Dissertations / Theses on the topic 'Mineralization rate'

Broiler litter (BL) is a high value manure available to Kentucky crop producers to utilize as a fertilizer. The rate of BL application, timing of application, and method of application are all important factors to take into account when utilizing BL. A laboratory incubation was conducted to observe nitrogen (N) mineralization rates of BL amended soils over time under different conditions. Different application methods, application rates, watering frequencies, and bedding materials were used to determine their influence on N mineralization. Broiler litter applied on the soil surface, at lower rates, at lower watering frequency resulted in lower mineralization rates than BL that was incorporated, at higher rates and higher watering frequency. The rice hull bedding BL treatments had a significantly higher initial amount of NH4+-N than the wood-based bedding materials. The increased NH4+-N content produced a lower pH due to higher rates of nitrification. The difference in NH4+-N resulted in the rice hull BL treatments containing more inorganic N throughout the incubation. The wood-based BL contained significantly more carbon (C), zinc (Zn), and potassium (K). The results collected will help improve current nutrient recommendations and provide information that will help utilize BL more efficiently and economically.

Microbial decomposition of organic matter in aquatic environments plays an important role in natural fluxes of methane and carbon dioxide because the gases are end-products in microbial energy metabolism of organic matter. Microbial metabolism depends on the use of electron donors and electron acceptors in redox reactions that generate energy for growth and maintenance. Energy yields can be used to envisage specific patterns of microbial redox reactions and these predictions depend on the hypothesis that, in a specified environment, the metabolic reaction that yields most energy will dominate over any competing reactions. The energy yield hypothesis indicates a sequential order in electron acceptor use by microbes and also make it tempting to conclude that degradation rate of organic matter is different depending on available electron acceptors. The main purpose of this thesis was to study how the presences of different electron acceptors in freshwater sediments influence organic matter decomposition. Mineralization rates of organic matter under six different conditions regarding the electron acceptor availability were investigated in a river sediment sample from Stångån, Sweden, by measuring carbon dioxide and methane production using gas chromatography. This was done during a fixed time period, in vials containing a mixture of water, sediment, buffer solution and a dominating electron acceptor. Six different metabolic processes; aerobic respiration, denitrification, manganese reduction, iron reduction, sulphate reduction and methanogenesis were included. The overall result indicates similar mineralization rates in both oxic and anoxic treatments. The result also indicates that methane formation was present in the iron reduction and methanogenesis treatments and not evident in the oxic treatments. Sulphate reduction, denitrification and manganese reduction seems to inhibit methanogenesis, but the result also indicates that no significant total mineralization was apparent when NO3- and Mn(IV) were the dominating electron acceptors. The similarities between oxic and anoxic mineralization rates indicates that organic matter degradation rates are not dependent on available electron acceptors and that degradation rates of organic matter are independent of the thermodynamically based energy yield.

Doctor of Philosophy
Department of Horticulture, Forestry, and Recreation Resources
Rhonda R. Janke
The goal of this study is to clarify the influence of organic fertilizer sources on vegetable crop yield under different production systems. This research hypothesized that organic soil amendments will produce healthy and vigorous plants with similar or higher yields while improving soil organic matter levels compared to conventional amendments. Applying organic fertilizer sources can be cost-prohibitive; moreover, synchronizing timing of crop nitrogen demand with soil plant available nitrogen is essential to maximizing yield and reducing nitrogen pollution to the environment. The objectives of this study are to evaluate yield in relation to soil fertility status at different fertility rates for organic and conventional management in field and high tunnel production systems, to measure plant nutrient status in crop petioles and compare it to available mineral N levels in soil at different growing stages, and to determine the effect of nitrogen availability of organic compared to conventional fertilization on plant available nitrogen and crop yield under both systems. A latin square experimental design was conducted from 2008 to 2010 at Kansas State University Research Center in Olathe KS to evaluate an organically managed vegetable rotation of tomato (Solanum lycopersicum L. ‘Bush Celebrity’) and pac choi (Brassica rapa L. ‘Mei Qing’) under three fertility rates; control, low (composted poultry manure), and high (composted poultry manure and fish hydrolyzate) in contrast with conventionally managed soils under two production systems (field and high tunnel). The effect of these four contrasting systems was measured on plant and soil nutrient status. All plots had cover crops of rye during the winter and buckwheat in the summer between pac choi crops. Soil nitrate-N (NO₃-N) and ammonium-N (NH₄-N) were measured, as well as petiole sap nitrate (NO₃⁻). In tomato, additional soluble fertilizers had no direct effect on yield in both field and high tunnel. Compost application had a positive effect on organic matter. In pac choi, additional liquid fertilizer helped organic field plots obtain maximum yield. Soil mineral nitrogen were affected by production system and fertility source, but statistical significance varied by crop and stage. Petiole sap reflected treatment regimens but not necessarily soil N status at each plant stage. The study also addressed long term management practices on organic and conventional available nitrogen. An incubation study on the soil at the conclusion of the field experiment explored the relationship between N mineralization from potentially mineralizable nitrogen (PMN) compared to Illinois Soil Nitrogen Test (ISNT) in control and pre-plant application fertility treatment for both field and high tunnel systems. The results indicated that ISNT concentration values for all soils were below the proposed value for corn crop suggested by (Khan, 2001). ISNT correlated with PMN with the stronger correlation being in field plots. ISNT also correlated with OM in field. Fertility rate showed a significant effect on total carbon and total nitrogen in organic systems of both field and high tunnel plots. This study supports composted poultry manure to improve the fertility status of the soil and to obtain a yield equal to that of conventionally managed soil.

Continuous flow microcosms (50L volume, salinity 18-24 ppt) were used to examine the roles of heterotrophic protozoa and bacteria as phosphorus mineralizers. Nitrogen limitation was regulated by N:P supply ratios (5:1, 16:1) and growth rate was regulated by dilution rate (0.5, 0.25 volumes day&\sp{lcub}-1{rcub}&). Rates of carbon and phosphorus uptake from dissolved inorganic pools were determined using &\sp{14}&C and &\sp{lcub}32{rcub}&P tracer experiments and pre- and post-fractionation incubations. Based on uptake rates and on POP and POC values of the bacteria in the &<&1.0 &\mu&m fraction, mass balance estimates of bacterial mineralization were determined. An isotope dilution method was used to determine phosphorus mineralization in the unfractionated sample. Heterotrophic protozoan mineralization was calculated as the difference. Results showed that bacteria had a minor role as remineralizers of phosphorus, more often taking-up inorganic phosphorus than remineralizing it. Heterotrophic protozoa were the major remineralizers of phosphorus. Microcosm treatments with a greater supply of inorganic phosphorus over nitrogen had increased POP concentrations and increased phosphorus remineralization. The effect of dilution on phosphorus remineralization was temperature dependent. Greater remineralization occurred in the high dilution rate in the July through October experiments and less remineralization occurred in the high dilution rate treatments in the December and January experiments.

