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Doohan, Thomas James. "Drivers of Soil Organic Matter Stabilization across Ohio." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1597941993038872.
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Poirier, Vincent. "Investigating the mechanisms of soil organic matter stabilization in a clayey soil of the St-Lawrence lowlands, Québec, Canada." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104764.
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Soil organic matter (SOM) is a key element in soil quality and productivity, and represents the biggest C pool of the terrestrial biosphere. Understanding soil organic carbon (SOC) retention mechanisms is necessary to address their role as potential C sink, and ensure their quality and productivity for future generations. The objective of this research was to examine, under controlled conditions, the stabilization of newly added C and N coming from crop residues in topsoil and subsoil horizons of a heavy clay soil from the St-Lawrence Lowlands. Topsoil (0-20 cm depth, 31.3 g SOC kg-1 soil) and subsoil (30-70 cm depth, 4.5 g SOC kg-1 soil) were incubated (25ºC, -38 kPa, C/N = 10) for 51 d with increasing amounts (from 0 to 40 g C kg-1 soil) of 13C-15N-labelled corn residues. Carbon mineralization was greater in topsoil than subsoil, but comparable amounts of residue-C were retained in both soils, on a whole soil basis. This suggests that the extra C lost from the topsoil came from the mineralization of autochthonous SOC. Preferential retention of residue-derived C and N occurred in large macroaggregates (>1000 µm) in the subsoil, and in small macroaggregates (250-1000 µm) in the topsoil. Macroaggregate enrichment in residue-derived C and N occurred simultaneously through small-scale adsorption (< 50 µm) and large-scale occlusion (>250 µm). Sequential density fractionation of soil coupled with X-ray diffraction mineralogical analysis revealed a greater proportion of autochthonous and residue-derived C and N associated with soil minerals in subsoil than topsoil. Subsoil organo-mineral complexes were enriched in residue-derived N, indicating preferential adsorption of nitrogenous compounds onto unsaturated mineral surfaces in the early stages of organo-mineral complexes formation. In conclusion, topsoil and subsoil horizons of a heavy clay soil from Eastern Canada can accumulate substantial amounts of residue-derived C and N, with greater potential for C and N sequestration in stable organo-mineral complexes in subsoil than topsoil.La matière organique du sol (MOS) assure la qualité et la productivité du sol et représente le plus grand réservoir de C de la biosphère terrestre. Comprendre les mécanismes de rétention du carbone organique du sol (COS) s'avère essentiel pour évaluer le potentiel des sols à agir comme puits de C et pour assurer leur qualité et leur productivité futures. La présente recherche visait à évaluer, en conditions contrôlées, la stabilisation du C et de l'N provenant de résidus de culture nouvellement incorporés dans les horizons superficiel et profond d'un sol argileux des Basses-Terres du St-Laurent. Des échantillons de sol des horizons superficiel (0-20 cm, 31.3 g COS kg-1 sol) et profond (30-70 cm, 4.5 g COS kg-1 sol) ont été incubés (25ºC, -38 kPa, C/N=10) pendant 51 jours avec des doses croissantes (0 à 40 g C kg-1 sol) de résidus de maïs enrichis en 13C et 15N. La minéralisation du C était plus importante dans l'horizon superficiel que dans l'horizon profond, alors que la quantité de nouveau C retenue dans le sol entier était similaire dans les deux horizons, suggérant ainsi qu'une minéralisation du COS autochtone est survenue. Le C et l'N des résidus ont été retenus préférentiellement dans les grands macroagrégats (>1000 µm) dans l'horizon profond, mais dans les petits macroagrégats (250-1000 µm) dans l'horizon superficiel. L'enrichissement des macroagrégats en C et N nouveaux s'est produit par adsorption à petite échelle (< 50 µm) et par occlusion à grande échelle (>250 µm) simultanément dans le sol. Le fractionnement densimétrique couplé à l'analyse minéralogique du sol a révélé qu'une proportion plus grande du C et de l'N autochtones et provenant des résidus était associée aux phases minérales dans l'horizon profond que dans l'horizon superficiel. Les complexes organo-minéraux de l'horizon profond étaient enrichis en N autochtone et provenant des résidus, ce qui indique une adsorption préférentielle des composés azotés sur les surfaces minérales non saturées lors des premières étapes de formation des complexes organo-minéraux. Ainsi, les horizons superficiel et profond étudiés peuvent tous deux accumuler davantage de C et d'N provenant des résidus, mais le potentiel de séquestration du C et de l'N par association organo-minérale stable s'avère plus important dans l'horizon profond que dans l'horizon superficiel.
