighting the variable nature of systems within a relatively small geographic range. Since periphyton biomass was higher in heavily visited areas of lakes and was likely to be stimulated by nutrient additions by tourists, stable isotope analyses of littoral zone food webs were conducted to quantify the percent contribution of periphyton to consumer diets. There was a trend towards higher periphyton contributions in systems identified as key tourist locations (on the basis of their TPI scores) and this indicates that increasing visitation may increase the contribution of periphyton to littoral zone food webs, both via increases in the quantity and quality of periphyton as a food resource. To further explore the contribution of periphyton in littoral zone food webs of heavily visited lakes, a 15N-tracer addition experiment was conducted to establish the fate of nutrient additions within the littoral zone. Nutrients were added in quantities that mimicked those likely from tourists, to enable a realistic appraisal of the fate of tourist additions. As expected, periphyton rapidly assimilated the added 15N-tracer and was found to be the first and most significant sink for nutrients entering the littoral zone. Finally, the results from this research were used to develop a conceptual model of nutrient enrichment for perched dune lakes on Fraser Island. The model indicates that although nutrient additions from tourists may lead to undesirable increases in periphyton biomass, the degree to which this is deemed to be a detrimental ecological outcome is likely to be mediated by water level fluctuations and the consumptive capacity of grazers. Given that excessive periphyton growth is likely to be seen as negative impact of tourism, regular periphyton monitoring (biomass and percent contribution to littoral zone food webs) should be built into an updated monitoring program for this series of dune lakes. Whilst the implementation of periphyton monitoring is likely to enable the early detection of deleterious impacts of excessive tourist use, it is likely that the long-term conservation of the region will, in the future, require the implementation of strict visitation level guidelines, to ensure that the irreversible consequences of long term additions of nutrients are ameliorated.
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Witkowski, Edward Tadeusz Fernando. "Response of a sand-plain lowland fynbos ecosystem to nutrient additions." Doctoral thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/8408.
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Bibliography: leaves 237-258.The effects of a complete factorial fertilizer addition of nitrogen (N), phosphorus (P) and a mixture of all essential nutrients excluding N and P (M) on various components of the soils and vegetation of a sand-plain lowland fynbos ecosystem at Pella, south-western Cape Province, South Africawere studied, namely: 1) Soil nutrient dynamics. 2) Phenology, shoot growth, reproductive output and nutrient acquisition in a proteoid (Leucospermum parile) and an ericoid (Phylica cephalantha) evergreen shrub. 3) Dry mass, phosphorus and nitrogen allocations to the various above and below ground organs of pre-reproductive and reproductive male plants of Thamnochortus punctatus (Restionaceae). 4) Litter production and nutrient return. 5) Above-ground phytomass, nitrogen and phosphorus contents of the representative plant growth forms in response to non-factorial addition of N, P and M. 6) Foliage projective cover of the representative growth forms of sand-plain lowland fynbos.
3
Hadwen, Wade. "Effects of Nutrient Additions on Dune Lakes on Fraser Island, Australia." Thesis, Griffith University, 2002. http://hdl.handle.net/10072/368084.
Full textAbstract:
Given the rapidly increasing visitation levels to Fraser Island, there is increasing concern that tourist activities may threaten the long-term ecological health of the region's unique dune lakes. This project aimed to investigate the consequences of tourist use of Fraser Island's dune lakes and to develop appropriate monitoring tools and management objectives in light of the projected increases in visitation levels in the foreseeable future.
The initial phase of this research aimed to identify the relative importance of some of the most popular dune lakes on the island as key destinations for tourists. Tourist surveys, in conjunction with the development of a Tourist Pressure Index (TPI), which quantifies logistic, social and natural variables, identified Lakes McKenzie, Allom and Birrabeen as the lakes most at risk from excessive tourist use.
In addition, analyses of water quality in 15 lakes on Fraser Island aimed to determine the current trophic status of dune lakes on Fraser Island and the ecological implications of tourist use of these systems. Detailed comparisons of nutrient and chlorophyll a concentrations in five popular dune lakes in February 1990 (data from Arthington et al. 1990) and February 1999 suggested that productivity has increased significantly in the past decade.
More detailed examinations of nutrient and algal variables in five popular perched dune lakes revealed that while ambient nutrient and phytoplankton chlorophyll a concentrations remained relatively stable, periphyton chlorophyll a concentrations increased over the course of the 1999-2000 summer in most lakes. Significantly, these increases were found only in heavily visited (disturbed) sites in the clear lakes examined (McKenzie and Birrabeen). In these lakes, where algal growth is likely to be only limited by nutrient availability, tourist nutrient additions may stimulate excessive periphyton production. Experimental algal bioassays identified that phytoplankton and to a lesser degree periphyton growth was stimulated by nutrient additions in all five perched dune lakes. However, the degree to which growth was stimulated was both lake and nutrient (nitrogen versus phosphorus versus nitrogen + phosphorus) dependent, highlighting the variable nature of systems within a relatively small geographic range.
Since periphyton biomass was higher in heavily visited areas of lakes and was likely to be stimulated by nutrient additions by tourists, stable isotope analyses of littoral zone food webs were conducted to quantify the percent contribution of periphyton to consumer diets. There was a trend towards higher periphyton contributions in systems identified as key tourist locations (on the basis of their TPI scores) and this indicates that increasing visitation may increase the contribution of periphyton to littoral zone food webs, both via increases in the quantity and quality of periphyton as a food resource.
To further explore the contribution of periphyton in littoral zone food webs of heavily visited lakes, a 15N-tracer addition experiment was conducted to establish the fate of nutrient additions within the littoral zone. Nutrients were added in quantities that mimicked those likely from tourists, to enable a realistic appraisal of the fate of tourist additions. As expected, periphyton rapidly assimilated the added 15N-tracer and was found to be the first and most significant sink for nutrients entering the littoral zone.
Finally, the results from this research were used to develop a conceptual model of nutrient enrichment for perched dune lakes on Fraser Island. The model indicates that although nutrient additions from tourists may lead to undesirable increases in periphyton biomass, the degree to which this is deemed to be a detrimental ecological outcome is likely to be mediated by water level fluctuations and the consumptive capacity of grazers. Given that excessive periphyton growth is likely to be seen as negative impact of tourism, regular periphyton monitoring (biomass and percent contribution to littoral zone food webs) should be built into an updated monitoring program for this series of dune lakes. Whilst the implementation of periphyton monitoring is likely to enable the early detection of deleterious impacts of excessive tourist use, it is likely that the long-term conservation of the region will, in the future, require the implementation of strict visitation level guidelines, to ensure that the irreversible consequences of long term additions of nutrients are ameliorated.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Australian Environmental Studies
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Irvine, K. "Zooplankton ecology and the effects of nutrient additions, habitat structure and fish predation on a freshwater ecosystem." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378900.
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Smith, Russell Stephen. "Mineral nutrient influxes and additions and their effects in a Banksia woodland ecosystem in South Western Australia." Thesis, Smith, Russell Stephen (1990) Mineral nutrient influxes and additions and their effects in a Banksia woodland ecosystem in South Western Australia. Honours thesis, Murdoch University, 1990. https://researchrepository.murdoch.edu.au/id/eprint/41520/.
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The objectives of this study were to gain information on the environmental effects of fertilizer drift. This was achieved by undertaking two separate investigations 1 firstly soil nutrient levels and vegetation composition along transects from farmland into a Banksia woodland were analysed to see how they co-varied. Secondly the effect of agricultural fertilizers on the growth, and nutrient and carbohydrate levels of selected shrub species from a Banksia woodland was investigated to determine if fertilizer stimulated shoot growth led to a reduction in root reserves which might diminish post-fire resprouting ability.
The first investigation, into fertilizer drift at Dardanup Block, a conservation reserve, found that most invasive exotic pasture species were restricted to physically disturbed areas at the edge of the reserve with only Hypochaeris glabra a small wind dispersed composite being common away from the edge. Total phosphorus values were highest in the paddock and declined with increasing distance into the reserve, levels were significantly higher in samples taken 0.5 m, 10 m and 20 m into the reserve than they were from those taken 60 m from the fence. Although potassium had been applied to the paddock for over twenty years there was no apparent effect on soil available potassium values at the edge of the reserve. The levels of this mineral and also total nitrogen within the woodland were correlated with native vegetation composition.
In the fertilization study the shrubs Kunzea ericifolia and Leucopogon conostephioides increased their mean biomass per new shoot in response to NPK fertilizer but not to superphosphate alone. The NPK fertilized 11 Kunzea plants connnenced shoot elongation earlier in the season than did the control plants. Increased growth was associated with higher proportions of phosphorus and potassium per unit of shoot nitrogen in Kunzea and increased K:N ratios in Leucopogon.
Levels of root non-structural carbohydrates in Kunzea and Leucopogon were not affected by increased shoot growth and the relatively low root reserves in these plants and their low root:shoot ratio are consistent with their lack of resprouting ability. Stir lingia which did not significantly increase its shoot growth in response to fertilization, had substantially higher root polysaccharide levels in the NPK plots which indicates that the added nutrients stimulated a higher rate of photosynthesis. The relatively high root: shoot ratio and root non-structural carbohydrate levels of Stirlingia are probably the reason for its strong resprouting ability.
From the results of these studies it is proposed that although superphosphate influx increases the levels of phosphorus on roadsides and at the edges of reserves it alone probably doesn't adversely affect the life strategies of native species, though it may favour exotic species. Longer term studies would be needed to separate the effects of continuing nutrient influx on vegetation composition from those of overfrequent burning and various other environmental changes and disturbances associated with "edge" habitats.
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Camenzind, Tessa [Verfasser]. "Responses of arbuscular mycorrhizal fungi to nutrient additions in a tropical montane forest of Southern Ecuador / Tessa Camenzind." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1098185293/34.
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Rhein-Welker, Deanna. "Performance and nutrient digestibility in weanling pigs as influenced by yeast culture, whey, and fiber additions to starter diets." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07292009-090510/.
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Bergholm, Johan. "Long-term effects of enhanced nitrogen and sulphate additions on soil acidification and nutrient cycling in a Norway spruce stand /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6099-9.pdf.
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Maloney, Caitlin E. "The effects of micronutrient additions on soil invertebrate activity and community structure along a successional gradient." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1498074605780196.
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Perkins, Rupert Gordon. "Phosphorus limitation in Alton Water reservoir." Thesis, University of Essex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265030.
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Sorabella, Laurie Ann. "Oyster Reef Restoration in Virginia: Broodstock Addition & Nutrient Exchanges." W&M ScholarWorks, 2002. https://scholarworks.wm.edu/etd/1539617787.
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Gabor, T. Shane (Thomas Shane). "Nutrient addition experiments in the interlake region of Manitoba : effect of single pulse addition in spring." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59941.
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This study examined the responses of algae and invertebrates to a single application of nutrients in a series of experimental wetland enclosures in the Interlake Region of Manitoba during 1989 and 1990. Water, sediment and vegetation chemistry were also monitored. The 3 fertilization treatments were: dissolved inorganic high (6200 $ mu$g/l N, 420 $ mu$g/l P), dissolved inorganic low (3200 $ mu$g/l N, 210 $ mu$g/l P) and organic high (alfalfa: 6200 $ mu$g/l N, 420 $ mu$g/l P).Dissolved nutrients in the high and low treatments were quickly depleted from the system but dissolved N increased in the alfalfa treatment as decomposition progressed. No changes in sediment or vegetation chemistry were detected. Phytoplankton biomass increased in all the fertilized enclosures while epiphytic periphyton exhibited only minor responses. Epipelon biomass increased in the alfalfa treatment and metaphyton standing crops were extensive in the high treatment enclosures.
In the alfalfa treatment, high microbial respiration rapidly decreased dissolved oxygen concentrations which negatively affected invertebrates. This trend reversed as oxygen levels increased. Dominant nektonic and benthic herbivores-detritivores increased in the high and alfalfa treatment enclosures. Orthocladiinae emergence increased in the high and alfalfa treatments while Chironominae and Tanypodinae increased in the alfalfa treatment. Responses by algae and invertebrate communities to the fertilization treatments were minimal during 1990. Annual single pulse fertilization has the potential to increase the productivity of Interlake wetlands.
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Halun, Sitti Zayda B. "The Effects of Fertilization and Simulated Grazing on the Community Structure of a Seagrass Bed in South Florida." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/415.