L'altération hydrothermale du manteau lithosphérique dans les dorsales médio-océaniques fournit un mécanisme de transfert de chaleur et de masse entre la terre profonde et l'océan recouvrant. Le manteau lithosphérique est constituée de roches ultramafiques, également appelées péridotites. Ils comprennent plus de 70% d'olivine, de pyroxènes associés et de phases minérales mineures. La percolation de l'eau de mer dans le socle ultramafique produit l'altération de l'olivine et des pyroxènes en serpentine par le processus de serpentinisation et il est associé à des réactions d'oxydation et de carbonatation (lorsque le CO2 est présent dans le fluide). Le processus de serpentinisation présente un intérêt particulier pour la production de H2, le stockage du CO2, le développement de la vie et la production de gisements de minerai économiquement intéressants concentrés dans les fumeroles hydrothermaux. La durabilité et l'efficacité des réactions nécessitent la pénétration et le renouvellement des fluides à l'interface fluide-minéral. Les failles et les fractures des détachements océaniques sont les zones hautement perméables qui permettent à l'eau de mer de pénétrer profondément dans le manteau lithosphérique. Cependant, le processus de serpentinisation conduit à la précipitation de minéraux de faible densité qui peuvent remplir le réseau poreux, colmatant les chemins d'écoulement qui peuvent modifier les propriétés hydrodynamiques et la réactivité des roches réagi.Ces travaux de thèse visent à améliorer la compréhension des effets en retour des réactions sur les propriétés hydrodynamique du milieu dans les zones hautement perméables au cours des premières étapes de l'altération du socle ultramafique. Il se concentre en particulier sur les changements de texture et les réactions chimiques des roches ultramafiques en évaluant les effets du (i) débit et (ii) des fluides salins riches en CO2. Deux séries d'expériences de percolation réactive ont été réalisées à T = 170-190°C et P = 25MPa. La première série d'expériences consistait à injecter de l'eau de mer dans des échantillonnes de poudre d'olivine compressé sur une large gamme de débits constants. La tomographie par rayons X de haute résolution a été acquise avant et après l'expérience avec des débits élevés; afin d'évaluer les changements dans la microstructure de la roche lors de la réaction de serpentinisation. La deuxième série d'expériences consistait à injecter des fluides salins riches en CO2 dans des échantillonnes de péridotite fracturés mécaniquement.Les résultats ont permis de différencier: (1) un contrôle du débit du flux à l'échelle du pore peut contrôler la composition du fluide local et le développement de différents chemins de réaction à l'échelle de l'échantillon. (2) Le développement de différentes chemins réactifs et les changements de texture dans la roche dépend de la concentration de CO2 dissous dans la solution. (3) La formation de minéraux carbonatés (MgCO3) peut stocker du CO2 sous forme stable de minéral à long terme. (4) Un contrôle de la concentration de CO2 dissous dans le fluide et du réseau de fractures peut améliorer / limiter l'efficacité du stockage de CO2 dans les réservoirs de péridotite fracturés.Ces nouvelles données suggèrent un contrôle complexe de la structure des roches ultramafiques dans le processus de serpentinisation et fournissent de nouvelles perspectives pour le stockage potentiel du CO2 dans les réservoirs fracturés à la péridotite
The hydrothermal alteration of the mantle lithosphere at mid-ocean ridges provides a mechanism for transferring heat and mass between the deep Earth and the overlaying ocean. The mantle lithosphere is constituted by ultramafic rocks, also called Peridotites. They comprise more than 70% of olivine, associated pyroxenes and minor mineral phases. The percolation of seawater into the ultramafic basement produces the alteration of olivine and pyroxenes to serpentine through the so-called serpentinization process and is associated to oxidation and carbonation reactions, the later when CO2 is present. The serpentinization process has special interest on H2 production, CO2 storage, development of life, and the production of economically valuable ore-deposits concentrated at hydrothermal vents. The sustainability and efficiency of the reactions requires penetration and renewal of fluids at the mineral-fluid interface. Oceanic detachment faults and fractures are the highly permeable zones allowing seawater derived fluids to penetrate deeply into the mantle lithosphere. However, the serpentinization process lead to the precipitation of low density minerals that can fill the porous network, clogging flow paths efficiently that may in turn modify the hydrodynamic properties and the reactivity of the reacted rocks.This PhD thesis aims at better understanding the feedback effects of chemical reactions on the hydrodynamic rock properties occurred on highly permeable zones during the earliest stages of alteration of the ultramafic basement. It focuses in particular on the changes in texture and chemical reaction paths of ultramafic rocks by assessing the effects of (i) flow rate and (ii) CO2-rich saline fluids. Two suite of reactive percolation experiments were performed at T=170-190°C and P=25MPa. The first suite of experiments consisted in injecting artificial seawater into porous compressed olivine powder cores over a wide range of constant flow rates. X-Ray µ-tomography of high resolution was acquired before and after the experiment run with high flow rates; in order to evaluate the micro-structural changes of the rock occurred during the serpentinization reaction. The second suite of experiments consisted in injecting CO2-rich saline fluids into peridotite cores mechanically fractured.The results allowed us to differentiate: (1) That, a control of flow infiltration rate at the pore-scale can control the local fluid compositions and the development of different reaction paths at the sample-scale. (2) The development of different reaction paths and textural changes in the rock depends on the concentration of CO2 dissolved in solution. (3) The formation of carbonate minerals (MgCO3) can store CO2 in a form of stable mineral at long-term. (4) A control of the concentration of dissolved CO2(g) and the fracture network can enhance/limit the efficiency of CO2-storage in peridotite fractured reservoirs.These new supporting data suggest a complex control of the structure of the ultramafic rocks in serpentinization process and provides new insights for the potential CO2-storage in peridotite fractured reservoirs

Environmental concerns about winter nitrogen (N) leaching loss limit the amount of biosolids applied to winter small grains in Virginia. Ten field studies were established 2012-2014 in Virginia to determine the agronomic and environmental feasibility of fall biosolids applications to soft red winter wheat (Triticum aestivum L.). Eight studies were located in the Coastal Plain physiographic province and two in the Ridge and Valley physiographic province. The effects of eight biosolids and urea N treatments on 1) biomass production at Zadoks growth stage (GS) 25-30, 2) soil inorganic N at GS 25-30, 3) soil mineralizable N at GS 25-30,4) N use efficiency (NUE) at GS 58, 5) grain yield, 6) end-of-season soil inorganic N, and 7) estimated N recovery were studied. Anaerobically digested (AD) and lime stabilized (LS) biosolids were fall applied at estimated plant available N (PAN) rates of 100 kg N ha-1 and 50 kg N ha-1. The 50 kg N ha-1 biosolids treatments were supplemented with 50 kg N ha-1 as urea in spring. Urea N was split applied at 0, 50, 100 and 150 kg N ha-1, with 1/3 applied in fall and 2/3 in spring. Biomass at GS 25-30 increased with urea N rate and biosolids always resulted in equal or greater biomass than urea. Soil mineralizable N at GS 25-30 rarely responded to fall urea or biosolids N rate, regardless of biosolids type. Biosolids and urea applied at the agronomic N rate resulted in equal grain yield and estimated N recovery in soils where N leaching loss risk was low, regardless of biosolids type or application strategy. Lime stabilized biosolids and biosolids/urea split N application increased grain yield and estimated N recovery in soils with high or moderate N leaching loss risk. Therefore, AD and LS biosolids can be fall-applied to winter wheat at the full agronomic N rate in soils with low N leaching loss risk, while LS biosolids could be applied to winter wheat at the full agronomic N rate in soils with moderate or high N leaching loss risk.
Master of Science

Lithium and tantalum mineralization in rare-element pegmatites has been studied in 4 field areas. Three field areas are within a pegmatite belt which stretches for 450 km from Steinkopf, Namaqualand in the west, to Kenhardt in the east along the Orange River in South Africa, incorporating Tantalite Valley, Namibia in the central area. This Belt is considered to be of 1200 my age. The 4th field area is in central Namibia in the Karibib-Usakos region of 500 my age. Lithium mineralization involves primary minerals, petalite and spodumene (crystallizing< 650° C) and amblygonite which crystallize from a magma +/- an aqueous fluid, and lithian mica which along with cleavelandite is one of the last mineral assemblages to form, probably these last two assemblages are replacement in origin. Petalite is dominant in the Karibib area and spodumene in Steinkopf, Namaqualand and Tantalite Valley. The Kenhardt area is poor in lithium in comparison with the western and central portions of the Pegmatite Belt. Amblygonite-montebrasite is present in Karibib and Tantalite Valley usually in association with cleavelandite and lithian mica. Hydrothermal low temperature replacements, < 400°C occur in spodumene in the Steinkopf and Tantalite Valley pegmatites, being pseudomorphed by albite and mica +/- sericite. Amblygonite-montebrasite in Karibib displays replacements of natromontebrasite (the first occurrence in Karibib, Namibia), crandallite, brazilianite and possibly cookeite. Apatite is always prominent at the contact. An unusual occurrence of Mn-tantalite lamellae, primarily parallel, lying in microlite, is intergrown with montebrasite at the Rubicon pegmatite, Karibib, suggesting simultaneous crystallization of these three minerals, i.e. Ta-dominated tantalite and microlite and LiAl(F/P04) involving late fluids rich in F, P and Ta. Mn-tantalite and Ta-rich microlite are the dominant Ta-minerals in the rare-element Li-rich pegmatites of Namaqualand, Tantalite Valley and Karibib. In contrast, columbite (Nb-rich) is prevalent in the Li-poor, less differentiated pegmatites in the eastern Pegmatite Belt near Kenhardt. Microlite replaces Mn-tantalite in Li-rich rare-element pegmatites in all three field areas. A uranmicrolite from Karibib, Namibia contains 14.35% UO2, 1.03% PbO, 56.12% Ta205, 13.18% Nb205, 0.58% Fe203, 6.87% CaO, 0.54% SrO, 0.59% MnO, 0.86% Na2O and 0.47% F. U-plumbomicrolite or Pb-uranmicrolite is intergrown with manganotantalite from the same pegmatite. Throughout one aggregate of microlite PbO varied from 21.98 to 1.57% and UO2 from 12.89 to 16.20%. Pb appears to be concentrated around the periphery of the crystal. Backscattered electron images reveal metamict textures in radioactive microlites and distinctive subspheroidal features. A uranoan microlite from Tantalite Valley, Namibia, revealed two essentially different compositions; a more hydrated rim area of 200 mum radius containing 7% higher Ta2O5, 10% lower CaO and 1.3% lower F than a main central area of slightly variable composition. Crystals of uranoan microlite from Steinkopf, Namaqualand contain remnants of a bismuth phase. Bismuth intergrowths with quartz reveal the presence of two rare-minerals, pyromorphite [Pb5(PO4) 3 C1] and m0ttramite[PbCu(VO4)OH], new data is given for these minerals. Ferro tantalite occurs at Rubicon mine. A schematic diagram is produced for the paragenetic sequence of mineral assemblage in each of the pegmatite areas in Karibib, Tantalite Valley, and Steinkopf, Namaqualand in relation to T and P of formation, and the magma and fluids effecting the crystallization sequence. Finally different fractionation trends of Ta-Nb, Mn-Fe, Rb-K and Cs-K in columbite-tantalites and lithian mica have highlighted variable paths of differentiation in contrasting rare-element pegmatites which may reflect different sources of original parental magma.