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Andruschkewitsch, Rouven [Verfasser]. "Effects of different tillage treatments on labile soil organic matter pools and stabilization processes / Rouven Andruschkewitsch." Kassel : Universitätsbibliothek Kassel, 2013. http://d-nb.info/103872354X/34.
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Mikutta, Robert. "Stabilization of organic matter in the acid soil environment : importance of mineral phases and involved mechanisms /." Tönning ; Lübeck Marburg : Der Andere Verl, 2007. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016441507&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Ndossi, Emanueli Mathayo [Verfasser]. "Composition, degradation and stabilization of soil organic matter along an elevation gradient of Mount Kilimanjaro / Emanueli Mathayo Ndossi." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/122410031X/34.
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Schmidt, Jana [Verfasser], Beate [Gutachter] Michalzik, and Francois [Gutachter] Buscot. "Stabilization and dynamics of soil organic matter in response to long-term mineral and organic fertilization / Jana Schmidt ; Gutachter: Beate Michalzik, Francois Buscot." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/1205884424/34.
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Vázquez-Ortega, Angélica. "Coupled Transport, Fractionation and Stabilization of Dissolved Organic Matter and Rare Earth Elements in the Critical Zone." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301696.
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It is important to understand the processes that influence the critical zone (CZ) evolution to ensure its sustainability. This thesis reports on laboratory and field experiments designed to measure the behavior of biogenic and lithogenic chemical species and their interaction in the CZ from column to pedon to catchment scales. We postulated that interactions between organic matter and rock-derived metals drive coupled processes of carbon stabilization and chemical weathering and denudation in the Jemez River Basin Critical Zone Observatory (JRB-CZO). First, we observed that secondary mineral coatings (Al and Fe (oxy)hydroxides) on primary silicate surfaces play a major role in sequestering aromatic and "humified" dissolved organic matter (DOM) into sorbate form, significantly retarding their subsurface transport. Further, reinfusion to OM-reacted-porous-media of a different DOM source resulted in exchange reactions consistent with a zonal model of OM adsorption at mineral surfaces. This dissertation also aimed to examine the influence of water and DOM fluxes on the CZ weathering processes. Rare earth elements (REE) were selected because of their coherent trends in reactivity toward organic ligands common to soils. Specifically, trends in REE fractionation were explored for their utility to inform on biogeochemical weathering processes in forested terrain in the JRB-CZO. Mineral weathering mechanisms are expected to differentially influence REE release, fractionation, and transport and the relative importance of such processes should be reflected in REE signatures of bulk soil, pore and surface waters. Our studies showed: (1) REE depletion trends with depth in bulk soils are correlated with topographically-induced variation in water and dissolved organic carbon (DOC) flux (reflected in negative correlations between total water and C fluxes) and solid phase REE concentrations measured at the same depths; (2) REE and DOC concentrations in stream waters were strongly correlated during snowmelt periods of high discharge, consistent with REE complexation and mobilization in association with organic ligands during shallow subsurface flow; (3) preferential sequestration of Eu occurs during formation of secondary Mn(IV)-oxides, explaining patterns of Eu enrichment in bulk soils; and (4) the incremental increase in positive Ce-anomalies with depth in bulk soils are apparently controlled by adsorption/co-precipitation with secondary Fe-(oxy)hydroxide minerals.