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The importance of resource supply and herbivory in driving competitive interactions among species has been an important but contentious issue within ecology. These variables exhibit different effects on species competition when manipulated in isolation but interact when manipulated together. I tested the direct and interactive effects of nutrient addition and simulated grazing (clipping) on the competitive performance of primary producers and community structure of a seagrass bed in South Florida. One square meter experimental plots were established in a mixed seagrass meadow from August 2007 to July 2009. The experiment was a 3 x 3 factorial experiment: 3 fertility treatments: control, medium (2.4 mg N d-1 and 80 µg P day-1) and high (4.8 mg N d-1 and 160 µg P day-1) x 3 clipping intensities (0, 25% and 50 % biomass removal (G)) x 5 replicates for each treatment = 45 plots). Nutrient additions and simulated grazing were done every two months. Fertilization and simulated grazing decreased sexual reproduction in S. filiforme. Fertilization increased competitive dominance within the primary producers while simulated grazing counteracted this effect by removal of the dominant species. Fertilization ameliorated the negative impacts of simulated grazing while simulated grazing prevented competitive exclusion in the fertilized plots. Nutrient addition and simulated grazing both exerted strong control on plant performance and community structure. Neither bottom up nor top down influences was eliminated in treatments where both factors where present. The effects of fertilization on plant performance were marked under all clipping intensities indicating that the system is regulated by nutrient availability both in the presence or absence of grazers. Clipping effects were strong under both fertilized and unfertilized conditions indicating that the seagrass bed can be simultaneously under top-down control by grazers.
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Nogueira, Carla de Almeida. "Responses and mechanisms of a mediterranean grassland ecosystem to nutrient addition." Doctoral thesis, ISA/UL, 2018. http://hdl.handle.net/10400.5/17509.
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Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaGlobal changes, resulting from anthropogenic activities, are increasing precipitation variability, drought and nutrient inputs into ecosystems. These global change drivers are expected to induce changes in grassland species richness and composition and functional structure and diversity which may in turn affect ecosystem functioning. This is particularly important for the Mediterranean basin, a climate change hotspot. Understanding how these changes affect grassland structure and functioning is critical to anticipate impacts of global change, improve management actions and develop land management strategies and restoration tools to mitigate grassland degradation. Through a pot greenhouse experiment, we applied three levels of extended autumn drought and two levels of nitrogen deposition to grassland communities. The severe drought originated a shorter growing season, and led to lower net ecosystem exchange and gross primary productivity, which translated into reduced productivity. Drought induced changes in functional group proportion and delayed plant phenology. Nitrogen addition did not affect productivity, diversity or phenology. However, nitrogen interacted with the severe drought treatment to attenuate the negative effects on total carbon fluxes. A 5-year nutrient addition field experiment was also conducted. Nitrogen, phosphorus and potassium were added in a factorial way to establish three treatments of one, two and three added nutrients, including controls. Grassland productivity was co-limited by multiple nutrients and precipitation. Nutrient addition decreased species richness and interacted with climatic variability to alter functional group composition. Resilience to disturbance was not affected by nutrient addition, as resistance that decreased with nutrient enrichment due to lower species richness was cancelled out by increased recovery due to the dominance of competitive graminoids. Community functional structure was affected by nutrient addition and precipitation and, for some traits, by their interaction and was the main determinant of productivity. Functional diversity was affected by precipitation, with drought negatively affecting community functional diversity
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Bector, Savita 1962. "Nutrient density of the infants diet after the addition of supplementary foods." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/278161.
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The recommendation of the American Academy of Pediatrics Committee on Nutrition is to delay the introduction of Supplementary foods to the infants diet until 4-6 months of age. However, it is found that supplementary foods are introduced prior to four months. In this study 48 mothers, of infants under four months of age and receiving formula and supplementary foods, were interviewed for food intake of the infant. Results from the study indicate that early introduction of supplementary foods has little influence on the total mean energy and nutrient intake. Formula was found to be the major source of energy and nutrients with only a small percentage from supplementary foods. No significant difference was found in energy and nutrient intake by ethnicity, gender of baby or age. Although the percent intake from supplementary foods increased with age. Demographics were not related to the age of introduction of supplementary foods.
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Finkler, Nícolas Reinaldo. "Dinâmica da retenção de nitrogênio e fósforo em riachos tropicais do bioma Cerrado (SP)." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-20062018-105639/.
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Os serviços ecossistêmicos se traduzem em benefícios diretos e indiretos obtidos pelos seres humanos do ambiente natural graças ao papel imprescindível dos ecossistemas para o seu bem-estar, saúde e desenvolvimento socioeconômico. Considerando o serviço ecossistêmico de purificação da água, a retenção de nitrogênio e fósforo pelos ecossistemas aquáticos depende de uma combinação de mecanismos físicos, químicos e biológicos que transformam o nutriente no sentido longitudinal de um curso de água. A retenção é majoritariamente estudada em ambientes temperados, mas ainda pouco se sabe sobre como as características ambientais de sistemas tropicais podem afetá-la. O objetivo principal dessa pesquisa foi estimar a retenção de macronutrientes em riachos localizados no bioma Cerrado (SP). Avaliaram-se, além das características físicas e químicas, as taxas de retenção de nitrato, amônio e fosfato em trechos de quatro riachos caracterizados por gradientes de concentrações ambientais para testar hipóteses vinculadas ao nível de enriquecimento por nutrientes e ao papel de riachos tropicais sobre a retenção ecossistêmica. No período de janeiro a outubro de 2017, foram realizados pulsos de nutrientes, segundo o método Tracer Additions for Spiraling Curve Characterization, para modelagem e quantificação de métricas de retenção desses nutrientes (distância, taxa e velocidade de retenção em condições ambientais), além do comportamento cinético de cada adição. Os riachos foram hierarquizados conforme o nível de enriquecimento por fosfato, variável utilizada como discriminante de tal enriquecimento em função de sua significativa variação inter-riachos. Com relação às métricas de retenção, foram encontradas diferenças espaciais significativas entre riachos, enquanto que não foram observadas diferenças temporais entre coletas. Em geral, riachos não enriquecidos apresentaram distâncias de retenção em geral menores (8-418 m para nitrato, 38-172 m para amônio e de 60-560 m para fosfato) em comparação a ambientes enriquecidos (56-508 m para nitrato, 35-253 m para amônio e de 77-391 m para fosfato). Além disso, os riachos não enriquecidos apresentaram maior velocidade de retenção (máximas de 123 mm min-1 para nitrato, 68 mm min-1 para amônio e 17 mm min-1 para fosfato), além de taxas de retenção (µg m-2 min-1) superiores em comparação aos enriquecidos. O nitrato apresentou maiores taxas ambiental de retenção (média geométrica de 999,3 µg m-2 min-1), enquanto o amônio apresentou menor distância ambiental de retenção (média geométrica de 85,7 m) e maior velocidade ambiental de retenção (média geométrica de 6,9 mm min-1). No ajuste cinético da retenção, não foi evidenciada a saturação de concentrações para nenhum caso. O modelo Efficiency-Loss mostrou melhor ajuste cinético aos dados experimentais que os modelos cinéticos de Michaelis-Menten e primeira ordem. As métricas de retenção obtidas são de magnitudes superiores às normalmente reportadas na literatura para riachos de pequeno porte em outros biomas, o que reforça a importância da preservação e conservação de riachos tropicais. Para isso, sugere-se especial atenção ao controle e disciplinamento das formas de uso e ocupação do solo nestas bacias. Concluiu-se que os riachos analisados desempenham um papel relevante como sumidouros de N e P, o que os permite colocar na categoria de cursos de água estratégicos em relação ao serviço ambiental de retenção de nutrientes. .Aquatic systems are responsible for key ecosystems services, providing direct and indirect benefits for human beings such as well-being, health and socio-economic development. The ecosystem service of water purification is one of their main functions. Nutrient uptake in surface waters is a combination of physical, chemical and biological mechanisms which transform the nutrient in a downstream direction. The nutrient uptake has been mostly studied in temperate environments, but little is known about how the environmental characteristics of tropical systems could affect it. The main objective of this study was to estimate the nutrient uptake in streams located in the Cerrado biome (SP). In addition to the physical and chemical characteristics, nitrate, ammonium and phosphate uptake rates were evaluated in reaches of four streams characterized by gradients of environmental concentrations. Also we tested hypotheses regarding the level of nutrient enrichment and the role of tropical streams on the whole ecosystem uptake. From January to October 2017, nutrient additions were carried out according to the Tracer Additions for Spiraling Curve Characterization method, in order to model and quantify nutrient uptake metrics (uptake lenght, uptake rate and uptake velocity under ambient conditions) and to characterize the kinetics of each addition. The streams were ranked according to the level of enrichment by phosphate, since its concentrations showed significant variation across streams. Significant spatial differences were found across streams, while no temporal differences were observed among sampling periods. In general, non-enriched streams generally had lower uptake lengths (8-418 m for nitrate, 38-172 m for ammonium and 60-560 m for phosphate) in comparison to enriched streams (56-508 m for nitrate, 35 -253 m for ammonium and 77-391 m for phosphate). Non-enriched streams showed higher uptake velocities (maximum of 123 mm min-1 for nitrate, 68 mm min-1 for ammonium and 17 mm min-1 for phosphate), as well as uptake rates (µg m-2 min-1) greater than enriched streams. Nitrate had higher ambient uptake rates (geometric mean of 999.3 µg m-2 min-1), while ammonium had lower ambient uptake length (geometric mean of 85.7 m) and higher ambient uptake velocity (geometric mean of 6.9 mm min-1). The uptake kinetics modelling suggested that no nutrient saturation occurred in any case. The Efficiency-Loss kinetic model had better fit to the experimental data than Michaelis-Menten and first-order kinetic models. The retention metrics obtained are higher than those normally reported in the literature for low-order streams in other biomes, which highlights the importance of preservation and conservation of tropical streams. Special attention should be given to the control and management of the land use forms in these watersheds. The studied streams play a relevant role as sinks of N and P, indicating they are strategic watercourses regarding the environmental service of nutrient uptake.
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Bock, Emily Maclauren. "Greenhouse Gas Production and Nutrient Reductions in Denitrifying Bioreactors." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/64278.
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The global nitrogen cycle has been disrupted by large anthropogenic inputs of reactive nitrogen to the environment. Excess nitrogen underlies environmental problems such as eutrophication, and can negatively affect human health. Managing the natural microbial process of denitrification is advocated as a promising avenue to reduce excess nitrogen, and denitrifying bioreactors (DNBRs) are an emerging technology harnessing this biochemical process. Previous DNBR research has established successful nitrate removal, whereas this study examines the potential to expand DNBR functionality to address excess phosphorus and mitigate the production of nitrous oxide, a potent greenhouse gas.
Results from a laboratory experiment supported the hypothesis that the addition of biochar, a charcoal-like soil amendment and novel organic carbon source in DNBR research, would increase nitrate and phosphorus removal as well as decrease the accumulation of nitrous oxide, an intermediate product of microbial denitrification.
In order more closely examine the ratio of the products nitrous oxide and inert dinitrogen, development of a novel analytical method to quantify dissolved gases in environmental water samples using gas chromatography mass spectrometry was undertaken. Although static headspace analysis is a common technique for quantifying dissolved volatiles, the variation in sample preparation has recently been revealed to affect the determination of dissolved concentrations of permanent gases and convolute comparison between studies. This work demonstrates the viability of internal calibration with gaseous standard addition to make dissolved gas analysis more robust to variable sample processing and to correct for matrix effects on gas partitioning that may occur in environmental samples.Master of Science
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Bock, Emily. "Greenhouse Gas Production and Nutrient Reductions in Denitrifying Bioreactors." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/64278.
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The global nitrogen cycle has been disrupted by large anthropogenic inputs of reactive nitrogen to the environment. Excess nitrogen underlies environmental problems such as eutrophication, and can negatively affect human health. Managing the natural microbial process of denitrification is advocated as a promising avenue to reduce excess nitrogen, and denitrifying bioreactors (DNBRs) are an emerging technology harnessing this biochemical process. Previous DNBR research has established successful nitrate removal, whereas this study examines the potential to expand DNBR functionality to address excess phosphorus and mitigate the production of nitrous oxide, a potent greenhouse gas.