The potential for using RMP (refiner mechanical process) pulp mill fibre waste as a soil amendment was investigated by determining levels of net carbon mineralization. Under optimum conditions (laboratory incubation study), the pulp fibre waste, being a relatively homogeneous substrate, was found to mineralize at one rate of -0.0078 d⁻¹. In field applications the rate of net mineralization was slower, with rates of -0.0034 d⁻¹ and -0.0037 d⁻¹, as determined by soil respiration and litter bag trials, respectively. A loading effect was noted for this amendment, where increasing the levels of application was found to cause decreases in the mineralization rate. Using pulp fibre waste in forest landing rehabilitation appears to increase the levels of microbial activity in the surface horizon. The higher levels of productivity should lead to improvements in soil structure, and would be a better alternative to only tilling and fertilizing the soil.
Land and Food Systems, Faculty of
Graduate

The Bear Lodge alkaline complex in northeastern Wyoming (USA) is host to potentially economic rare-earth mineralization in carbonatite and carbonatite-related veins and dikes that intrude heterolithic diatreme breccias in the Bull Hill area of the Bear Lodge Mountains. The deposit is zoned and consists of pervasively oxidized material at and near the surface, which passes through a thin transitional zone at a depth of ~120-183m, and grades into unaltered carbonatites at depths greater than ~183-190m. Carbonatites in the unoxidized zone consist of coarse and fine-grained calcite that is Sr-, Mn- and inclusion-rich and are characterized by the presence of primary burbankite, early-stage parisite and synchysite with minor bastnäsite that have high (La/Nd)cn and (La/Ce)cn values. The early minerals are replaced with polycrystalline pseudomorphs consisting of secondary rare-earth fluorocarbonates and ancylite with minor monazite. Different secondary parageneses can be distinguished on the basis of the relative abundances and composition of individual minerals. Variations in key element ratios, such as (La/Nd)cn, and chondrite-normalized profiles of the rare-earth minerals and calcite record multiple stages of hydrothermal deposition involving fluids of different chemistry. A single sample of primary calcite shows mantle-like δ18O V-SMOW and δ13C V-PDB values, whereas most other samples are somewhat depleted in 13C (δ13C V-PDB ≈ –8 to –10‰) and show a small positive shift in δ18O V-SMOW due to degassing and wall-rock interaction. Isotopic re-equilibration is more pronounced in the transitional and oxidized zones; large shifts in δ18O V-SMOW (to ~ 18‰) reflect input of meteoric water during pervasive hydrothermal and supergene oxidation. The textural relations, mineral chemistry, and C and O stable-isotopic variations record a polygenetic sequence of rare-earth mineralization in the deposit. With the exception of one Pb-poor sample showing an appreciable positive shift in 208Pb/204Pb value (~39.2), the Bear Lodge carbonatites are remarkably uniform in their Nd, Sr and Pb isotopic composition: (143Nd/144Nd)i=0.512591-0.512608; εNd=0.2-0.6; (87Sr/86Sr)i=0.704555-0.704639; εSr=-1.5-2.7; (206Pb/204Pb)i=18.071-18.320; (207Pb/204Pb)i=15.543-15.593; (208Pb/204Pb)i=38.045-39.165. These isotopic characteristics indicate that the source of the carbonatitic magma was in the subcontinental lithospheric mantle, and modified by subduction-related metasomatism. Carbonatites are interpreted to be generated from small degrees of partial melt that may have been produced via interaction of upwelling asthenosphere giving a small depleted MORB component, with an EM1 component likely derived from subducted Farallon crust.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
The determination of the mineralization rate of organic compost is necessary for planning the most efficient way to use them. Thus, this study aimed to determine the carbon and nitrogen mineralization rate from organic compost produced from sheep and goat carcasses and its slaughtering spoils. Chromic Inceptisol (Luvisols) samples were incubated at an average temperature of 30.5 Â C with doses of 0; 3.75; 7.5; 15 and 30 Mg ha-1 of organic compost. To evaluate the carbon mineralization were used 100 g of soil incubated with these doses arranged in a completely randomized design (CRD) distributed in a split plot scheme. Samples were kept in glass containers tightly closed and the C-CO2 measurements were performed during periods of 0; 1; 2; 3; 4; 5; 6; 7; 9; 11; 14; 17; 20; 23; 26; 29; 33; 37; 41; 48; 55; 69; 83; 97; 112 and 126 days after the start of incubation. To determine the nitrogen mineralization rate (N), the doses of compost were incubated with 100 g of soil and distributed in a CRD with a 5 x 10 factorial arrangement. The assessment of inorganic N were performed at 7; 14; 28; 42; 56; 70; 84; 98; 112 and 126 days after the incubation beginning. Both models, the simple exponential and the double exponential, were not efficient to explain the dynamics of C mineralization for not consider the interactions that occurs when the compost is applied to the soil. A model that considers the soil C labile and recalcitrant compartments (ls and rs), protected and unprotected compartments of the applied organic matter (OM) (pc and dc) and a p factor that modifies the rate of mineralization of soil organic matter (SOM) when the compost is applied (C0 = Cls e-kltp + Crs.e-krstp + Cpc .e-kpst + Coc .e-kdct) was more efficient to explain the dynamics of C, considering the interactions with the SOM and the OM added. The suggested model has demonstrated that the rate of SOM decomposition is approximately 10% greater in the presence of the compost and the compost mineralization rate is 0.012 day-1, explaining the 97.95% of the variability in the data. The N mineralization was very fast since 40% of the standard dose of 7.5 Mg h-1 was found in the mineral form 14 days after the incubation. However, due to losses of inorganic nitrogen by NH3 volatilization, it was not possible to estimate the actual N mineralization rate.
A determinaÃÃo da taxa de mineralizaÃÃo de compostos orgÃnicos se faz necessÃria para o planejamento da forma mais eficiente de sua utilizaÃÃo. Deste modo, objetivou-se determinar a taxa de mineralizaÃÃo de carbono e nitrogÃnio de composto orgÃnico produzido a partir de carcaÃas e despojos de abate de ovinos e caprinos. Amostras de Luvissolo CrÃmico foram incubadas à temperatura mÃdia de 30,5 ÂC com doses equivalentes a 0; 3,75; 7,5; 15 e 30 Mg ha-1 de composto orgÃnico. Para avaliaÃÃo da mineralizaÃÃo do carbono foram utilizados 100 g de solo incubados com as referidas doses dispostas em um delineamento inteiramente casualisado (DIC) distribuÃdos em esquema de parcela subdividida. As amostras foram mantidas em recipientes de vidro hermeticamente fechados sendo as mensuraÃÃes de C-CO2 realizadas nos perÃodos de 0; 1; 2; 3; 4; 5; 6; 7; 9; 11; 14; 17; 20; 23; 26; 29; 33; 37; 41; 48; 55; 69; 83; 97; 112 e 126 dias apÃs o inÃcio da incubaÃÃo. Para a determinaÃÃo da taxa de mineralizaÃÃo do nitrogÃnio (N), as doses de composto foram incubadas com 100 g de solo e distribuÃdas em um DIC dispostas em um arranjo fatorial de 5 x 10. As avaliaÃÃes do N inorgÃnicoforam realizadas aos7; 14; 28; 42; 56; 70; 84; 98; 112 e 126 dias apÃs o inÃcio da incubaÃÃo. Tanto o modelo simples exponencial quanto o modelo duplo exponencial nÃo foram eficientes para explicar a dinÃmica de mineralizaÃÃo do C por nÃo considerarem as interaÃÃes que ocorrem quando o composto à aplicado ao solo. Um modelo que considera os compartimentos de C lÃbil e recalcitrante no solo (ls e rs), compartimentos protegido e desprotegidos da MO aplicada (pc e dc) e um fator p que modifica a taxa de mineralizaÃÃo da MO do solo quando o composto à aplicado (C0 = Cls e-kltp + Crs.e-krstp + Cpc .e-kpst + Cdc .e-kdct) se mostrou mais eficiente para explicar a dinÃmica do C, considerando as interaÃÃes da MO do solo com a MO adicionada. O modelo sugerido demonstrou que a taxa de decomposiÃÃo da MO do solo à aproximadamente 10% maior na presenÃa do composto e a taxa de mineralizaÃÃo do composto à de 0,012 dia-1, explicando 97,95% da variabilidade dos dados. A mineralizaÃÃo do N mostrou-se bastante rÃpida visto que 40% da dose padrÃo de 7,5 Mg ha-1 foi encontrado na forma mineral 14 dias apÃs a incubaÃÃo. No entanto, devido Ãs perdas de nitrogÃnio inorgÃnico por volatilizaÃÃo de NH3, nÃo foi possÃvel se estimar as reais taxas de mineralizaÃÃo do N.