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Bimüller, Carolin Verfasser], Ingrid [Akademischer Betreuer] [Kögel-Knabner, and Heinz [Akademischer Betreuer] Flessa. "From leaf to soil - Nitrogen partitioning and stabilization in soil organic matter / Carolin Bimüller. Gutachter: Ingrid Kögel-Knabner ; Heinz Flessa. Betreuer: Ingrid Kögel-Knabner." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1066985952/34.
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Graf-Rosenfellner, Markus [Verfasser], Martin [Akademischer Betreuer] Kaupenjohann, Martin [Gutachter] Kaupenjohann, and Friederike [Gutachter] Lang. "Soil organic matter in riparian floodplain soils : regionalization of stocks and stabilization processes / Markus Graf-Rosenfellner ; Gutachter: Martin Kaupenjohann, Friederike Lang ; Betreuer: Martin Kaupenjohann." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156274958/34.
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Shahbaz, Muhammad Verfasser], Yakov [Akademischer Betreuer] [Kuzyakov, Andrea [Gutachter] Carminati, Felix [Gutachter] Heitkamp, and Evgenia [Gutachter] Blagodatskaya. "Crop residue decomposition and stabilization in soil organic matter / Muhammad Shahbaz ; Gutachter: Andrea Carminati, Felix Heitkamp, Evgenia Blagodatskaya ; Betreuer: Yakov Kuzyakov." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1125712996/34.
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Tamrat, Wuhib Zewde. "Sequestration of soil organic matter by nanominerals : experimental approach to the formation of organo-mineral complex from biotite alteration products." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0624.
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Les interactions organo-minérales contrôlent la stabilisation de la matière organique du sol. Les nanominéraux, résultant de l'altération continue des minéraux, précipitent à partir d'espèces ioniques à leur surface. Les derniers travaux de simulation en laboratoire se sont focalisés sur les nanophases de Fe et Al. Dans ce travail, des simulations en laboratoire ont été réalisées sur les processus d'altération de la biotite et les néoformations résultantes, après hydrolyse d’espèces dissoutes d'un système Si Fe Al Mg et K, en présence et en absence de C. La structure des phases a été caractérisée par TEM- EDX et Fe-EXAFS.En l'absence de C, des nanominéraux amorphes de 10-60nm sont formés, la composition étant contrôlée par le pH en fin d'hydrolyse. A pH4.2 et 7, leur composition est dominée par Fe, dont la polymérisation est perturbée par Al Si Mg et K. Inversement, à pH5, la polymérisation du Fe est limitée par la précipitation de grandes quantités de Si. En présence de C, les complexes organo-minéraux synthétisés sont des particules amorphes de 2-200nm. Leur taille augmente avec la teneur croissante en C jusqu'à un ratio métal/C de 1. La précipitation engendre 2 familles: (1) les petites particules chimiquement similaires à la solution de lixiviat; (2) les plus grosses fortement contrôlées par la teneur de C. La composition de ces dernières est dominée par Si lorsque C est faible, et par Fe lorsque C est élevé. Le changement de chimie entre les particules plus petites et plus grandes ainsi que le rôle de Si sont importants mais souvent négligés. Ainsi, ces résultats éclairent l'effet des variations de C sur l'affinité des espèces inorganiques dans les systèmes naturelsOrgano-mineral interactions, due to the high reactivity of nanominerals, play a major role in soil organic matter stabilization. Nanominerals, which are the result of the continuous alteration of minerals, precipitate from ionic species at the mineral solution interface. In literature, only Fe and Al get emphasis with regard to batch-synthesized nanomineral studies. In this work, laboratory simulations were carried out on the post biotite alteration processes and the resulting neoformations after hydrolysis of the dissolved species from a Si Fe Al Mg and K system, in the presence and absence of C. New phases were characterized by TEM-EDX and EXAFS at the Fe K-edge.In C absence, 10-60nm sized amorphous nanominerals are formed whose composition is controlled by pH at the end of the hydrolysis. For pH4.2 and 7 phases, composition is dominated by Fe, whose polymerization is hindered by Al, Si, Mg and K. Conversely, at pH5, the overall presence of Fe is counteracted by precipitation of high amounts of Si. In C presence, precipitates are amorphous 2-200nm sized particles. This size increases with increasing C presence until a molar Metal:C=1. Precipitation resulted into two distinct size ranges. Smaller particles chemically resemble the leachate solution, while for larger particles it is influenced by C concentration. Composition of larger particles is dominated by Si at low C compositions while by Fe at higher ones. Interesting is the change in chemistry between smaller and larger particles as well as the role of Si often overlooked in other studies. Therefore, these results emphasize on effect of C variations on affinity of inorganic species in natural systems
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Saenger, Anaïs. "Caractérisation et stabilité de la matière organique du sol en contexte montagnard calcaire : proposition d'indicateurs pour le suivi de la qualité des sols à l'échelle du paysage." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENS010/document.