Results from a laboratory experiment supported the hypothesis that the addition of biochar, a charcoal-like soil amendment and novel organic carbon source in DNBR research, would increase nitrate and phosphorus removal as well as decrease the accumulation of nitrous oxide, an intermediate product of microbial denitrification.
In order more closely examine the ratio of the products nitrous oxide and inert dinitrogen, development of a novel analytical method to quantify dissolved gases in environmental water samples using gas chromatography mass spectrometry was undertaken. Although static headspace analysis is a common technique for quantifying dissolved volatiles, the variation in sample preparation has recently been revealed to affect the determination of dissolved concentrations of permanent gases and convolute comparison between studies. This work demonstrates the viability of internal calibration with gaseous standard addition to make dissolved gas analysis more robust to variable sample processing and to correct for matrix effects on gas partitioning that may occur in environmental samples.Master of Science
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Cloutier, Renée R. "Effects of nutrient addition mode on jack pine, Pinus banksiana Lamb., seedling outplanting performance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/MQ31420.pdf.
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Richardson, Sarah Jane. "Response of a sub-Arctic dwarf shrub heath community to nutrient addition and warming." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251133.
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Beck, Michael. "THE EFFECT OF CHRONIC NUTRIENT ADDITION FROM WASTEWATER ON FOREST ECOSYSTEMS AT THE RICE RIVERS CENTER." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5164.
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Wastewater application to land can be a useful tool for mitigating impacts of nutrient enrichment on aquatic systems. A land application treatment system at VCU’s Rice Rivers Center in Charles City County, VA provided an opportunity to study the impact of wastewater addition on the biogeochemistry of forests representative of the Mid-Atlantic Coastal Plain. Nutrient concentrations in throughfall and leachate were measured at Treatment and Control sites to assess differences in nutrient deposition and retention. Wastewater amended plots from the Walter L. Rice education building received 20-fold (N) and 6-fold (P) higher inputs relative to Control plots and plots located at the Virginia Department of Game and Inland Fisheries building. Despite higher inputs, leaching losses of P from the Rice Treatment plots were comparable to Control plots, indicating that the land-based application system effectively mitigated wastewater loads. Leaching losses of nitrate were two-fold higher from Treatment plots relative to Controls, suggesting a potential N saturation effect and a reduction in N retention capacity of the treated forest. Nitrogen effects on vegetation were indicated by lower root biomass and greater root N content among Treatment plots relative to Control plots. Overall, these results suggest that wastewater–amended plots near the Rice education building receive appreciably higher nutrient inputs and could, therefore, serve as a model system for assessing effects on forest ecosystems.
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Williams, Rachel. "Effectiveness of Biochar Addition in Reducing Concentrations of Selected Nutrients and Bacteria in Runoff." UKnowledge, 2016. http://uknowledge.uky.edu/bae_etds/40.
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Land application and storage of horse manure and municipal sludge can increase nutrient and bacteria concentrations in runoff. Biochar increases soil nutrient retention when used as a soil amendment. The objectives of this study were to determine if biochar, when mixed with horse manure or sludge, affects runoff concentrations of total Kjehldahl nitrogen (TKN), ammonia-nitrogen (NH3-N), nitrate (NO3-N), total phosphorus (TP), dissolved phosphorus (DP), total suspended solids (TSS), chemical oxygen demand (COD), and fecal coliforms (FC). Horse manure and sludge were applied to 2.4 x 6.1 m fescue plots (six each), with three plots of each material amended with 5-8% biochar w/w. Simulated rainfall (101.6 mm/h) was applied to the 12 treatment plots and three control plots. The first 0.5 h of runoff was collected and analyzed for the above-listed parameters. The data were analyzed using an ANCOVA, with SCS runoff curve number (CN) used as the covariate. In general, CN was directly correlated to runoff concentrations of parameters. Plots with low CN values displayed no treatment differences for any measured parameter. Biochar reduced runoff concentrations of TKN and NH3-N for municipal sludge treatments, and TKN, NH3-N, TP, TSS, and FC for horse manure treatments.
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Wiese, Benjamin. "Control and Modeling of Plant Growth : A versatile system for mineral nutrient addition and feed-back monitoring." Thesis, KTH, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104617.
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Studying plants under controlled environmental conditions is a key component of current research. This thesis concentrates on the study of plant growth under nutrient-limiting conditions. The first objective is the design and construction of a prototype of a system which is able to supply nutrient solutions of prescribed time-dependent concentration to laboratory plants. The system, once configured via a PC, operates fully automatically without the need for human interference. The hardware setup is made of basic electric components, solenoid pinch valves, mixing pumps and metering pumps while the software is implemented in NI LabVIEW. In addition a dynamic model of plant growth is deployed for investigating possible influence on growth with help of the designed system. The focus hereby lies on investigating effects on RGR and steady-state growth during the exponential phase of plant growth.
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Wilson, Daniel T. "Grass invasion in urban lowland fynbos fragments on the Cape Flats : does nutrient addition play a role?" Bachelor's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/25608.
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Invasion by exotic grasses is a major threat to natural ecosystems in many parts of the world. On the Cape Flats in Cape Town, grasses were observed to be invading lowland fynbos fragments which are a high priority for conservation. The observation in other parts of the world that nutrient additions from deposition of airborne pollutants were responsible for increased dominance of grass in natural ecosystems led us to test whether this was the case on the Cape flats. Phytometers were used to gauge the favourability for growth of soils from urban sites compared to those from rural control sites. An attempt was also made to demonstrate the negative effects of grass invasion on seedling establishment and diversity of native species by removal of grass cover and addition of smoke water. Phytometer results were inconclusive, but soil from city sites generally had higher total N than control sites for comparable amounts of organic matter, suggesting that N addition may be occurring. Total seedling emergence was significantly increased by removal of grass cover (p<0.001) and smoke water addition (p<0.05). The implications of our results for conservation of urban fynbos fragments are discussed and further, more detailed investigation of this topic is recommended.
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REIS, ROGERIO A. de S. "Caracterização de componentes inorgânicos em suplementos nutricionais pelo método de análise por ativação com nêutrons." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11401.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Lindberg, Niklas. "Impact of climate change on soil fauna diversity : effects of experimental drought, irrigation, soil warming and nutrient addition /." Uppsala : Swedish Univ. of Agricultural Sciences, 2001. http://epsilon.slu.se/avh/2001/99-3576673-X.pdf.
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Weeber, Russell C. "Nutrient addition and the use of stable isotope techniques in wetlands of the Interlake Region of Manitoba, Canada." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22825.
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This study examines the relationship between nutrient additions and algae and invertebrate productivity in a nutrient-poor wetland of the Interlake Region of Manitoba, Canada. Alfalfa hay was added to experimental enclosures in May 1992. Alfalfa additions were made in unprocessed and ground forms and consisted of three treatments: ground low, whole low, and whole high. Dissolved oxygen, surface water nutrients, algae standing crop, and invertebrate production were monitored at open marsh sites and in treatment and control enclosures during 1992 and 1993. Stable $ sp{13}$C, $ sp{15}$N and $ sp{34}$S isotope ratios were determined for the alfalfa additions, and for surface water, algae, macrophytes, sediments and invertebrates.In general, the effects of nutrient additions were confined to 1992. Treatment enclosure dissolved oxygen levels decreased immediately following fertilization, recovering in the low treatments by early June. Low oxygen conditions persisted in whole high enclosures throughout most of 1992. Dissolved and suspended nutrient concentrations, and phytoplankton chlorophyll a increased but, with the exception of dissolved N, were soon lost from the water column. Treatment enclosure epiphytic algae increased while epipelon did not respond to fertilization. The primary effect of fertilization on invertebrate production was an increase in treatment enclosure chironomid larvae during 1992. As with productivity measures, stable isotope ratio values suggested a temporary presence of alfalfa nutrients in the enclosed food webs. Only the isotope ratios of metaphytic algae and snails collected during August 1992 indicated an incorporation of alfalfa nutrients.
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Wotherspoon, Katherine. "The effect of phosphorus addition and cutting date on the nutrient dynamics and species composition of floodplain meadows." Thesis, Open University, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.757703.
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Cubas, Suazo Alexa Maria. "Occoquan Reservoir and Watershed: A Water Quality Assessment 1973–2019." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103037.
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The Occoquan Reservoir is part of the largest indirect potable reuse systems in the United States. It in an important water supply source for the Northern Virginia area, as well as, an ecological and recreational area. Furthermore, the Occoquan Reservoir protects the water quality of the Chesapeake Bay because it acts as a trap for sediments and pollutants. Continuous water quality monitoring and evaluation is critical to preserve this important water resource. Reservoir water quality can be affected by the delivery of pollutants from point and nonpoint sources, potentially causing problems such as eutrophication, excess salinization, presence of compounds that affect human and aquatic health. Different management strategies have been implemented at the Occoquan Reservoir to nutrient loading into the reservoir and address eutrophication issues, including nitrate addition to hypolimnetic waters and installation of a hypolimnetic oxygenation system. The goal of this study is to assess how current management strategies implemented in the Occoquan Reservoir have affected the water quality from 1973 to 2019, with particular emphasis on the data since 2003. This analysis of the Occoquan Reservoir and its tributary watershed includes the evaluation of hydrometeorological data and morphometric characteristics; establishment of long-term trends for water quality constituents; and determination of the trophic state of the reservoir. Data from water samples from four different stations located at the Occoquan Reservoir and four stations located throughout the Occoquan tributary watershed were analyzed for nutrients, principal ions and metals, synthetic organic compounds (SOCs), and other water quality parameters. Long-term water quality trends were determined using Mann-Kendall test and relationship between constituents was evaluated using Principal Component Analysis (PCA). Trophic state of the reservoir was assessed using Carlson's Trophic State Index (TSI), Vollenweider Model, and Rast, Jones, and Lee's Model. Results indicate the Occoquan Reservoir is a eutrophic waterbody. However, the nitrate management strategy and the installation of the hypolimnetic system have improved reservoir water quality, reducing concentrations of nutrients and metals.Master of Science
The Occoquan Reservoir is part of the largest indirect potable reuse systems in the United States. Indirect potable reuse refers to the planned discharge of reclaimed water into a water supply source, such as a reservoir or lake. The Occoquan Reservoir also serves as an ecological and recreational area, and serves to protects the water quality of the Chesapeake Bay because it acts as a trap for sediments and pollutants. To protect the different ecosystem services that the reservoir provides, it is critical to continuously monitoring and evaluate its water quality. Reservoir water quality can be affected by the delivery of pollutants from industrial and municipal waste discharges (point sources), as well as, from urban and agricultural runoff (nonpoint sources). Contaminants include nutrients (such as nitrogen and phosphorus), ions, metals, and synthetic organic compounds (SOCs) that can affect human and aquatic health. Different management strategies have been implemented at the Occoquan Reservoir to reduce load of pollutants into the reservoir, particularly to reduce concentrations of nutrients, as excessive nutrients can degrade water quality. Two strategies implemented are the addition of nitrogen, in the form of nitrate, and the installation of an oxygenation system at the reservoir bottom waters. The goal of this study is to assess how current management strategies implemented in the Occoquan Reservoir have affected the water quality from 1973 to 2019, with particular emphasis on the data since 2003. This analysis of the Occoquan Reservoir and its tributary watershed includes the evaluation of the hydrological, meteorological, and morphometric characteristics of the Occoquan Reservoir and Watershed; establishment of long-term trends for water quality constituents; and determination of the productivity (trophic state) of the reservoir. Data from water samples from four different stations located at the reservoir and four stations located throughout the watershed were analyzed for nutrients, principal ions and metals, SOCs, and other water parameters indicative of water quality. Statistical analyses were employed to determine long-term water quality trends (Mann-Kendall test) and relationship between constituents (Principal Component Analysis - PCA). The trophic state of the reservoir was assessed using three methods: Carlson's Trophic State Index (TSI), Vollenweider Model, and Rast, Jones, and Lee's Model. Results indicate the Occoquan Reservoir is eutrophic, or highly enriched with nutrients and productive. However, management strategies employed have improved the water quality and the reservoir continues to improve, though at a slow rate.
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Welch, Anthony Richard. "The effect of anthropogenic nutrient addition on the growth and competitive abilities of Parmelia caperata, P. reddenda, P. saxatilis and Xanthoria parietina in Cornwall." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289005.