Rare earth elements (REE) are an increasingly important group of metals due to their role in the development of modern technologies. Despite being abundant within the Earth’s crust recoverable ores are uncommon, and their mineralization isn’t as well understood as other abundant ore types. In this work, the mineralization of REE occurring in outcrop samples at Hicks Dome, a cryptoexplosive feature that resides in the Wauboukigou Alnöite Province in southeastern Illinois, was studied to determine the mode of mineralization and the origin of the REE. Xenotime-(Y) was identified with a scanning electron microscope in an intrusive breccia and emplaced during or shortly after the uplift which created the oval doming of the Paleozoic section. Whole rock REE concentrations from ultramafic dikes at Hicks Dome closely match global averages of lamprophyres and carbonatites, with a steep La to Lu slope, and enrichment of light rare earth elements. Hicks Dome has unique characteristics relative to the other intrusions in the Province, such as elevated REE, Th, and doming. These traits indicate that the dome was more closely related to an intrusive body at depth that sourced heat, volatile gases, and a suite of rare elements. Based on these data, the REE mineralization and thorium associated with the siliceous breccia is directly related to the alkaline ultramafic intrusion at Hicks Dome. The volatile rich, hot fluids emanating from the ultramafic magma supplied REE and thorium were mixed with the regional fluids responsible for the IKFD.

Hicks Dome is a mineralized intrusive center of alkaline ultramafic dikes, plugs and diatreme breccias that produced ~1200 m of structural doming of Paleozoic sedimentary rocks in southeastern Illinois. It is part of an igneous province referred to as the "Wauboukigou Alnöite Province" or "Middle Mississippi Alkaline Province". The 40Ar/39Ar dating of biotite and hornblende from igneous rocks throughout the region has consistently produced crystallization ages of 270 +/- 2 Ma (Early-Middle Permian). Hicks Dome lies near the intersection of two aulacogens, the Reelfoot Rift and the Rough Creek Graben. The igneous rocks in the Hicks Dome area range from dark-green, porphyritic dikes, through dikes with pelletal lapilli, to carbonate cemented breccias with country rock fragments and, locally, phenocrysts or xenocrysts and pelletal lapilli. Magmatic minerals include diopside, pargasite, phlogopite-biotite, titanomagnetite, ilmenite, and apatite, as well as carbonate (ferroan-dolomite - ankerite and calcite) of possible magmatic origin. This mineral assemblage only partly corresponds with other occurrences in the middle Mississippi Valley region igneous province as melilite, garnet, olivine, and perovskite were not identified in the Hicks Dome samples. The Hicks Dome igneous lithotype is defined here as a minette, a type of calc-alkaline lamprophyre. Evidence for this classification includes abundant Al-rich phlogopite-biotite, diopside, and pargasite, and the absence of melilite, garnet, and perovskite. Additionally, plotted Al2O3 vs. TiO2 compositions of biotite-phlogopite form a trend subparallel to that of minettes and alnöites, and Al vs. Ti values for most clinopyroxenes fall in the minette field. Some other igneous occurrences in the region are classified as types of ultramafic lamprophyres. For example, the North Hutson mine (Kentucky) and the Cottage Grove (Illinois) dikes are identified as alnöites and the Wildcat Hills dike (Illinois) is regarded as an aillikite. The Hicks Dome igneous suite contains 23 - 25 wt. % SiO2 and 13 - 21 wt. % CO2, whereas regional igneous rocks contain 33 - 36 wt. % SiO2 and 1 - 2 wt. % CO2. Such high CO2 values and inferred carbonate abundance is likely related to the elevated REE values at Hicks Dome. Finally, Hicks Dome samples show relative depletions in Ti, Nb, Ta, Zr, and Hf on a spider diagram compared to other regional igneous occurrences. These data indicate more variability among provincial igneous rocks than previously realized and perhaps two types of lamprophyres, one a calc-alkaline such as at Hicks Dome, and the other an alkaline ultramafic type. Rock samples from Hicks Dome and the surrounding region that were analyzed far exceed the silica cut-off to be considered a carbonatite (sensu stricto), yet a strong, consistent spatial association of abundant carbonate with igneous rocks throughout the region and similar patterns in LIL (large ion lithophyle), HFS (high field strength) and RE (rare earth) elements with carbonatites worldwide supports that magmatic carbon was part of the lamprophyre system at Hicks Dome. Carbon and oxygen isotope values for carbonate from Hicks Dome and other regional igneous samples do not plot within the field for primary carbonatite or the field for unaltered Mississippian limestone and instead form a broad linear trend between these two reference fields. The observed isotopic trend was possibly due to alteration of primary carbonatite by magmatic-hydrothermal and later low-temperature connate fluids. Parisite and/or synchysite, two REE fluorocarbonates of the bastnäsite group, and xenotime, a Y-(REE) phosphate, were identified in the Hicks Dome samples and occur as fibroradial aggregates in dissolution cavities in fluorite and carbonate and as anhedral crystals infilling microfractures and cleavage planes of phlogopite-biotite and paragasite. These textures clearly indicate the REE minerals are secondary phases most likely resulting from hydrothermal alteration-replacement by magmatic-hydrothermal fluids. A fertile (LREE enriched) lithospheric metasomatized mantle likely sourced the Hicks Dome carbonated alkaline silicate magma that, during emplacement, domed and brecciated the Paleozoic strata, expelled magmatic-hydrothermal fluids, and generated a F-REE mineralizing fluid with abundant carbonate. Igneous activity at Hicks Dome is genetically related to F-REE-base metal mineralization hosted by diatreme breccias, and likely contributed fluorine to the connate brines responsible for the F-base metal mineralization of the surrounding Illinois-Kentucky Fluorspar District (IKFD). Although resource estimates for the Hicks Dome area are beyond the scope of this work, an economic deposit of F, REEs, and/or base metals may be present at Hicks Dome and other igneous occurrences. The igneous lithotype, mineralogy, whole rock geochemistry, and regional geologic context support such a conclusion.

The Strange Lake rare-metal (Zr, REE, Nb, Be) deposit on the border of Québec and Labrador, Canada, contains a large resource of zirconium, rare earth elements and niobium. Much of the potentially economic mineralization was concentrated by magmatic processes, with additional remobilization of REE by hydrothermal fluids. The alkaline granite pluton (1240 ± 2 Ma; Miller et al., 1997) intruded along the contact between an Elsonian quartz monzonite massif in the southwest and paragneisses of Hudsonian age in the northeast.Much of the rare metal mineralization occurs in pegmatite lenses in the subsolvus granite, which are most abundant in the Main Zone in the middle of the pluton and the B-Zone at the northwest edge. Zirconium is hosted by a variety of silicates, mainly zircon, gittinsite and elpidite and Nb by pyrochlore. The LREE are present in pyrochlore, allanite-(Ce), monazite-(Ce), bastnäsite-(Ce) and parisite-(Ce), whereas the HREE are concentrated in zircon, gadolinite-group minerals, kainosite-(Y) and keiviite-(Y).A petrogenetic model is proposed for the B-Zone in which magmatic crystallization of HREE in zircon at the edges of pegmatite lenses was followed by leaching of the HREE by a high-temperature, Na-Cl-F magmatic fluid. The HREE were subsequently mobilized as Cl-complexes to the core of pegmatites where they reacted with a regional low-temperature, Ca-bearing brine, which caused the precipitation of fluorite and secondary HREE mineralization. Hydrothermal fluids altered the distribution of the REE, locally depleting them at the edges of the pegmatites and enriching them in the cores, which will be the main source of REE for potential future exploitation.
Le gisement de métaux rares (Zr, REE, Nb, Be) de Strange Lake, situé à la frontière du Québec et du Labrador au Canada, représente une grande ressource de zirconium, de REE et de niobium. Une grande partie de la minéralisation potentiellement économique a été concentrée par des processus magmatiques, avec remobilisation des REE par des fluides hydrothermaux. Géologiquement, ce pluton de granite alcalin, âgé de 1240 ± 2 Ma (Miller et al., 1997) se situe le long du contact entre un massif de monzonite quartzique d'âge Elsonien au sud-ouest et des paragneiss d'âge Hudsonien au nord-est.Une grande partie de la minéralisation en métaux rares se trouve dans les lentilles de pegmatite dans le granite subsolvus, les deux plus importantes étant la Main Zone dans le milieu du pluton et la B-Zone au nord-ouest, avec le Zr est associé à une variété de silicates, principalement le zircon, la gittinsite et l'elpidite et le Nb au pyrochlore. Les LREE sont associées au pyrochlore, l'allanite-(Ce), la monazite-(Ce), la bastnäsite-(Ce) et la parisite-(Ce), tandis que le HREE sont associées au zircon, la gadolinite, la kainosite-(Y) et la keiviite-(Y).Un modèle pétrogénétique est proposé pour la B-Zone dans lequel la cristallisation magmatique de HREE dans le zircon sur les bords de lentilles de pegmatite a été suivie par le lessivage des HREE par un fluide magmatique de haute température riche en Na-Cl-F. Les HREE ont ensuite été remobilisés sous forme de complexes de chlore au cœur des pegmatites où ils ont réagi avec une saumure régionale de basse température riche en calcium, qui a causé la précipitation de fluorite et de la minéralisation en HREE secondaire. Les fluides hydrothermaux ont affecté la répartition des REE, en appauvrissant localement les bords de pegmatites et en enrichissant les cœurs, qui feront l'objet d'une possible exploitation future.