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Dornelas, Lívia Carrasco. "Efeito da temperatura ambiente e suplementação da dieta com protease no desempenho e utilização de nutrientes em frangos de corte." Botucatu, 2017. http://hdl.handle.net/11449/151444.
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Orientador: José Roberto SartoriResumo: Avaliou-se o efeito da suplementação de protease na digestibilidade e desempenho de frangos de corte em ambiente termoneutro e estresse cíclico pelo calor. Foram utilizados 320 pintos machos Cobb de um dia distribuídos casualmente em esquema fatorial 2x2x2 [ambiente termoneutro ou ambiente quente x dieta atendendo as exigências nutricionais (controle positivo, CP) ou reduzida 6% em proteína bruta e aminoácidos (controle negativo, CN) x protease: 0 ou 200ppm] com 8 repetições. De 1 a 7 dias de idade, a conversão alimentar (CA) foi melhor em frangos CN quando em ambiente termoneutro, e quando em ambiente quente, a CA melhorou com a dieta CP. Frangos em ambiente termoneutro apresentaram melhor CA e maior ganho de peso no período de 1 a 14 dias. Maior consumo de ração e ganho de peso foram observados em frangos mantidos em ambiente termoneutro nos períodos de 1 a 21 dias e 1 a 35 dias de idade. No período de 1 a 35 dias de idade houve interação entre dieta e protease, sendo que frangos que receberam dietas CP apresentaram melhor CA quando receberam protease. Frangos que receberam protease melhoraram a conversão alimentar quando consumiram CP comparados aos que receberam CN. A suplementação de protease favoreceu balanço de nitrogênio, coeficiente de metabolizabilidade da proteína bruta e da matéria seca e a energia metabolizável aparente e energia metabolizável aparente corrigida pelo nitrogênio em frangos de corte em ambiente quente com dieta controle positivo. Concluindo, o estr... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objective of the current study was to evaluate the effects of protease supplementation on diet digestibility and growth performance of broilers raised under thermoneutral condition and cyclic heat stress. In a 2x2x2 factorial system [thermoneutral condition or heat stress vs. diets formulated to meet nutritional (positive control, PC) or diets with crude protein and amino acids below requirements by 6% (negative control, NC) x Protease: 0.200ppm], 320 one-day-old male Cobb broilers were distributed in 8 replicates. From 1 to 7 days of age, feed conversion ratio (FCR) was better in thermoneutral condition, and in heat stress, feed conversion ratio (FCR) was better when consume PC. Broilers in thermoneutral environment presented best FCR and greater weight gain during the period from 1 to 14 days. Increased feed consumption and weight gain were observed in broilers kept in thermoneutral environment in periods of 1 to 21 days and 1 to 35 days old. During the period from 1 to 35 days of age there was interaction between diet and protease, and broilers that were given diets CP presented best FCR when they received protease. Broilers receiving protease improved feed conversion when consumed PC compared to those receiving NC. Protease supplementation favored nitrogen balance, metabolizable crude protein, dry matter, apparent metabolizable energy and nitrogen-corrected apparent metabolizable energy in broiler chickens in heat stress with positive control diet. In conclusion, heat... (Complete abstract click electronic access below)
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Loures, Daniele Rebouças Santana. "Enzimas fibrolíticas e emurchecimento no controle de perdas da ensilagem e na digestão de nutrientes em bovinos alimentados com rações contendo silagem de capim Tanzânia." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-16072004-155623/.
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Este trabalho teve por objetivo avaliar o efeito de enzimas fibrolíticas na degradação da parede celular do volumoso, quando aplicadas antes da ensilagem e no momento da alimentação do animal. No experimento I analisou-se o efeito do emurchecimento, da redução do tamanho de partículas e da adição de enzimas fibrolíticas (associadas ou não ao inoculante bacteriano Lactobacillus plantarum) na fermentação e nas perdas do processo de ensilagem de capim Tanzânia (Panicum maximum, Jacq. cv. Tanzânia). A forragem foi cortada aos 45 dias de crescimento vegetativo e armazenada em silos experimentais (50 L) durante 136 dias. Durante o período de armazenamento o efluente foi coletado e quantificado no 1o, 2o, 7o, 14o, 21o, 60o, 90o e 136o dias. A redução do tamanho de partícula não influenciou as perdas totais, embora o tamanho menor tenha contribuído para garantir maior estabilidade aeróbia da silagem. A taxa de recuperação e as perdas de MS por efluente e gases foram de 72, 5 e 23% nas silagens não-emurchecidas e de 80, 0 e 21% nas silagens emurchecidas, respectivamente. A adição de enzimas fibrolíticas associadas ou não ao inoculante bacteriano promoveu redução da fração fibrosa (FDN, FDA, celulose, hemicelulose), sendo esta redução mais acentuada nas silagens emurchecidas. Contudo, não houve aumento da digestibilidade in vitro da MS com adição de enzimas fibrolíticas. Foram observados os valores médios de DBO (11.289 mg L 1), DQO (36.279 mg L 1) e DQO/DBO (3,35) no efluente das silagens contendo umidade original; o maior período de armazenamento aumentou significativamente o potencial poluidor do efluente. O experimento II teve por objetivo avaliar o efeito do conteúdo de matéria seca da forragem e o uso de enzimas fibrolíticas aplicadas durante a ensilagem de capim Tanzânia ou após a abertura do silo. Os tratamentos foram confeccionados da seguinte forma: A - forragem emurchecida sem aplicação de enzimas; B não-emurchecida sem aplicação de enzimas; C - emurchecida com enzimas (2 L t -1 de massa verde); D não-emurchecida com enzimas; e E não-emurchecida com enzimas (10 L t -1 de massa verde), após a abertura do silo. Cinco novilhos da raça Nelore foram distribuídos ao acaso em delineamento do tipo Quadrado Latino 5 x 5. Os parâmetros de cinética de passagem de sólidos (2,23% hora-1) e de líquidos (4,83% hora-1) foram similares para os tratamentos avaliados. O comportamento ingestivo dos animais não foi alterado com a elevação da concentração de MS da silagem, sendo observados os seguintes tempos (minutos dia-1) e taxas (min kg MSI-1) de ingestão de MS (247 e 24), de ruminação (426 e 43) e de mastigação (673 e 67), respectivamente. As médias das concentrações totais dos ácidos graxos voláteis (109,62 mM) e de nitrogênio amoniacal (5,6 mg dL-1), do fluido ruminal, não foram alteradas pelos tratamentos aplicados. Diante dessas observações, pode-se concluir que o emurchecimento da forragem e o uso de aditivo enzimático não resultaram em alterações significativas no comportamento ingestivo, nos parâmetros ruminais e na digestibilidade de nutrientes em animais.The present trial aimed to evaluate the effect of fibrolytic enzymes on forage cell wall degradation, when applied either during the ensiling process or just before the animal feeding. The experiment I analyzed the effects of wilting (wet vs wilted), particle size reduction (small vs large) and the addition of fibrolytic enzymes (alone vs combined with Lactobacillus plantarum) on the fermentation and ensiling losses of Tanzania grass (Panicum maximum, Jacq. cv. Tanzania). Forage was harvested and cut at 45-day vegetative re-growth period and stored in experimental plastic silos (50 L) during 136 days. During the storage period, the effluent flow was collected and measured at days 1, 2, 7, 14, 21, 60, 90 and 136. Total silage losses were not affected by particle size reduction, even though the smallest particle size promoted better aerobic stability of the silage. The rate of silage DM recovery, effluent and gases losses were 72, 5 e 23 % for wet and 80, 0 e 21% for wilted silages, respectively. The addition of fibrolytic enzymes exclusively or combined with Lactobacillus plantarum led to decreased concentrations of NDF, ADF, cellulose and hemicellulose mainly on wilted silages, however, no benefit was observed in the in vitro DM digestibility. Mean values for BOD (11.289 mg L 1), COD (36.279 mg L 1), and the ratio COD/BOD (3.35) were observed on the effluent of wet silages, which increased the potential of environmental pollution with the longer silage storage period. The experiment II aimed to study the effects of forage wilting or fibrolytic enzymes addition to the Tanzania grass silages. Treatments consisted of: A - wilted forage without enzymes; B - fresh forage without enzymes; C - wilted forage with enzymes at ensiling (2 L t-1 wet forage); D - fresh forage with enzymes at ensiling; E - enzymes applied onto silage (10 L t-1 wet silage) 30 minutes before feeding (direct-fed). Five ruminally cannulated Nellore beef steers were randomly assigned to a 5 x 5 Latin square design. The ruminal passage rate of solid (2.23 % hour 1) and liquid (4.83 % hour 1) phases were similar for all treatments. The animal ingestive behavior measured as total time (minutes day-1) and rate (minutes DM kg-1) was not changed across silages DM concentration, averaging DM eating (247; 24), DM ruminating (426; 43) and DM chewing (673; 67), respectively. The molar concentration (109.62 mM) of total volatile fatty acids (VFA) and ammonia-N (5.6 mg dL-1) observed in ruminal fluid were similar across silages diets. According to the results it may be concluded that wilting Tanzania grass or the application of fibrolytic enzymes did not improve significantly either the animal ingestive behavior, ruminal parameters or the nutrient digestibilty.
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Coelho, Rodrigo Michelini. "Efeitos da concentração de matéria seca e do uso de inoculante bacteriano-enzimático, na silagem de tifton 85 (Cynodon spp.), sobre a digestão de nutrientes, parâmetros ruminais e comportamento ingestivo em novilhos de corte em crescimento." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-19122002-163719/.
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O presente trabalho teve como objetivo avaliar o efeito do emurchecimento da forragem associado ou não ao uso do aditivo bacteriano-enzimático na ensilagem do capim Tifton 85 (Cynodon spp.). Foi realizada avaliação de perdas nos painéis das silagens experimentais, assim como da composição bromatológica e do tamanho de partículas das mesmas. Ocorreram observações periódicas de comportamento ingestivo, consistência ruminal, consumo voluntário, parâmetros de fermentação ruminal, digestibilidade dos nutrientes, taxa de passagem de sólidos e líquidos ruminais em novilhos que receberam rações contendo 80% desses volumosos na base seca. Foram utilizados sete novilhos da raça Nelore, distribuídos ao acaso em um experimento do tipo quadrado latino 7 x 7. Os tratamentos avaliados foram resultantes da combinação de 3 concentrações de matéria seca (MS) na silagem do capim Tifton 85 (25, 45 e 65%) associadas (CA) ou não (SA) ao aditivo bacteriano-enzimático. Um tratamento adicional contendo 55% MS sem aditivo também foi avaliado. O aditivo utilizado foi o produto comercial SILALL®, contendo cepas de Streptococcus faecium, Lactobacillus plantarum, Pediococcus acidilactici e as enzimas hemicelulase, celulase e amilase, aplicadas na dosagem de 250 g de SILALL® diluídas em 50 litros de água por tonelada de forragem, imediatamente antes da ensilagem. A técnica de emurchecimento possibilitou elevar o teor de matéria seca mas, da mesma maneira que a adição do inoculante bacteriano-enzimático, provocou alterações pouco pronunciadas na composição química da silagem. Nas silagens SA o aumento da concentração de MS foi acompanhado de elevação no teor de FDN resultando em redução do teor de carboidratos não fibrosos (CNF). A fração protéica B3 nas silagens apresentou tendência de aumento com a elevação na concentração de MS, em função da progressiva elevação da fração N insolúvel no FDN, simultaneamente à redução N insolúvel no FDA. A avaliação dos silos após abertura, indicou aumento de perdas com a elevação da concentração de MS que, entretanto, podem ter sido decorrentes de uma menor taxa de utilização dos fardos contendo silagens com menor umidade. Tanto a consistência ruminal, avaliada como o tempo de ascensão do pêndulo no interior do rúmen (1194 seg.), como os parâmetros de cinética de passagem de sólidos (3,09% hora -1 ) e de líquidos (4,37% hora -1 ) foram similares para os tratamentos avaliados. O comportamento ingestivo dos animais não foi alterado com a elevação da concentração de MS da silagem, sendo observados tempos (minutos dia -1 ) e taxas (min kg MS 1 ) de ingestão de MS (324; 47), ruminação (518; 75) e mastigação (841; 123), respectivamente. O consumo diário de MS das rações, pelos animais, foi semelhante para os tratamentos avaliados, resultando em média de 6,95 kg equivalente a 1,88% do peso corpóreo. As concentrações molares (mM) individuais e totais (140,29) dos ácidos graxos voláteis, a relação acetato:propionato (4,2:1), concentração de nitrogênio amoniacal (6,31 mg dL -1 ) e o pH (6,76), do fluido ruminal, não foram alterados pelos tratamentos estudados. As digestibilidades da matéria orgânica (71,5%), proteína bruta (69,1%), FDN (71,3%), FDA (64,9%) e hemicelulose (83,3%) não foram, em geral, fortemente influenciadas pela concentração de MS da silagem do capim Tifton 85, aditivadas ou não. No entanto, a digestibilidade da MS (71,0%) apresentou um comportamento quadrático (P<0,05), com ligeira elevação ao redor de 45% de concentração de MS, nas silagens. Diante destas observações, pode-se concluir que o emurchecimento da forragem e o uso de aditivo bacteriano-enzimático não resultaram em alterações expressivas nos parâmetros ruminais, digestivos e no comportamento ingestivo dos animais.The present trial aimed to study the effects of forage wilting associated or not with a bacterial-enzymatic inoculant on ensiling Tifton 85 grass. Front panel of experimental silos (325 kg square wrapped bales) were daily scored for fungi development and weekly sampled for chemical composition analysis and particle chop length measurements. In a randomized 7 x 7 Latin square design, seven ruminal cannulated growing beef steers were assigned to diets (treatments) containing 80% silage. Periodically chewing behavior, feed intake, ruminal mat consistency, ruminal fermentation parameters, nutrient digestibility and ruminal rate of passage of solids and liquids phases were evaluated. Treatments combined 3 planned dry matter (DM) concentrations (25, 45 and 65%) of Tifton 85 grass silage associated (CA) or not (SA) with the bacterial-enzymatic (BE) inoculant source. An additional treatment containing wilted silage (55% DM) without (BE) was also studied. SIL-ALL®, the BE source used, was sprayed onto chopped forage just before silage packing at a rate of 250g diluted in 50L of deionized water per ton of wet forage. The commercial BE showed the following composition: Streptococus faecium, Lactobacillus plantarum, Pediococcus acidilactici plus hemicellulase, cellulase and starch degrading enzymes. The wilting of forage allowed to increase the DM concentration of silages, however, as well as BE addition, it was not effective to promote major changes on chemical composition of silages. On SA silages, higher NDF levels were observed as the DM level of the wilted silage increased, which resulted in lower non-fiber carbohydrate (NFC) fraction. The B3 protein fraction (NDIN minus ADIN) showed an increase as the DM concentration of wilted silage was raised, probably as result of an opposite trend between neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) across DM levels. Silage losses, measured as both, fungi scored at bale front panel and percentage of spoiled silage, indicated higher levels associated with increased DM concentration. It might be explained by the lower bale unloading rate observed during the feeding trial, mainly in higher DM wilted silages. Both, ruminal mat consistency, measured as time required to weight ascension into the rumen (1194 sec.) as well as ruminal kinetics, evaluated as passage rate of solid (3.09% hour -1 ) and liquid (4.37% hour -1 ) phases were similar for all treatments. Animal ingestive behavior measured as total time (minutes day -1 ) and rate (minutes DM kg -1 ) was not changed across silages DM concentration, averaging DM eating (324; 47), DM ruminating (518; 75) and DM chewing (841; 123), respectively. Residual daily time was spent with drinking and idling activities. The DM intakes observed among experimental diets, containing wilted silages, were not statistically different and averaged 6.95 kg day -1 or 1.88% as body weight basis. Individual and total (140.29) molar concentration (mM) of volatile fatty acids (VFA), acetate:propionate ratio (4,2:1), ammonia-N (6.31 mg dL -1 ) and average daily pH (6.76) of ruminal fluid were similar across silages diets. Nutrient digestibilities were, also, not significantly affected by the increased DM concentration in wilted silages or by the BE inoculation, as follows: organic matter (71.5%), crude protein (69.1%), NDF (71.3%), ADF (64.9%) and hemicellulose (83.3%). DM digestibilities, however, performed a quadratic pattern (P<0.05), with a slight increase at 45% DM concentration in silages. According to the results it may be concluded that neither the increase of DM concentration of grass silages nor the addition of bacterial-enzymatic inoculant changed animal ingestive behavior or improved ruminal and digestive parameters analyzed.
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Dalmet, Christophe. "La notion de denrées alimentaires." Phd thesis, Université d'Avignon, 2009. http://tel.archives-ouvertes.fr/tel-00629627.
Full textAbstract:
Avec l'apparition massive des borderline products, les frontières traditionnelles entre la denrée alimentaire et les autres catégories de produits que l'on ingère ne cessent de se brouiller. Certes des éléments de définition de cette denrée se trouvent dans divers textes juridiques, notamment communautaires à l'image du règlement Food Law, mais toujours est-il que malgré tout demeure en partie le mystère identitaire qui entoure cette notion. Aussi, afin de pouvoir appliquer aux produits litigieux un statut adéquat et déterminer par la même le régime juridique qui doit être le leur, des références précises de l'aliment doivent être mises en évidence au travers de son analyse d'ensemble, l'étude tant de sa fonction que de sa présentation s'avérant indispensable pour résoudre cette problématique non dépourvue d'importance pratique.
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Rulon, Leslie. "Effects of Nutrient Additions on Three Coastal Salt Marsh Plants Found in Sunset Cove, Texas." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8798.
Full textAbstract:
Eutrophication, particularly due to nitrogen (N) and phosphorus (P) input, has been massively altered by anthropogenic activities. Thus it is important to understand the impact on salt marsh plants; however studies on salt marsh plants within Galveston Bay, Texas are limited. In this study, the effects of repeated nutrient additions in monospecific plots of Spartina alterniflora, Batis maritima¸ and Salicornia virginica as well as mixed plots of B. maritima and S. virginica were studied over 15 months. Results showed that nutrient loading led to an increase in height, biomass, growth rate and percent nitrogen (N) within all three species studied, but were species specific more than dose dependent. Nitrogen content in leaves had a positive correlation with P content in leaves but a negative correlation with carbon (C) content. Nutrient loading lead to a significant increase in total chlorophyll in the fertilized plots of S. alterniflora and S. virginica one month into the study. Nutrient addition to two succulent species, B. maritima and S. virginica in mixed plots did not reveal a distinct superior competitor within the 15 month study in terms of growth and nutrient use efficiencies; however using the maximum growth rates of the monospecific plots, the Monod model was used to determine which species would dominate at high nutrient loads. Based on height data S. alterniflora would dominate, while B. maritima would dominate according to the Monod model based on biomass.
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"The effects of nutrient additions on the sedimentation of surface water contaminants in a uranium mined pit-lake." Thesis, 2005. http://hdl.handle.net/10388/etd-05282012-111234.
Full textAbstract:
I investigated the usefulness of phytoplankton for the removal of surface water
contaminants. Three experiments, consisting of nine large mesocosms (92.2 m3) were
suspended in the flooded DJX uranium pit at Cluff Lake (Saskatchewan, Canada), and
filled with contaminated mine water. During the summer of 2003, each mesocosm was
fertilized with a different amount of phosphorus throughout the 35 day experiment to
stimulate phytoplankton growth, and to create a range in phosphorus load (g) to examine
how contaminants may be affected by different nutrient regimes. Algal growth was
rapid in fertilized mesocosms as demonstrated by chlorophyll a profiles. As phosphorus
loads increased there were significant declines in the surface water concentrations of As,
Co, Cu, Mn, Ni, and Zn. This decline was near significant for uranium. The surface
water concentrations of Ra226, Mo, and Se showed no relationship to phosphorus load.
Contaminant concentrations in sediment traps suspended at the bottom of each
mesocosm generally showed the opposite trend to that observed in the surface water,
with most contaminants (As, Co, Cu, Mn, Ni, Ra226, U, and Zn) exhibiting a significant positive relationship (P < 0.05) with phosphorus load. Sediment trap concentration of Se
and Mo did not respond to nutrient treatments.
Similar experiments were repeated during the mid- and late-summer of 2004,
with 5 mesocosms being fertilized with phosphorus, and another 4 with both phosphorus
and ammonium to create different nutrient gradients. Results from these experiments
were much more variable than those seen in the experiment conducted in 2003, and small samples (n = 5 for phosphorus treatments and n = 4 for both phosphorus and
ammonium treatments) yielded insufficient statistical power to effectively determine
statistically significant trends. However, contaminant sedimentation tended to respond to
phosphorus treatments in a similar manner as results from 2003; phosphorus-with-ammonium
treatments had little positive effect on contaminant sedimentation rates.
My results suggest that phytoremediation has the potential to lower many surface
water contaminants through the sedimentation of phytoplankton. Based on our results
from 2003, we estimate that the Saskatchewan Surface Water Quality Objectives
(SSWQO) for the DJX pit would be met in approximately 45 weeks for Co, 65 weeks
for Ni, 15 weeks for U, and 5 weeks for Zn if treated using phytoremediation.Note:Appendix A content (pages 92-95) contains copyrighted material which has been removed. It can be viewed in the original thesis upon request.
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Matson, Amanda. "Canopy soil nutrient cycling and response to elevated nutrient levels along an elevation gradient of tropical montane forests." Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5E97-C.
Full textAbstract:
Obwohl Böden des Kronendachs (canopy soils) deutlich zur oberiridischen labilen Biomasse beitragen können, werden sie oft in Studien über Nährstoffkreisläufe übersehen. In Wäldern mit einem großen Vorkommen an Böden im Kronendach, wie beispielsweise jene in tropischen Bergregionen, könnte dies zu einem unvollständigen Verständnis der Gesamt-Nährstoffprozesse des Waldes beitragen. Böden im Kronendach sind Ansammlungen organischen Materials, welche gewöhnlich auf Zweigen von Bäumen tropischer Wälder zu finden sind. Sie bestehen in erster Linie aus zersetztem epiphytischen Material aber umfassen auch herunterfallendes Laub, Staub, wirbellose Tiere, Pilze und Mikroorganismen. Es gibt nur eine Handvoll Studien, die Stickstoff (N) Kreisläufe und/oder Treibhausgas (THG) Flüsse in Böden des Kronendachs untersucht haben und keine hat versucht die tatsächlichen Feldraten zu bestimmen oder herauszufinden, wie sich diese Böden – welche besonders sensibel gegenüber atmosphärischen Prozessen sind – mit Nährstoffdeposition ändern könnten. Diese Dissertation stellt die Ergebnisse einer Forschungsstudie dar, welche N-Umsatzraten und THG Flüsse von Böden des Kronendachs quantifiziert und untersucht, wie diese Raten durch zunehmende Mengen an N und Phosphor (P) im Boden verändert werden.
In Gebieten mit atmosphärischer N- und P-Deposition, erhalten Böden des Kronendaches sowohl direkte als auch indirekte Nährstoffeinträge auf Grund von angereichertem Bestandsniederschlag und Pflanzenstreu. Es wurden folgende Umsatzraten in Böden des Kronendachs tropische Bergwälder entlang eines Höhengradienten (1000 m , 2000 m , 3000 m) gemessen: (1) asymbiotische biologische N2-Fixierung, (2) Netto- und Brutto-N-Transformation, und (3) Kohlendioxid (CO2), Methan (CH4) und Lachgas (N2O) Flüsse. Zudem wurden indirekte Auswirkungen von N-und P-Gaben, die auf dem Waldboden ausgebracht wurden, untersucht. Umsatzraten der N2-Fixierung, des N Kreislaufes und von THG Flüssen, welche in Böden des Kronendachs gemessen wurden, wurden mit denen vom Waldboden verglichen (entweder als Teil dieser Arbeit oder in parallelen Studien von zwei anderen Mitgliedern unserer Arbeitsgruppe), um die Aktivität von Böden des Kronendachs in den Kontext des gesamten Waldes zu stellen. N2-Fixierung wurde mit der Acetylenreduktionsmethode, Netto-N-Umsatzraten wurden mittels in situ Inkubationen (buried bag method) und Brutto-N-Umsatzraten wurden mit der 15N-Verdünnungsmethode (15N pool dilution technique) bestimmt. Gasflüsse wurden sowohl unter Verwendung statischer Kammern gemessen, deren Sockel permanent im Boden angebracht waren, als auch unter Verwendung regelmäßig entfernter intakter Bodenproben, die zur Gasmessung in luftdichten Einweckgläsern inkubiert wurden. Messungen der N2-Fixierung und des N Kreislaufes erfolgten während der Regen- und Trockenzeit im Feld unter Verwendung intakter Bodenproben. THG Messungen wurden fünf Mal während des Zeitraumes von einem Jahr durchgeführt. Der Waldboden unserer Standorte war 4 Jahre lang zweimal im Jahr mit moderaten Mengen an N ( 50 kg N ha-1 Jahr-1) und P (10 kg P ha-1 Jahr-1) gedüngt worden und umfasste folgende Behandlungen: Kontrolle, N-, P- und N+P-Zugaben.