Much of Haitian agriculture is characterized by subsistence farming systems on eroded and nutrient-poor soils. Implementation of Conservation Agriculture systems has proven effective at improving soil quality and crop yield in many areas of the world, including areas similar to those in Haiti. While most Haitian smallholder farmers are highly resource-limited and adoption of new technologies is limited, these farmers are known to adopt new crops and practices if benefits that outweigh risks are demonstrated. Cover crops that help provide soil cover and increase nutrient mineralization are one of the most potentially beneficial changes that could be made on most smallholder farms. However, before specific cover crop recommendations can be made, their potential benefits need to be quantified. One field experiment in the summer of 2013 assessed decomposition rates and nutrient mineralization from common cash crops and two potential cover crops either on the soil surface or buried at 15 cm. The relative difficulty and expense of conducting these types of field trials led to the development and assessment of a laboratory-based system that could be used to simulate plant residue decomposition and nutrient release under controlled conditions. Additional benefits of a laboratory-based study include the ability to test significantly more treatment combinations than would likely be possible under field conditions and to control nearly all other experimental variables, other than the desired treatment comparisons.
Master of Science

In Anbetracht des Kompromisses zwischen der Erzielung des höchsten Gewinns und der geringsten Umweltbelastung ist ein tiefes Verständnis der ökonomischen Folgen der Stickstoff (N) Düngung erforderlich. Die vorliegende Doktorarbeit liefert umfassende Einblicke in (i) die Auswirkungen des standortspezifischen N-Managements (SSNM) auf die Rentabilität und Risikominderung, (ii) die Auswirkungen von Unsicherheiten und Risikoeinflüssen auf optimale N-Düngergaben und (iii) das Potenzial und die Kosten der Vermeidung von Treibhausgas (THG) Emissionen durch N-Düngereduktion. Ein Modellierungsansatz wurde entwickelt, um die Wirkung von Ertrag und Proteingehalt, Wirtschafts- und Risikoauswirkungen sowie THG-Emissionen auf die N-Düngung zu simulieren. Die Ergebnisse der Arbeit zeigen, dass SSNM die Wirtschaftlichkeit verbessert, indem es eine höhere Weizenqualität und damit Preisprämien erzielt. SSNM reduziert das Risiko, die Backqualität nicht zu erreichen, und es gibt keine wesentlichen Nachteile beim Verlustrisikomanagement im Vergleich zum einheitlichen Management. Preisprämien für eine höhere Weizenqualität bieten Anreize für höhere N-Düngergaben. Prämien verflachen die Gewinnfunktion weiter, was unzureichende Argumente für eine Absenkung des N-Inputs aus der Wirtschaftlichkeitssicht liefert, selbst bei einer hohen Risikoaversion der Landwirte. Eine moderate Reduzierung der mineralischen N-Düngung kann die THG-Emissionen bei moderaten Opportunitätskosten mindern. Die THG-Vermeidung durch N-Düngereduktion in einer bestimmten Region kann unter Berücksichtigung kultur- und ertragszonenspezifischer Ertragswirkungen optimiert werden. Insgesamt liefert diese Arbeit wichtige Erkenntnisse über die Chancen und Nachteile der Anpassung der N-Düngergaben. Darüber hinaus leistet sie einen direkten Beitrag zur Identifizierung von kosten- und risikoeffizienten N-Managementoptionen und bildet die Grundlage für effektive politische Ansätze zur THG-Vermeidung durch selektive N-Düngereduktion.
Considering the tradeoff between achieving the highest profit and causing the lowest environmental impact, there is a need for a profound understanding of the economic consequences of nitrogen (N) fertilizer application. The present doctoral research provides comprehensive insights into (i) effects of site-specific N management (SSNM) on profitability and risk mitigation; (ii) impacts of uncertainties and risk implications on optimal N fertilizer rates; and (iii) potential and costs of mitigating greenhouse gas (GHG) emissions by N fertilizer reduction. A modelling approach was developed to simulate the response of yield, protein, economic and risk implications, and GHG emissions to N fertilizer application. Findings of the thesis show that SSNM improves profitability by achieving higher grain quality, thus, price premiums. SSNM reduces the risk of not reaching the baking grain quality and poses no considerable disadvantage on downside risk management compared to uniform management. Price premiums for higher wheat quality provide incentives for higher N input rates. Premiums further flatten the profit function, giving insufficient arguments for lowering N input from a farm profitability perspective, even in presence of high risk aversion of farmers. Moderate reduction of mineral N fertilizer can mitigate GHG emissions at moderate opportunity costs. GHG mitigation by N fertilizer reduction in a given region can be optimized considering crop and yield-zone-specific yield responses. Overall, this thesis provides important insights on chances and drawbacks of adjusting N fertilizer rates. Moreover, it makes a direct contribution in identifying cost- and risk-efficient N management options and provides a basis for effective policy approaches to reduce GHG emissions by selective N fertilizer reduction.

Le tungstène (W) fait partie des « ressources minérales critiques » définies par la Commission Européenne en terme d’approvisionnement pour de nombreuses applications technologiques. Le Massif Central Français (MCF), localisé dans la partie interne de la Chaîne Varisque Européenne, possède un potentiel économique significatif en W (>45 kt WO3) essentiellement sous forme de minéralisations disséminées dans des granites spécialisés ou associées à des systèmes filoniens hydrothermaux péri-granitiques à quartz-wolframite±cassiterite. Le but de cette thèse est (i) de caractériser les sources des fluides et des métaux impliquées dans la formation des minéralisations à W et (ii) de dater ces événements métallogéniques afin de les relier avec l’évolution orogénique de la Chaîne Varisque et notamment avec les événements métamorphiques et magmatiques fini-carbonifères. Ce travail est basé sur l’étude de plusieurs gisements hydrothermaux à W±Sn dans le MCF dans une approche multidisciplinaire combinant pétrographie et minéralogie détaillée, géochimie minérale et isotopique, géochimie en roche totale des granites et roches métamorphiques, géochronologie et étude des inclusions fluides. Les datations U-Pb des wolframites montrent que les minéralisations à W résultent d’événements hydrothermaux distincts sur une période d’au moins 40 Ma, correspondant à trois épisodes géodynamiques majeurs affectant la Chaine Varisque : (i) des minéralisations viséo-namuriennes (333-327 Ma) contemporaines de la compression syn-orogénique et de la mise en place des complexes leucogranitiques peralumineux à 335-325 Ma; (ii) des minéralisations namuro-westphaliennes (315-310 Ma) associées au jeu complexe de conditions compressives et extensives dans les zones internes de la Chaîne Varisque qui caractérise la fin du Carbonifère; (iii) des minéralisations stéphano-permiennes (298-274 Ma) mises en place en contexte post-collisionnel. L’analyse in situ des éléments mineurs et traces dans la wolframite a révélé l’existence de différents types de signatures géochimiques régionales, qui montrent de nombreuses similarités avec celles de granites évolués riches en métaux rares. L’étude détaillée du gisement de Puy-les-Vignes, exemple exceptionnel de minéralisation hydrothermale à W associée à un pipe bréchique, a permis de démontrer la superposition d’un stade à Nb-Ta sur la paragenèse primaire à W, interprété comme la contribution d’un fluide magmatique issu d’une coupole granitique à métaux rares. Ce résultat apparait similaire avec ceux déjà obtenus dans le cas du gisement de W d’Echassières, où le stockwerk à quartz-wolframite de La Bosse est recoupé par le granite à métaux rares de Beauvoir. De même, des aplites et pegmatites à métaux rares impactant les minéralisations à W±Sn ont été mises en évidence à Puy-les-Vignes et à St-Mélany. L’analyse par LA-ICPMS des inclusions fluides du granite de Beauvoir et du stockwerk de la Bosse a permis de caractériser la composition chimique des fluides primaires exsolvés lors de la transition magmatique-hydrothermale et de montrer leurs concentrations très élevées (102-103 ppm) en métaux rares (Sn, W, Nb) et la plus grande mobilité hydrothermale du Nb par rapport à celle du Ta. L’analyse minéralogique et géochimique de minéraux marqueurs des circulations fluides, tels que la tourmaline et les oxydes de titane, apporte de nouvelles évidences sur l’importance du rôle joué par les fluides métamorphiques régionaux précoces pour la mise en place des minéralisations à W-Sn. Enfin, cette thèse apporte des mises au point de développement méthodologique pour l’analyse multi-élémentaire des inclusions fluides et de la wolframite par LA-ICPMS
Tungsten (W) is part of the “critical mineral resources” as defined by the European Commission in terms of supply for several technological applications. The French Massif Central (FMC), located in the internal part of the European Variscan belt, is the host for a significant economic potential in W (>45 kt WO3), mainly as disseminated mineralization in specialized granites or associated with peri-granitic quartz-wolframite±cassiterite hydrothermal vein systems. The aim of this thesis is (i) to characterize the fluids and metals sources involved in the genesis of W mineralization and (ii) to date these metallogenic events in the framework of the orogenic evolution of the Variscan belt, especially in link with the late-Carboniferous metamorphic and magmatic events. This work is based on the study of several W±Sn hydrothermal deposits in the FMC using a multidisciplinary approach combining petrography and detailed mineralogy, mineral and isotope geochemistry, whole-rock geochemistry of granites and metamorphic rocks, geochronology and fluid inclusions study. U-Pb dating of wolframite show that the W mineralization formed during several distinct hydrothermal events in a period of at least 40 Ma, corresponding to three major geodynamic episodes affecting the Variscan belt: (i) Visean-Namurian (333-327 Ma) mineralization coeval with the syn-orogenic compression and the emplacement of peraluminous leucogranitic complexes at 335-325 Ma; (ii) Namurian-Westphalian (315-310 Ma) mineralization associated with a complicated setting characterized by coeval compressive and extensive conditions in the internal zones of the Variscan belt, typical of the late-Carboniferous; (iii) Stephanian-Permian (298-274 Ma) mineralization emplaced in post-collisional context. In situ analysis of minor and trace elements in wolframite showed the existence of different types of regional geochemical signatures, which share several similarities with those from rare-metal-rich evolved granites. The detailed study of the Puy-les-Vignes deposit, an exceptional case of hydrothermal W mineralization associated with a breccia pipe, allowed to demonstrate the superposition of a Nb-Ta stage on the primary W paragenesis, which is interpreted as the contribution of a magmatic fluid derived from a rare-metal granitic cupola. This result appears similar with those already obtained in the Echassières W deposit, where the La Bosse quartz-wolframite stockwork is cut by the Beauvoir rare-metal granite. Similarly, rare-metal aplites and pegmatites overprinting W±Sn mineralization have been shown in the Puy-les-Vignes and St-Mélany deposit. LA-ICPMS analysis of fluid inclusions from the Beauvoir granite and the La Bosse stockwork allowed to characterize the chemical composition of the primary fluids exsolved during the magmatic-hydrothermal transition and to show their very high concentrations (102-103 ppm) in rare-metals (Sn, W, Nb), and the higher hydrothermal mobility of Nb compared to Ta. Mineralogical and geochemical analyses of minerals markers of fluid circulations, such as tourmaline and titanium oxides, bring new evidences of the important role played by the early regional metamorphic fluids in the emplacement of W-Sn mineralization. Finally, this thesis gives new methodological developments for the multi-element analysis of fluid inclusions and wolframite by LA-ICPMS

Les granites à métaux rares sont issus de la cristallisation de magmas très évolués enrichis en volatiles et fondants (F, Li, P, B) et en métaux tels que Sn, Nb, Ta et W. Dans la chaîne Varisque d’Europe de l’Ouest, ils résultent d’un magmatisme tardi-orogénique spécifique. Depuis les années 60, de nombreuses études se sont intéressées à la signature géochimique de ces granites et différents modèles de genèse ont pu être proposés. Malgré cela, plusieurs questions subsistent; le contexte et les mécanismes de mise en place de ces granites particuliers ne sont que rarement abordés. Afin d’avoir une vision complète des processus et mécanismes responsables de (i) la genèse des magmas à métaux rares, (ii) la géométrie et la mise en place de ces granites, (iii) leur signature géochimique et leur enrichissement en métaux, une étude multi-approches et multi-échelles a été menée sur l’exemple du granite à métaux rares d’Argemela (Zone Centro-Ibérique, Portugal). Elle a été complétée par une étude expérimentale portant sur la genèse des magmas. Les résultats de l’étude structurale montrent que l’intrusion d’Argemela se met en place dans un contexte particulier. Plusieurs critères suggèrent une remontée verticale rapide et chenalisée du magma jusqu’à un niveau très superficiel, subvolcanique. L’étude pétrologique et géochimique du granite et des minéralisations associées a permis de mettre en évidence les évènements clés et les processus mis en jeu durant la transition magmatique-hydrothermale. Ceci a également permis d’appréhender les processus de concentration/transport des métaux et les mécanismes de dépôt des minéralisations. L’étude expérimentale indique qu’un seul stade de fusion partielle à faible taux ne permet pas de générer des magmas suffisamment enrichis en métaux. Cependant, un mécanisme de refusion de restites enrichies, qui reste encore à tester, pourrait produire les concentrations en métaux requises. Enfin, cette étude démontre la nécessité de combiner les approches car l’ensemble des processus sont interdépendants dans ce type de systèmes minéralisés
Rare metal granites result from the crystallization of highly evolved magmas enriched in volatiles and fluxing elements (F, Li, P, B) and in metals such as Sn, Nb, Ta and W. In the Western Europe Variscan belt, these granites are attributed to a late orogenic episode of rare metal magmatism. Since the 60’s, numerous studies have focused on the specific geochemical signature of rare metal granites and several models have been proposed for their genesis. However, several questions remain and, in particular, the context and mechanisms of magma emplacement have been only rarely addressed. In order to build a comprehensive understanding of magmatic, hydrothermal and tectonic processes and mechanisms responsible for (i) rare metal magma generation, (ii) magma emplacement and geometry, (iii) specific geochemical signature and metal enrichment, a multi-approach and multi-scale study has been performed on the example of the rare metal granite of Argemela (Central Iberian Zone, Portugal). It has been complemented by an experimental study on the genesis of rare metal magmas. Results of the structural analysis highlighted the special structural context of emplacement of the Argemela intrusion. Several criteria suggest a fast vertical and channelled magma ascent up to shallow subvolcanic levels. The petrological and geochemical study of the granite and related mineralization allow the identification of key events and processes involved during the magmatic-hydrothermal transition. Mechanisms of concentration/transportation and deposition of metals have been also specified. The experimental study indicates that a single step low degree partial melting is not efficient enough to produce rare metal magmas, since most are sequestered into the restite. However, remelting of enriched restitic assemblages, a mechanism which remains to be tested, could well produce the required rare metal concentrations. Finally, this study demonstrates the necessity to combine several approaches, since processes and mechanisms are interrelated in these mineralized systems

Les terres rares (TR) sont un groupe de métaux utilisés dans de nombreuses nouvelles technologies. Leur production est limitée, il est donc important de trouver de nouvelles sources d'approvisionnement. Les TR sont divisées en TR légères et lourdes, ces-dernières étant plus rares et ayant plus d'applications. Les granites et pegmatites alcalins sont des roches riches en TR lourdes. Une partie de cet enrichissement est d'origine magmatique, mais le rôle des fluides hydrothermaux (i.e. eau, CO2, méthane surtout) pose question. Ce manuscrit se concentre sur l'étude de minéraux communs (amphiboles, pyroxène, zircon) et des inclusions fluides de six zones du monde pour comprendre l'impact des fluides hydrothermaux par rapport à celui des processus magmatiques dans les granites et pegmatites alcalins. Les résultats montrent que la concentration et le fractionnement des TR sont liés à la circulation de fluides hydrothermaux riches en Na et K ou Ca et Na à des températures inférieures à 400 °C
The rare earth elements (REE) are a group of metallic elements used in many modern technologies. Their worldwide production is limited, hence it is necessary to find more sources. The REE are divided in light REE and heavy REE, the latter being rarer and with more industrial uses. Alkaline granites and associated pegmatites are rocks rich in heavy REE. Part of this enrichment is known to be magmatic, but the role of hydrothermal fluids (mostly water, CO2 and/or methane) in concentrating and fractionating these elements remains unclear. This work focuses on the study of minerals (amphiboles, pyroxene, zircon mostly) and fluid inclusions in six locations. The influence of hydrothermal fluids on REE relatively to magmatic processes is investigated in alkaline granites and associated pegmatites. The results show that REE concentration and fractionation is indeed linked to the circulation of hydrothermal fluids that are Na-K-rich or Ca-Na-rich and circulate at temperatures below 400 °C