Das Kronendach trug 7-13 % zur gesamten Boden N2-Fixierung (Kronendach + Waldboden) bei, welche zwischen 0,8 und 1,5 kg N ha-1 Jahr-1 lag. N2-Fixierungsraten veränderten sich nur geringfüging mit der Höhenstufe, waren aber in der Trockenzeit deutlich höher als in der Regenzeit. N2-Fixierung im Waldboden wurde in N-Parzellen im Vergleich zu Kontroll- und P-Parzellen gehemmt, währen sie in Böden des Kronendachs in P-Parzellen im Vergleich zu Kontrollparzellen stimuliert wurde. Böden des Kronendachs trugen bis zu 23% zur gesamten mineralischen N-Produktion (Kronendach + Waldboden) bei; Brutto-N-Mineralisierung in Böden des Kronendachs lag zwischen 1,2 und 2,0 mg N kg-1 d-1. In Kontrollparzellen nahmen Brutto-Umsatzraten von Ammonium (NH4+) mit zunehmender Höhe ab, wohingegen Brutto-Umsatzraten von Nitrat (NO3-) keinen klaren Trend mit der Höhenstufe aufwiesen, aber signifikant durch die Saison beeinflusst wurden. Effekte durch Nährstoff-Zugabe unterschieden sich je nach Höhenstufe, aber kombinierte N+P-Zugabe erhöhte in der Regel auf allen Höhenstufen die N-Umsatzraten. CO2 Emissionsraten von Böden des Kronendachs berechnet auf der Basis der Fläche von Gaskammern (10,5 bis 109,5 mg CO2-C m-2 h-1) waren ähnlich denen vom Waldboden ähnlich und nahmen mit zunehmender Höhenstufe ab. Emissionen vom Kronendach, berechnet auf der Basis der Waldfläche (0,15 bis 0,51 Mg CO2-C m-2 h-1), machten jedoch nur 5-11% der gesamten Boden-CO2 Emissionen (Kronendach + Waldboden) aus. CH4 Flüsse (-0,07 bis 0,02 kg CH4-C ha-1 Jahr-1) und N2O Flüsse (0,00 bis 0,01 kg N2O-N ha-1 Jahr-1) von Böden des Kronendachs machten weniger als 5% der Gesamtflüsse von Böden aus. P-Zugabe reduzierte CH4 Emissionen in allen Höhenstufen, so dass Böden des Kronendachs als leichte CH4 Senken agierten (-10,8 bis -2,94 μg CH4-C m-2 h-1). Nur in 2000 m wurden Böden des Kronendachs unter N Zugabe zu leichten N2O Quellen (2,43 ± 3,72 μg N2O-N m-2 h-1), wohingegen P Zugabe die CO2 emissionen um ungefähr 50% reduzierte.
Die Ergebnisse zeigen, dass Böden des Kronendachs eine aktive Mikrobengemeinschaft besitzen, welche wertvolle Dienstleistungen hinsichtlich von Nährstoffkreisläufen für das Ökosystem des Kronendachs erbringt. Zusätzlich, war der Nährstoffkreislauf der Böden des Kronendachs in unseren Wäldern eindeutig an die Nährstoffverfügbarkeit des Waldbodens gekoppelt, was im Gegensatz zu Theorien steht, die besagen dass Böden des Kronendachs vom Nährstoffkreislauf der Waldböden entkoppelt seien. Wir haben festgestellt, dass Böden des Kronendachs in höheren Lagen eher einen wesentlichen Anteil des gesamten Wald-Nährstoffkreislaufes ausmachen; dies sollte in Studien berücksichtigt werden, die sich mit Nährstoffkreisläufen solcher Gegenden beschäftigen. Langfristige atmosphärische N- und P-Deposition verfügt über das Potenzial, die Dynamik von Nährstoffflüssen im Kronendach erheblich zu verändern. N-Deposition könnte die N2-Fixierung hemmen, wobei “hotspots“ weiterhin in Bereichen mit großen Mengen an P vorkommen. Interne N-Kreisläufe in Böden des Kronendachs werden wahrscheinlich durch N -und P-Deposition stimuliert werden, aber chronischen Nährstoffzugabe könnte auch zu erhöhten mineralischen N-Verlusten aus dem Bodensystem des Kronendachs führen. THG-relevante Prozesse in Böden des Kronendachs werden wahrscheinlich auch auf N- und P-Deposition reagieren, aber mit Ausnahme von CO2-Emissionen ist es unwahrscheinlich, dass Gasflüsse von Böden des Kronendachs wesentlich zum gesamten THG-Budget des Waldes beitragen.
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Green, Eleanor Virginia. "Nutrient addition and crop yield of an alley cropping system in the piedmont of Georgia." 2002. http://purl.galileo.usg.edu/uga%5Fetd/green%5Feleanor%5Fv%5F200205%5Fms.
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Tahir, Shermeen. "Clay amended sandy soil – influence of clay concentration and particle size on nutrient availability and organic carbon content after plant residue addition." Thesis, 2017. http://hdl.handle.net/2440/119196.
Full textAbstract:
Sandy soils have low water and nutrient holding capacity which limit crop growth. In the short-term, these constraints can be overcome by increased fertiliser application or irrigation. However, long-term solutions are needed to improve farm productivity and sustainability. Clay added to sandy soils may be such a solution. Compared to sandy soils, clay soils have smaller pores and higher cation exchange capacity and therefore greater water and nutrient holding capacity. Clay can also bind organic matter via cation bridges and thereby reduce its accessibility to decomposing microbes. In sandy soils with clay subsoil, the clay can be mixed into the sandy top soil by delving or spading. However, the clay subsoil is not uniformly distributed in the sandy top soil. It forms clay peds of varying size which creates a highly non-uniform soil environment with patches of sandy soil with clay peds next to sandy soil with little or no clay. The clay-rich patches can hold more water and nutrients compared to the surrounding sandy soil that could influence nutrient availability and organic C binding. Little is known about the influence of ped size and rate of clay added to sandy soil on nutrient availability and organic C binding after residue addition. The aims of the study were i) to determine the effect of clay addition rate and ped size in residue amended sandy soil on soil respiration, nutrient availability and organic C retention ii) to assess the effect of clay soil particle size and clay soil properties on nutrient availability and organic C binding after addition of residues with low or high C/N ratio iii) to determine the effect of clay addition rate and ped size on nutrient leaching after mineral fertilizer addition. A series of incubation experiments were carried out to assess the effect of clay addition rate and ped size on nutrient availability and organic C retention on < 53 μm fraction after mixing with low and high C/N ratio residue. In the first study, clay peds of 1, 2 or 3 mm size derived from a clay-rich Vertosol (73% clay) were added to a sandy soil (3% clay) at clay addition rates of 10% and 20% w/w. After addition of ground mature faba bean residue (C/N 37) at 10 g kg-1, the soils were incubated for 45 days at 80% of water holding capacity. Clay addition to sandy soil influenced nutrient availability after plant residue addition, particularly when small peds are added at higher rates. Sandy soil with clay peds had a greater maximum NH4 and P sorption capacity than sandy soil alone, sorption capacity was higher at 20% compared to 10% clay addition and greater with 1 mm than 3 mm peds. Retrieval of clay peds at the end of the experiment showed ped breakdown during the experiment but also formation of larger peds. Compared to the < 53 μm fraction added at the start of the experiment, total organic carbon (TOC) content of the < 53 μm fraction was up to two-fold higher, particularly in the smaller peds (1 and 2 mm). The study confirmed that claying can increase organic C sequestration, but also showed that organic C sequestration is likely to be greatest when the added clay peds are small. The capacity to bind organic C and nutrients may depend on clay soil properties such as mineralogy, clay concentration and exchangeable Fe and Al. A 45-day experiment was carried out to investigate the effect of clay type on nutrient availability and organic carbon retention with residues differing in C/N ratio (20 or 47). Two clay soils with smectite as a dominant mineral were used. They differed in smectite percentage [high (40%) or low (5-10%)], clay content (73 or 42%) and exchangeable Fe and Al concentration (low or high). The clay soils were added to sandy soil at rate of 20% w/w either finely ground or as 2 mm peds. Over 45 days, available N and P, microbial biomass N and P concentrations and cumulative respiration were greater with low C/N than high C/N residue. With low C/N residue, compared to sandy soil alone clay addition increased available N concentration and initial microbial biomass C and N, but decreased cumulative respiration and P availability. This study showed that addition of clay soil to sandy soil influences nutrient availability, but there were no clear differences between clay soils or sizes. The lack of differences between high and low smectite clay soil suggests that a high concentration of Fe and Al oxides can compensate for a lower clay concentration and proportion of smectite with respect to binding of organic matter and nutrients. In the previous studies, we found that clay addition had no consistent effect on cumulative respiration and ped size effect was variable. Secondly, low C/N ratio residue had stronger effect on nutrient availability due to its high decomposition rate and nutrient release compared to high C/N ratio residue. The third experiment was conducted to investigate that if clay addition has a different effect on respiration and nutrient availability when added as peds with a greater range of sizes (1, 3 and 5 mm) in presence of plant residue with lower C/N ratio. The aims of this experiment were to (i) determine the effect of clay addition rate and ped size in residue amended sandy soil on nutrient availability, and (ii) assess breakdown of peds during the experiment and organic C retention by the < 53 μm fraction of the peds. Clay soil addition to sandy soil amended with plant residue reduced respiration rate and available P concentration. Ped size had little effect on respiration and nutrient availability. Clay soil addition increased soil organic carbon retention compared to sandy soil alone. With respect to ped size, the experiment showed substantial ped breakdown and but also formation of larger peds over 45 days. The first three experiments were conducted over 45 days. But longer term studies are needed to better evaluate the effect of claying in the field. To investigate the effect of repeated addition of residue (finely ground wheat mature shoots added every 2 months) in clay amended sandy soil, a longer term (8 months) study was conducted with clay soil added as finely ground soil, 1 and 3 mm peds. The organic C content of the whole soil increased during the experiment with a greater increase in clay amended soils. The organic C content of the > 53 μm fraction was very low and changed little over time. With finely ground clay soil and 1 mm peds, the organic C content of the < 53 μm fraction increased mainly in the first 2 months while in 3 mm peds it increased over 6 months to reach similar concentrations as with finely ground clay soil and 1 mm peds. Excessive use of fertilizer in sandy soils can cause leaching of nutrient elements N and P into water ways and cause eutrophication. In the fifth experiment, clay soil was added in sandy soil at 10% or 20% clay soil w/w finely ground or as 2 and 5 mm peds with and without N and P fertiliser (27 mg N kg-1 and 7 mg P kg-1). The clay sand mixture (30 g) was placed in cores with nylon mesh at the bottom. The soils were incubated at 80% water holding capacity and leachate was collected weekly for 50 days. Clay addition significantly reduced leaching of N and P as compared to sandy soil alone. In sandy soil alone, the highest N (68%) leaching occurred after the first week whereas the highest amount (41%) of P was leached after two weeks. It can be concluded that clay addition to sandy soil can reduce the risk of nutrient leaching and enhance carbon sequestration in sandy soils by decreasing C loss via respiration and leaching. This effect will be greatest with finely ground clay soil or small peds.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food & Wine, 2017
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Kung, Tsai-Wei, and 龔采薇. "Effect of Dietary Sangrovit (SGV) Addition on Nutrient Utilization in Early Lactation Primipara Dairy Does and Weaned Kids." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/24ayek.
Full textAbstract:
碩士國立宜蘭大學
生物技術與動物科學系動物科學碩士班
107
Sangrovit (SGV) is a phytobiotic feed additive extracted from Macleaya cordata. The active substances are alkaloids which can enhance appetite and reduce intestinal inflammation. Such actions may improve nutrient utilization by animals. Experiment 1 investigated the effects of SGV (0.04 g/kg BW/day) in diets on nutrient digestion, nitrogen balance, milk traits and plasma traits in early lactation of primiparous dairy does. Primiparous dairy does (n=6) in early lactation were allocated randomly, according to the initial weight, to the control and the SGV treatments. During the period, water and block salt were given ad libitum, but bermudagrass straw (1.7 % body weight) and concentrate (1.31 % body weight) was restricted giving. The results show that, adding SGV, the water intake were not significant different. Total tract nutrient digestibility of non-fiber carbohydrate was lower than the control (P<0.1), but total tract nutrient digestibilities corrected for body weight were of no significant differences. Urine volume changes was not different, but urinary nitrogen excretion were increased (P<0.10). Milk volume, body weight changes and plasma traits were not different. Experiment 2 investigated the effects of SGV (0.04 g/kg BW/day) in diets on nutrient digestion, nitrogen balance, milk traits and plasma traits of weaned kids. Weaned kids (n=5) were allocated by random, according to the initial weight, to the control and the SGV treatments. During the period, water and block salt were given ad libitum, but bermudagrass straw (0.36 % body weight) and concentrate (1.39 % body weight) was restricted giving. The results show that, adding SGV, the water intake were not significant different. Total tract nutrient digestibility of dry matter was significant higher than control (P<0.05), and total tract nutrient digestibility of organic matter was also higher (P<0.1), but total tract nutrient digestibilities corrected for body weight were of no differences. Urine volume corrected for body weight was lower than control (P<0.1), and urine volume corrected for metabolic body weight was significant lower than control (P<0.05), but urinary nitrogen excretion were not significant different. The concentration of plasma total protein was significant lower than control (P<0.05) before the meal, and the concentration of globulin was lower than control (P<0.10) before the meal. Body weight changes were not significant different. Based on the results from the two thesis experiments, it appears that SGV decreased total tract nutrient digestibility of non-fiber carbohydrate in early lactation of primiparous dairy does, and weaned kids that supplemented with SGV, promoted nutrient digestion and reduced globulin concentrations before the meal.
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Biggs, Patrick Edward. "The effect of various feed additives on growth performance, nutrient utilization, and cecal microbial populations in poultry /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3223543.
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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3514. Adviser: Carl M. Parsons. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.
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Cárate, Tandalla Dayssy Maritza. "Effects of moderate Nitrogen and Phosphorus addition on the species composition and dynamics of the three seedlings community in tropical montane forests in southern Ecuador." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-002B-7C52-9.
Full textAbstract:
Las actividades antropogénicas han producido cambios en los ecosistemas alrededor del mundo. En las regiones tropicales de suramérica, la industrialización de las ciudades y el desmonte de los bosques por medio de quemas son las principales actividades que producen y expulsan contaminantes a la atmósfera e inducen cambios en los patrones de deposición de nutrientes y en el clima de los bosques primarios.
El nitrógeno (N) y el fósforo (P) son considerados los principales nutrientes que limitan crecimiento en las plantas ya que su disponibilidad es vital para la cadena de producción primaria de los bosques. Por esta razón, cualquier cambio en la disponibilidad de N o P en los suelos probablemente alteraría importantes mecanismos de la dinámica de los bosques tales como el crecimiento y la sobrevivencia. Cambios en el pH de los suelos (acidez), en los ciclos de nutrientes y en la cantidad de nutrientes afectan la disponibilidad de N y P y producen cambios en varios procesos fisiológicos de los árboles. Si bien bajas proporciones de nutrientes depositados han sido descritas para los bosque montanos del sur del Ecuador (ca. 5 kg ha–1 for N, 0.49 kg ha–1 for P), incluso a estos niveles se espera cambios en la estructura y en la dinámica de los bosques a largo plazo.
El grado de reacción de los bosques a los cambios en la disponibilidad de recursos es diferente con cada edad, estatus de sucesión natural, tanto como la etapa de vida de las plantas. Las plántulas de árboles (plantas jóvenes) deberían ser más sensibles a responder a cambios en la disponibilidad de nutrientes que los árboles del bosque maduro. Además, cualquier respuesta en la demografía de las plantas es probablemente más visible en las plántulas antes que en el bosque maduro debido a que las plántulas tienen una dinámica más rápida. Por esta razón, yo estudié la dinámica de la regeneración del bosque montano para entender qué procesos relacionados con los nutrientes están involucrados en el crecimiento y el establecimiento de las plántulas en ambos niveles, individual y de la comunidad de especies.
El experimento ecuatoriano de manipulación de nutrientes (NUMEX) ha sido diseñado para estudiar los cambios en el bosque montano como respuesta a la moderada fertilización. El experimento ha sido instalado en un gradiente altitudinal en tres principales sitios de estudio (1000 m.s.n.m.: Bombuscaro, 2000 m.s.n.m.: San Francisco, 3000 m.s.n.m.: Cajanuma) dentro del Parque Nacional Podocarpus y de la Reserva San Francisco. El experimento factorial consiste en cuatro bloques que contienen las parcelas experimentales (N, P, N+P, control) en cada sitio de estudio (16 parcelas por elevación). La fertilización ha sido realizada desde el 2008 añadiendo moderada cantidad de fertilizantes (i.e., 50 kg ha–1 y–1 of N and/o 10 kg ha–1 y–1 of P).
Para el estudio de la regeneración de las plántulas de especies de árboles, se utilizaron tres diferentes metodologías para evaluar la comunidad de especies y las respuestas de las especies comunes a la fertilización.
La primera metodología consiste en el monitoreo de las comunidades de plántulas en el bosque a 2000 m en tres años consecutivos (2011 – 2013). En 192 sub-parcelas de monitoreo (1m2 cada uno) en San Francisco, todas las plántulas y retoños fueron mapeados y etiquetados. Se estimaron y midieron altura, diámetro, herbivoría y producción de hojas en todos los individuos y se contó en número de nuevos reclutados en cada censo.
La segunda metodología determinó patrones de alocación de biomasa y la estequiometría de las plántulas de las seis especies comunes a lo largo del gradiente altitudinal. Las siguientes especies naturalmente abundantes fueron cosechadas: Clarisia racemosa y Pouteria torta en Bombuscaro, Graffenrieda emarginata y Palicourea angustifolia en San Francisco and Grafferieda harlingii y Hedyosmum purpuracens en Cajanuma. Morfología (alocación de biomasa, herbivoría y áreas foliares como: SLA, LAR, LA) y estequiometría de las hojas (contenidos de nutrientes y radios de N:P) fueron medidos y analizados.
La tercera metodología consiste en un experimento recíproco de transplante de plántulas (STE) dentro de las parcelas experimentales de NUMEX usando como especie focal, Pouteria torta, para evaluar respuestas específicas en el desenvolvimiento de las plántulas después de un año del experimento.
Los tres niveles de análisis mostraron respuestas diferentes a la fertilización de la comunidad de especies de plántulas y de las especies comunes. Contrariamente a los bosques bajos, la comunidad de especies en el bosque montano mostró una moderada respuesta a la fertilización. La densidad de los individuos decreció como consecuencia de la adición de nutrientes y como resultado del bajo reclutamiento en las parcelas experimentales, pero la mortalidad de las plántulas no fue afectada. Consecuentemente los mecanismos dependientes de la densidad activados por la absorción de N no mostraron evidencia de ser el principal eje impulsor de cambios en la densidad de las especies.
La comunidad de plántulas no mostró crecimiento por la adición de nutrientes a pesar de que las plántulas en los parcelas de N en general fueron siempre más altas con relación a las plántulas de las parcelas control. Sin embargo, la adición de N incrementó la herbivoría en todas las plántulas lo cual podría enmascarar las reales respuestas de crecimiento.
Las especies comunes aparentemente están bien adaptadas a los suelos relativamente pobres debido a que las especies no fueron favorecidas por los cambios en los nutrientes del suelo, mostrando pocos o ningún cambio en crecimiento o en la morfología de las hojas. En un largo período de tiempo, las especies comunes perderían su dominancia por ser menos competitivas que las especies de crecimiento rápido. Sin embargo, se necesitaría un período de tiempo de monitoreo largo bajo continua fertilización para producir cambios visibles en la composición de las comunidad.
Las respuestas específicas son difíciles de determinar en comunidades ricas en especies. Por ello, se llevó a cabo el análisis de las seis especies más comunes en un estudio complementario al monitoreo de las comunidad de especies de plántulas. Se evaluó la morfología de las hojas y plántulas además de la estequiometría de las hojas en plántulas cosechas en las parcelas experimentales. Ambos nutrientes (N y P), provocaron efectos en los atributos estudiados sugiriendo una estrecha co-limitación de N y P en las especies de árboles en todos los niveles altitudinales. Sin embargo, los radios de N:P y la frecuente respuesta de las especies a la adición del P indicaron que este nutriente podría ser más limitante que el N a lo largo del gradiente.
El grado de reacción de las especies estudiadas varía entre las seis especies. Mayor concentración de P en las hojas en relación al N fue evidente en todas las especies menos en Pouteria torta sugiriendo un alto consumo de P en las especies del bosque montano, similar a las respuestas encontradas en otras especies de plantas tropicales después de fertilización con P. El incremento de la herbivoría fue evidente solamente en dos especies aunque las respuestas fueron opuestas en G. emarginata (N y N+P) y en P.angustifolia (P) a 2000 m mostrando que la selección de las plantas por herbivoría es impulsada por la calidad de los recursos. Muchas de las especies estudiadas mostraron alta maximización de la adquisición de recursos debajo del suelo por la acumulación de biomasa en las raíces, con excepción de G. harlingii a 3000 m., la única especies que mostró alocación significativa de biomasa sobre el suelo como respuesta de la adición de nutrientes.
Las plántulas de Pouteria torta mostraron un cambio no significativo en el desenvolvimiento de las especies después de un año de fertilización en STE. Pouteria torta está bien adaptada a los suelos pobres, ya que la adición de N y P no alteró las concentraciones foliares de nutrientes. Sin embargo, la adición de N y N+P significantemente incrementó la mortalidad y el crecimiento de diámetro. La adición de P resultó en un incremento de la perdida de área foliar por herbivoría y desplazó la alocación de carbono al crecimiento de las raíces. Estas respuestas indicaron consecuencias en la fuerza de competencia en el sotobosque y el éxito de reclutamiento de Pouteria. Sin embargo, debido a que las respuestas son ambigüas de algunos atributos (crecimiento y herbivoría) y no están relacionadas con mortalidad es difícil establecer predicciones acerca de la futura abundancia de esta especie a largo plazo.
En conclusión, estudios complementarios demostraron que la limitación de un único nutriente en las especies de los bosques montanos no ocurre en un ecosistema rico en especies, a pesar de que los nutrientes están fuertemente correlacionados en mecanismos para la supervivencia y crecimiento. Por consiguiente, la fertilización con nutrientes afectaría varios mecanismos y dinámicas en las comunidades de plantas, el resultado de los cuales se desarrollaría en una escala de largo tiempo.
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Chiou, Shih-Jen, and 邱世仁. "Investigation of nutrient contents of Aloe vera and effect of additives on nonenzymatic browning of blanched Aloe vera." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/76313615833536356952.
Full textAbstract:
碩士靜宜大學
食品營養研究所
92
Abstract The purpose of this study was to investigate the nutritive compositions of the aloe vera and the effects of pH and additives on nonenzymatic browning of blanched aloe vera during storage. In order to establish an optimal blanching processing of aloe vera, the activity changes of peroxidase (POD) and polyphenol oxidase (PPO) of aloe vera were also assayed with different heating treatment. The physicochemical properties of aloe vera studied including vitamins, viscosity, molecular weight distribution, and monosaccharide composition of aloe vera. The results showed that the POD and PPO of aloe vera were inactivated after heating at 100℃ for 4 min. The contents of vitamin C and B1 were significantly decreased after blanching treatment but those of niacin and vitamin B2 differed significantly. The average molecule weight of aloe vera was decreased by heating treatment, resulting in the decomposition of aloe vera polysaccharide. The viscosity of aloe vera also declined with the increase of heating time. The extent of nonenzymatic browning of aloe vera was decreased by reducing pH value during heating. Besides, the extent of nonenzymatic browning of aloe vera significantly decreased with the increased concentrations of thio-compounds added during blanching treatment. Decreasing pH value and increasing of thio-compounds concentration tended to delay the formation of hydroxymethylfurfural (HMF) during storage, where sodium bisulfate gave the most significant effects on inhibiting the formation of HMF, comparing with glutathione and cysteine. According, changing the pH value and adding thio-compounds could efficiently inhibit the degree of nonenzymatic browning of blanched aloe vera during storage.