A adição ao solo de resíduo vegetal de elevada relação C/N no sistema \"cana crua\", afeta o equilíbrio entre os processos de entrada e saída do N no sistema solo-planta-atmosfera. Assim, a presença da palhada modifica o agrossistema fazendo-se necessários ajustes no manejo da fertilização nitrogenada. Nesse sentido, quatro estudos foram desenvolvidos com os seguintes objetivos: (i) Avaliar as características produtivas e nutricionais da cultura da cana-de-açúcar de modo a identificar a fonte e a dose de N de maior eficiência agronômica; (ii) Quantificar a recuperação do N proveniente do fertilizante pela cana-de-açúcar; (iii) avaliar o potencial de inibição do íon cloreto na nitrificação no solo; (iv) avaliar as taxas de mineralização e imobilização do N-fertilizante e a sua interação com o Nnativo do solo. Em campo, foi conduzido um experimento em Latossolo Vermelho distróficocom cana-de-açúcar. O delineamento experimental foi o de blocos casualizados, com quatro repetições e nove tratamentos, com as fontes nitrogenadas: sulfato de amônio, YaraBela NitromagTM, nitrato de amônio e ureia na dose de 100kg ha-1 de N, cloreto de amônio, nas doses de N: 50, 100, 150 e 200 kg ha-1, e controle. Foram instaladas microparcelas com aplicação das fontes marcadas no isótopo 15N na dose de 100 kg ha-1 de N. Os fertilizantes nitrogenados foram aplicados manualmente, sobre a palhada. Posteriormente, amostras do solo coletadas previamente foram incubadas aerobiamente por um período de 21 dias. O delineamento experimental foi o inteiramente casualizado com quatro repetições e os tratamentos constaram da combinação de sulfato de amônio ou cloreto de amônio, na dose de 100 mg kg-1 de nitrogênio, com cloreto de potássio na dose de 100 ou 200 mg kg-1 de cloro. Avaliou-se, também, doses de cloreto de amônio (50, 100 e 200 mg kg-1 de N). As formas de N-mineral foram determinadas por meio de sistema de análise por injeção em fluxo. Amostras de solo foram, também, incubadas aerobiamente por um período de 20 semanas. O delineamento experimental foi o inteiramente casualizado com três repetições e seis tratamentos, constituindo-se um fatorial 3x2 (Namídico, N-amoniacal ou sem N versus com ou sem resíduo de cana). As fontes nitrogenadas (enriquecidas com 2% em átomos de 15N) foram aplicadas superficialmente no solo na dose de 100 mg kg-1 de N e o resíduo de cana-de-açúcar incorporado na dose de 5,2 g kg-1. O fornecimento de doses de N na forma de cloreto de amônio resultou em decréscimo de produtividade de colmos e açúcar. As fontes nítrico/amoniacais promoveram maior atividade da enzima redutase do nitrato nas folhas da cana-de-açúcar, porém, não apresentaram influência no acúmulo total de N. O aproveitamento do N-fertilizante pela cana-de-açúcar foi da ordem de 60% nos estádios iniciais, reduzindo-se para aproximadamente 20% próximo à fase de maturação. O íon cloreto reduziu a concentração de nitrato no solo devido a ação do ânion na reação de nitrificação. A incorporação de resíduo de cana-de-açúcar ao solo promoveu maiores taxas de imobilização do N e a aplicação de sulfato de amônio resultou em maior mineralização do N nativo do solo comparado a ureia.
The addition of plant residue with high C/N ratio to the soil in a \"green cane\" system affects the balance of input/output processes of N in a soil-plant-atmosphere system. Thus, the presence of straw modifies the agroecosystem requiring adjustments in management of nitrogen fertilization. Accordingly, four studies were developed to: (i) evaluate the nutritional and productive characteristics of sugarcane crops to identify the source and N rates of greater agronomic efficiency; (ii) quantify the sugarcane N recovery from fertilizers; (iii) assess the potential inhibition of chloride ion in reaction to soil nitrification, (iv) evaluate mineralization and immobilization rates of fertilizer-N and their interaction with the native soil N. We conducted a field experiment on a Typic Hapludox with sugarcane, in the 2009/2010 harvest. The experimental design was a randomized block with four replications and nine treatments with nitrogen sources: ammonium sulfate, YaraBela NitromagTM, ammonium nitrate and urea at 100 kg N ha-1, ammonium chloride at N doses: 50, 100, 150 and 200 kg ha-1 and control. Microplots were installed with application of nitrogen sources labeled 15N at 100 kg N ha-1. Nitrogen fertilizers were applied manually over straw. Subsequently, previously collected soil samples were incubated aerobically for 21 days. The experimental design was completely randomized with four replications and the treatments consisted of ammonium sulfate or ammonium chloride at 100 mg N kg-1 with potassium chloride at a chlorine dose 100 or 200 mg kg-1. We also evaluated doses of ammonium chloride (50, 100, and 200 mg N kg-1). Forms of mineral-N were determined by Flow Injection Analysis (FIA) system. Soil samples were incubated aerobically for 20 weeks. The experimental design was completely randomized with three replications and six treatments, comprising a 3x2 factorial (amidic-N, ammonium- N or without N versus with or without cane residue). Nitrogen sources (enriched with 2 atom% 15N) were applied to the soil surface at a N dose of 100 mg kg-1 and residue sugarcane incorporated at 5.2 g kg-1. The N supply in ammonium chloride form resulted in decreased yield of sugar and stalks. Nitric-ammonium sources promoted higher activity of nitrate reductase in sugarcane leave; however, they did not affect total N accumulation. The sugarcane recovery of fertilizer-N was approximately 60% in early stages, dropping to about 20% near the maturity stage. The chloride ion reduced nitrate concentration in soil due to the anion action in the nitrification reaction. The sugarcane residue incorporation to the soil showed higher N immobilization rates and the use of ammonium sulfate resulted in higher N mineralization rates of native soil N compared to urea.

Tests were conducted for 71 pesticides in weekly bulk (wet + dry) deposition samples collected from May 25 to September 21 over two years at two sites in the City of Winnipeg, Canada. Twenty-one pesticides and their metabolites were detected in this study and 99% of samples collected contained mixtures of two or more pesticides. Malathion and glyphosate were the largest contributors to bulk deposition in 2010 and 2011, respectively. A second study examined the mineralization of 2,4-D and 17β-estradiol using a novel in-field soil microcosm study and a series of laboratory experiments under different temperature incubations. Results indicated that temperature fluctuations do not greatly affect the amount or rate of mineralization relative to the traditionally constant laboratory incubations of 20°C; however long-term freezing of soil reduced potential mineralization over time. This research advances scientific knowledge of agri-chemical fate and provides data for strengthening current environmental policy analysis in Canada.

碩士
國立宜蘭大學
森林暨自然資源學系碩士班
100
Abstract The soil fertility in Taiwan agricultural soil is not well, coupled with the intensive farming practices, the soil fertility has severely depleted in Taiwan. In order to maintain crop production, the farmers in Taiwan must apply a lot of fertilizer, especially nitrogen fertilizer. Over a long time, not only spend costly in fertilizer, but the soil could be degraded. The aim of this study was to explore the impact of different biochar application rates on soil nitrogen mineralization. This study also supposes that if biochar application could significant promote soil nitrogen mineralization in Taiwan agricultural soil, the farmer could reduce the amount of fertilizer application and the possibility of soil degradation. Three soil series were selected in this study, including Pingchen, Erlin, and Annei soil series. The objective of this study was to investigate the effects of biochar application rates on soil nitrogen mineralization in the condition of applied swine manure compost. The results show that: in part of the pH of soil extracts, of any amount are the Pingchen soil series (Pc), the pH value significantly lower than the other two soil series; in Pingchen soil series and Erlin soil (Eh) series, adding biochar to improve the effect of soil pH is very rapid, relatively is relatively short, while Annei soil series (An) slower performance, but can last longer. In the same soil series with different amounts of comparison, the result is to add the amount of the sample, the pH value is relatively high, and with the addition of biochar to improve and increase the pH of soil extracts. Part of the soil out of the Electric Conductivity (EC), no matter what amount, are Eh EC values of soil series was significantly higher than the other two soil series. EC values of Pc soil series to add biochar samples significantly higher, while the EC value of Eh and An soil series is almost not added. Done extract pure water on the soil samples, to observe the release of soil Dissolved Organic Carbon (DOC), the results of the Pc> An> Eh. In which soil series, add the biochar does not significantly affect the DOC released during the experiment, biological carbon consumption by the microorganisms. The results of soil nitrogen, ammonium nitrogen (NH4+-N) and nitrate (NO3--N) content was significantly higher than the other two soil series of Pc soil series. Comparison of the amount, only the Pc soil series will add biochar to reduce NH4+-N release amount. Other soil series in the 2% biochar added, NO3--N emissions will lower emissions than other groups. Total inorganic nitrogen trends are similar to the result of NO3--N. Therefore, add the effect of biochar on soil nitrogen mineralization(Avoid losses for the save of inorganic nitrogen ) in addition to the Pc soil series is recommended to add the biochar does not exceed 0.5%, Eh and An soil series is recommended that the dosage does not exceed 1%. Beyond this range will significantly reduce nitrogen mineralization rate. However, the impact of biochar on soil and crops, there are many. To determine if the biochar as a whole, is a positive effect on soil and crops, also need to undertake a follow-up study to determine.