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Onal, Umur. "Development of artificial diets for delivery of water-soluble nutrients to altricial fish larvae." Thesis, 2002. http://hdl.handle.net/1957/30807.
Full textAbstract:
In the present study, the potential of low-melting point lipids, namely methyl
palmitate (MP) and menhaden stearine (MS), were studied for delivery of water-soluble
materials to fish larvae.
Addition of the solid emulsifier, sorbitan monopalmitate (SMP) resulted in higher
RE compared to the liquid emulsifier sorbitan sesquioleate (SSO). Additions of SMP
were found to have a positive effect on the stability of lipid spray beads (LSB) at
concentrations >10% (w/w) of lipid. LSB were shown to retain riboflavin with the
highest RE when the lipid matrix was composed of a mixture of MP+10% SMP+1O%
ethyl cellulose (w/w). Use of MP facilitated digestive breakdown of LSB by larvae of
zebrafish, Brachydanio rerio, and glowlight tetra, Hemigrammus erythrozonus, as
indicated by release of riboflavin from ingested LSB.
LSB composed of MS performed better than LSB composed of MP when
particulate glycine was incorporated within LSB. Highest retention efficiencies (RE) and
delivery efficiencies (DE) were achieved by LSB composed of 100% MS. RE and DE of
LSB were further improved when glycine was encapsulated as aqueous droplets rather
than in a particulate form. The overall performance of LSB containing tyrosine showed
that nutrients with similar water-solubilities to tyrosine can be very effectively delivered
to early fish larvae. Visual observation indicated that LSB composed of 100% MS were
broken down by larvae of clownfish, Amphiprion percula.
Zein-bound particles (ZBP) were not efficient in delivering riboflavin to fish
larvae due to high leaching rates. In an attempt to improve ZBP, we developed complex
particles (CP) containing LSB incorporated in a dietary mixture bound by zein, to obtain
a single particle type. The potential of LSB for delivery of free amino acids (FAA) was
evaluated when LSB were incorporated within CP. RE and DE for tyrosine were
significantly greater than those for alanine, glycine and serine. There was a significant
inverse correlation between RE for FAA and their solubilities where FAA with low
solubilites resulted in higher RE. Development of CP with high RE and DE for amino
acids is an important step towards formulating a diet to allow early weaning of fish larvae
onto artificial diets.Graduation date: 2003
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LIN, ZHENG, and 林正. "Effects of addition different fiber components to rabbits'diet on growth performance, nutrient digestibilities, hindgut fermentation and intestine structure of domestic rabbits." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/51929991786943128073.
Full text
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Müller, Anke Katrin. "Soil greenhouse gas fluxes under elevated nutrient input along an elevation gradient of tropical montane forests in southern Ecuador." Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0023-9920-3.
Full textAbstract:
Los suelos de los bosques tropicales desempeñan un papel importante en el clima de la Tierra mediante el intercambio con la atmosfera de grandes cantidades de gases de efecto invernadero (GEI). Sin embargo, esta importante función podría ser alterada por las actividades humanas causando el aumento en la deposición de nutrientes en los ecosistemas terrestres, especialmente en las regiones tropicales. Las causas de cómo el incremento de las cantidades de nutrientes está afectando los flujos de suelo de los GEI de los bosques tropicales es relativamente poco conocida, por ello los monitoreos de nutrientes in situ de los bosques montanos tropicales (BHT) son aún menos comprendidos. Ya que los BHT representan alrededor del 11-21% de la superficie forestal tropical, es de vital importancia predecir y cuantificar los cambios en los flujos de GEI del suelo en respuesta a la adición de nutrientes ya que podrían favorecer la retroalimentación a otros cambios globales. Esta tesis tiene como objetivo cuantificar el impacto de adición moderada de nitrógeno (N) y/o fósforo (P) en los flujos de tres GEI en suelo: dióxido de carbono (CO2), óxido nitroso (N2O) y el metano (CH4), a lo largo de un gradiente altitudinal (1000 m, 2000 m, 3000 m) de los BHT primarios en el sur de Ecuador.
Desde hace más de cinco años, se ha medido los flujos de GEI del suelo en un experimento de manipulación de nutrientes (‘NUMEX’, por sus siglas en inglés), con replicas para control, y la adición de N (50 kg N ha-1 año-1), P (10 kg P ha-1 año-1) y N+P. Las mediciones in situ se realizaron mensualmente utilizando cámaras ventiladas estáticas, seguido por un análisis de cromatografía de gases para conseguir una perspectiva más profunda sobre los procesos implicados en el intercambio suelo-atmósfera de GEI. Se realizaron nuevas investigaciones incluyendo el monitoreo de factores básicos de control (i.e. temperatura del suelo, humedad y las concentraciones del N mineral), los diferentes componentes de los flujos de CO2 del suelo, tasas de reciclaje netos de N y fuentes de los flujos de N2O del suelo. Con este propósito, se utilizó la extracción de hojarasca y técnicas de excavación de zanjas (trenching technique), incubación de las muestras in situ (buried bag method) y el etiquetaje de 15N de corto plazo.
Los flujos de GEI del suelo en los bosques que estudiados se mostraron en el rango de aceptado de los flujos de gases de otras BHT en elevaciones comparables, excepto para el N2O. Los flujos de N2O, que se derivan principalmente de la des nitrificación, fueron bajos para un TMF lo que se puede atribuir a los ciclos conservativos de N del suelo en nuestros sitios de estudios. Los suelos fueron fuentes de CO2 y N2O (la intensidad del recurso disminuye al aumentar la altitud) y en todas las elevaciones el CH4 es bajo.
Encontramos efectos de los nutrientes en todos los flujos de GEI medidos en cada elevación. Las respuestas de los flujos de CO2 del suelo cambian con la duración y el tipo de nutrientes adicionado. En 1000 m, la adición del N no afecta los flujos de CO2 del suelo, mientras que las adiciones de P y N+P disminuyeron los flujos en el primer y cuarto a quinto año. En 2000 m., la adición de N y N+P incrementa los flujos de CO2 en el primer año; a partir de entonces, la adición del N disminuye los flujos mientras que la adición de N + P no mostro ningún efecto la adición de P carece de efectos. En 3000 m, la adición de N además incrementó los flujos de CO2 constantemente; la adición de P y N+P aumentaron los flujos sólo en el primer año a partir de entonces no existió ningún efecto. Los efectos diferenciales de los nutrientes estuvieron relacionados a un estatus del N y P y respuestas variadas de los componentes de la respiración del suelo.
Las respuestas de los flujos de N2O y CH4 a la adición de nutrientes mostraron gran variabilidad entre años. Los flujos de N2O no se vieron afectados por la adición de tres a cinco años de N a pesar de las diferencias significativas observadas durante los dos primeros años del mismo experimento. Atribuimos la ausencia de las respuestas en años mas tardíos debido a los contenidos bajos de humedad del suelo en nuestro periodo de monitoreo 2010-2012. En todo el gradiente altitudinal, la adición de P disminuyó los flujos de N2O y las concentraciones de N mineral, presumiblemente debido a que alivió de la limitación del P en la producción primaria neta, lo que aumentó la captación de N a través de las plantas. La adición de N+P además mostró tendencias similares las respuestas a la adición de N solamente, pero con efectos menos fuertes debido a los efectos contrapuestos de la adición de P.
Durante los dos primeros años de la adición de nutrientes, los flujos de CH4 no se vieron afectados en ninguna elevación, lo cual atribuimos a la combinación de cantidades moderadas de nutrientes añadidos, la fuerte inmovilización de nutrientes, y la separación de la más alta capacidad de absorción de CH4 en el subsuelo de la superficie del suelo donde se añaden fertilizantes. En el tercer a quinto año, la adición de nutrientes del suelo aumentaron la captación de CH4, aunque los efectos de N y P variaron a lo largo del gradiente altitudinal: en 1000 m, la adición de N y N+P aumentó la captación anual de CH4 a 20-60%; en 2000 m P y N+P incrementaron la captación a 21-50%; y en 3000 m la adición de P y N+P incrementó la captación de CH4 a 34-40%. Estos efectos diferenciales de la adición de nutrientes pueden estar relacionados con el estatus inicial de del suelo y respuesta diferenciales de otros componentes del ecosistema a la adición de nutrientes en cada elevación.
Demostramos que los flujos de GEI del suelo y consecuentemente la red potencial de calentamiento global del suelo pueden cambiar considerablemente a lo largo de un gradiente de elevación, siguiendo una tendencia general de disminución con el aumento de la elevación. Los resultados indican además que la elevada deposición de N y P puede afectar los flujos de GEI del suelo en los BHT Andinos, pero las respuestas a los flujos de GEI a la adición de nutrientes depende del estatus inicial de los nutrientes del suelo, la duración de la adición de nutrientes y la variabilidad inter-anual de las condiciones climáticas. Puesto que los efectos de la adición de nutrientes fueron no lineares con el tiempo de exposición y a la par existen complejas interacciones con otros componentes del ecosistema, aún quedan muchas incertidumbres en la predicción exacta de los efectos de la deposición de nutrientes en los flujos de GEI. Sin embargo, ofrecemos los primeros datos sobre los efectos de nutrientes a medio plazo de N, P y N+P en los flujos de los tres principales gases de efecto invernadero del suelo a lo largo de un gradiente altitudinal de los BHT Andina. Nuestros resultados sugieren que la red potencial de calentamiento global de los suelos en todo el gradiente altitudinal podría aumentar ligeramente con la entrada contribución de N, mientras que podría disminuir con el aumento de la contribución de P y N+P.
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Ngo, Thi Thanh Hue A. "Compost addition and pre-planning soil moisture conditions alter soil nutrients, plant growth and nutrition, and the formation of mycorrhizas." Thesis, 2016. http://hdl.handle.net/2440/114122.
Full textAbstract:
Front matter only available electronically. The complete thesis in print form is available from the University of Adelaide Library.Composts are important materials to improve soil fertility. The release of nutrients from composts is affected by soil moisture. Recent work has shown that soil moisture conditions prior to planting can have a profound impact on soil nutrients, plant growth and nutrition, which is defined as the carry-over effect of soil moisture. However, the carry-over effect of soil moisture, especially in compost-amended soils has not been fully investigated. The present research aimed to investigate how soil moisture conditions prior to planting can alter available nutrients in the soil with and without compost addition. Arbuscular mycorrhizal fungi (AMF), which are abundant in the rhizosphere of most terrestrial plants, play an important role in nutrient uptake of plants. Thus, this study also investigated whether the pre-planting moisture conditions and compost addition affect the formation of mycorrhizas. A pot experiment was set up in a glasshouse-controlled condition over 88 days of the experiment. Soil moisture conditions were manipulated as wet (75% of field capacity (FC)), dry (25% FC) and cycle (one wet-dry cycle between 75% and 25% FC) treatments during pre-planting period. Soil moisture then was maintained constantly at 75% FC for all pots during planting period. Tomato and wheat were used as model plants to test potential carry-over effects of compost addition and pre-planting moisture conditions on plants. Overall, the results indicate a clear effect of soil moisture conditions prior to planting on plant growth and nutrition and mycorrhizal colonisation. The N content of plants was clearly associated with N availability in the soil. However, the P content of plants was not correlated with plant-available P in the soil. Tomato and wheat expressed superior growth in the pre-planting dry conditions where mycorrhizal colonisation of roots was also greatest, despite low available N nutrient in the soil at the time of planting. The study suggests that there is a possible synergistic effect of compost and mycorrhizal application in plant growth that needs to be further investigated.
Thesis (M.Bio.(PB)) -- University of Adelaide, Masters of Biotechnology (Plant Biotechnology), School of Agriculture, Food and Wine, 2016.