The Round Top laccolith is considered to be one of the youngest laccoliths in a series of five known as the Sierra Blanca peaks, located in Hudspeth county, Texas. The laccolith is anomalous within the region in that it is peraluminous and enriched in HREEs, F, and U, and is comprised of intermingled discrete packages of various rhyolite types. The laccolith rhyolite varies in color from gray, purple, red, and tan, which combine locally to form distinct geometric mottled textures. The general composition of the rhyolite is 48-52% potassium feldspar, 28-30% quartz, 8-14% plagioclase feldspar, 4-5% annite biotite, 2-3% magnetite-hematite, 1% zircon, and 1% trace phases. The morphology of the trace phases suggests quenching of a late-stage volatile-rich vapor phase at the time of the laccolith formation. The rhyolite displays a wide array of unique mineralogical characteristics indicative to rapid emplacement and metastable crystallization conditions, including three-part quartz phenocrysts, hourglass sector-zoned potassium feldspars, and late-stage anhedral zircons. Unique accessory and trace phases include cassiterite, cerianite-(Ce), changbaiite, columbite, cryolite, tantalite, thorite, yttrofluorite, yttrocerite, and two unidentified minerals named (W) and (X). Initial alteration of the laccolith by high temperature volatile-rich vapor during the late stages of crystallization caused the partial dissolution of the feldspars and quartz. Subsequent quenching of this high temperature vapor phase produced the abundant interstitial, and pore filling REE-fluorides common to the laccolith. The variation in rhyolite color and the presence of the mottled textures are a direct result of partial oxidation of the laccolith by secondary fluids. The oxidizing fluids migrated within the laccolith along an extensive fracture network, altering the adjacent wallrock by oxidizing magnetite phenocrysts to hematite. The gray, purple, and red rhyolite types reflect an increase in turbidity caused by hematitic inclusions primarily within the pore spaces of the potassium feldspar portions of the groundmass. The tan rhyolite is locally restricted to the base of the laccolith and has been subjected to an intense degree of alteration independent of the other rhyolite types, primarily indicated by the conversion of feldspars to clay. Petrographic, microbeam, and geochemical studies have determined little variation in REE concentration between the three rhyolites of similar alteration intensity, but have indicated a depletion in LREEs within the more altered tan rhyolite. The average REE+Y content for the rhyolites sampled (n=11) ranges between 249 ppm and 518 ppm. The REE+Y concentrations between rhyolite samples of the same type show some variation, possibly indicating a correlation between alteration and REE+Y abundance and/or innate heterogeneity in the vapor phase during the initial laccolith formation. The magma emplaced at Round Top underwent a prolonged evolutionary process of fractionation/differentiation as evident by the unusual mineral assemblage and geochemical enrichment associated with the laccolith (e.g. extremely negative europium anomaly, and the positive La/Yb correlation). Future exploration for Round Top style REE-deposits should center within long-lived, tectonically active and complex regions where laccoliths are likely to exist. Specifically, exploration should focus on identifying the youngest laccolith in a felsic series, as this is the most likely to contain the greatest abundance of incompatible elements within the laccolithic group. The early alteration of feldspars by the high temperature vapor phase was crucial in the development of the REE+Y enrichment at Round Top. The feldspar dissolution provided abundant open pore space that was subsequently filled by the REE-fluorides. Thus, exploration should additionally seek laccoliths that have undergone a similar early alteration process, and expand to potential laccolith groups not yet exposed by erosional processes.
text

Thesis (Ph. D.)--Florida State University, 2005.
Advisor: Dr. Joel Kostka, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (viewed June 22, 2005). Document formatted into pages; contains xi, 108 pages. Includes bibliographical references.

Reclamation success is highly dependent upon final soil quality of stockpiled soils, such as those found Cold Lake Oil Sands Region. Stockpiled soils, however, are generally poor in quality. Soils were amended with, biochar (BC), humalite (HU), a sub-bituminous coal; and peat (PT), as well as 50:50 blends of biochar:humalite (BCH) and biochar:peat (BCP). These amendments were applied at rates of 0, 6.55, 13.1 and 26.2 g C kg-1 each. Biochar, PT, and BCP applied at the rate of 26.2 g C kg-1 were found to reduce N2O emissions by 34, 54, and 70%, respectively, relative to the control. Within the bioassay, BC and PT amendment resulted in a 38 and 40% increase in dry matter yield (DMY) respectively. Finally, amendment typically resulted in significant net decreases in Olsen P values, while nitrate and ammonium concentrations were high in PT amended soils. In general, PT had the best overall performance.
October 2015

Phosphorus (P) is an essential plant nutrient that may limit plant growth and agricultural productivity if not available for crop plant uptake in sufficient quantities at the time required. Many Australian soils are deficient in available P, despite a long history of P fertilizer application, and this is due to fertilizer P rapidly becoming unavailable largely through biochemical fixation. The resulting low P fertilizer efficiency, coupled with rapidly rising cost of fertilizers, has increased interest in biological cycling of P from sources such as crop residues. However, to date, much of the Australian research has focussed on soils with relatively high organic matter content (> 2%) and relatively heavy texture i.e. medium to high clay content. Furthermore, although there is information on pasture residue decomposition and P release for sandy soils with low organic matter in Australia, a recent shift to continuous cropping systems means that information for a range of crop residues is required but is not currently available. Therefore the aims of the work described in this thesis were to (i) increase the efficiency of P use when crop residue P are applied to crops and (ii) determine the effect of crop residue biochemical quality on decomposition rates, soil P dynamics and plant P uptake in light textured sandy soils with low organic matter which are typical of a large proportion of the southern Australian wheat growing area. A further aim was to investigate the effects of combined additions of plant residue and P fertilizer on P cycling in these soils, a scenario highly relevant to farming systems. A series of soil incubation and plant growth experiments were undertaken to characterize P dynamics in soil following addition of a wide range of crop residues (total 15) collected from agricultural sites throughout South Australia. The residues, differing in age and biochemical quality, were young shoots of canola, lupin, pea, lucerne and lentil; mature shoot residues of canola, lupin, pea and wheat and mature root residues of wheat, canola and lupin. The concentration of total and water soluble P, C, and N in the residues was measured using standard wet chemical analyses and the carbon chemistry was determined by NMR spectroscopy. Decomposition of crop residues was continuously monitored over a period of up to 140 days by measuring soil respiration. Available P and microbial biomass P and C were also assessed at different times during the incubations. The total P in residues ranged from 0.16% to 0.32% and 0.05% to 0.08% in young and mature shoots, respectively. Water-soluble P was related to residue total P and ranged from 29% to 81% and 13% to 29% of total P in young and mature shoots, respectively. The C: P ratio ranged from 133: 1 to 253: 1 and 504: 1 to 858: 1 in young and mature shoots, respectively. Phosphorus availability and microbial P uptake differed between soils amended with crop residues and soluble P fertilizer as triple super phosphate (TSP). Soil respiration rates were significantly higher in soils amended with crop residues than in the soils amended with TSP or the unamended control in the first 58 days of incubation. In an experiment in which residues and TSP were added at a rate of 10 mg P kg⁻¹, available P was greater for TSP than residue-amended soil, whereas microbial P showed the opposite trend. Respiration rate and microbial P were positively correlated with C addition rate, which was highest in mature wheat residue because it had the lowest P concentration. In order to assess when P released from the residues is available for plants, wheat was grown over three consecutive crop periods with each period lasting for 4 weeks. Young residues with high content of water soluble P, C, N and amide and low lignin and phenolic content decomposed faster than mature residues. The C type and amount added with residues controlled the dynamics of P availability. Surprisingly, canola mature root increased available P and plant growth as much as young shoot residues while root residues of wheat and lupin resulted in P immobilization and low plant growth. Compared to canola young shoot, canola mature root has a higher total P concentration and a lower C: P ratio. Plant P uptake was positively correlated with residue total and water-soluble P content and negatively correlated with residue C: P and C: N ratio and amount of C added with the residues. In another experiment where residue was added at 2.5 g C kg⁻¹ soil and compared with TSP (4 and 10 mg P kg⁻¹ soil), available P and plant P uptake decreased in the following order: TSP-10P > canola root ≥ young shoot ≥ TSP-4P > control > mature shoot. Microbial P was greater with residue addition than with TSP and in the control. Residues with low total P and high C: P ratio resulted in P immobilisation in the microbial biomass. Therefore, residues with high total P and low C: P ratio can be an important source of P for plants. Net P immobilisation of mature wheat residues (0.07% P) was significantly reduced by combining wheat residue (C: P ratio 615: 1) with TSP leading to a C: P ratio of 155: 1 to 310: 1. Furthermore, the combination of wheat residue with TSP increased available P in residue and TSP-amended soils by 3.0 mg P kg⁻¹ soil, which was shown to be sufficient to support wheat growth in the early stages of development in the other experiments. Although water-soluble P fertilizers provide plants with immediately available P, a large proportion becomes unavailable over time. Addition of low C: P residues on the other hand, may not result in high amounts of immediately available P, but the P supply is more sustained due to P release from decomposing residues and turnover of microbial biomass P. Phosphorus immobilization after addition of residues which have high C: P ratio (615: 1) may be offset when residue is applied together with inorganic P fertilizer if the resulting C: P ratio is 300: 1 or less. Overall, this study has highlighted the potential role that crop residues, either alone or in combination with inorganic P, can play in increasing P availability in the light textured, low organic matter, P-limited soils typical of many southern Australian farming systems. The results provide important quantitative information on the potential of a wide range of crop residues to supply wheat with P, and how additions of inorganic P interact with residue decomposition and influence available P supply. This quantitative information will be valuable for the construction or validation of mechanistic models of residue decomposition relevant to low organc matter light textured soils in farming systems of southern Australia, and will ultimately assist in the development of economic management strategies for minimizing P fertilizer inputs and maximizing the benefits of biological cycling of P.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

Natural processes that cause differences in rates of decomposition and mineralisation of organic plants matter in soils of Sumava mountains' glacial lakes were studied using plant litter dominant in understorey of spruce forest in watershed of two lakes, Plesne and Certovo. The aim of this study is to determine the effect plant liter chemistry on decomposition and mineralisation rate. We hypothetize that chemistry of liter of understorey vegetation significantly affect N mineralisation / immobilisation in siols. During four month laboratory experiment were studied the effect of litter quality characteristics on C mineralization rates and N release. Spruce needles (Picea abies) and leaves of four dominant species (Avenella flexuosa, Calamagrostis villosa, Vaccinium myrthillus and Athyrium alpestre) of understorey vegetation were collected in autumn 2006. Litter was incubated at 0 and 10 °C. CO2 release was regularly measured each 14 days. Amounts of phenolics, available phosphorus, total and extractable C and N, release of NH4+ and NO3- were measured at the beginning, after one and four months of incubation.