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Les sols de montagne représentent d'importants réservoirs de carbone (C) potentiellement vulnérables aux changements climatiques et changements d'usage qui les affectent de manière amplifiée. Or la grande variabilité de ces milieux, leur faible accessibilité ainsi que le manque d'outils de mesure appropriés limitent nos connaissances qui restent aujourd'hui très fragmentaires en ce qui concerne les stocks, la chimie et la réactivité du carbone organique des sols (COS). Ces informations sont pourtant nécessaires pour appréhender l'évolution de ces sols et de leur C dans ce contexte de changements globaux. Les objectifs de ce travail de thèse étaient (i) d'accéder à une meilleure compréhension de la nature, de la stabilité et de la vulnérabilité du COS dans une mosaïque d'écosystèmes des Préalpes calcaires (massif du Vercors), (ii) de rechercher des outils de caractérisation rapides et fiables adaptés à l'étude et au suivi du COS à l'échelle du paysage, et enfin (iii) de proposer des indices pour l'évaluation et le suivi de la qualité des sols en milieu de montagne. Dans un premier temps, nous avons testé l'application de la pyrolyse Rock-Eval pour l'étude du COS à grande échelle sur un ensemble d'unités écosystémiques. Nous avons ensuite comparé la pyrolyse Rock-Eval à deux techniques classiques d'étude de la matière organique du sol (MOS) : le fractionnement granulodensimétrique de la MOS et la spectroscopie moyen infrarouge. Ces approches analytiques couplées nous ont permis de quantifier les stocks de C à l'échelle de la zone d'étude et d'expliquer la stabilité et la vulnérabilité du COS sous des angles variés. Les facteurs responsables des patrons observés dans les différentes unités écosystémiques sont discutés. Ce travail a également confirmé la pertinence de l'outil Rock-Eval pour répondre aux objectifs fixés. Parallèlement, des approches biologiques nous ont permis d'évaluer l'importance de la composante microbienne dans ces sols. Enfin, des indices évaluant le statut organique des sols (stockage de COS, fertilité des sols, vulnérabilité du COS) sont proposés pour constituer des outils de gestion et d'aide à la décisionMountain soils are major reservoirs of carbon (C), potentially vulnerable to climate and land use changes that affect them significantly. However, the great variability of these soils, their limited accessibility and the lack of appropriate measurement tools restrict our knowledge. Today, our comprehension of the biogeochemistry of mountain soils remains very incomplete regarding stocks, chemistry and reactivity of soil organic carbon (SOC). Yet this information is necessary to understand the evolution of soil carbon in the current context of global change. The objectives of this work were (i) to gain a better understanding of the nature, stability and vulnerability of SOC in a mosaic of ecosystems in a calcareous massif in the Alps (Vercors massif), (ii) to search for fast and reliable characterization tools, suitable for the study and monitoring of COS at the landscape scale, and (iii) to propose indicators for the assessment and monitoring of soil quality in mountain regions. As a first step, we tested the application of Rock-Eval pyrolysis for the study of COS at large-scale on a set of ecosystem units. Then, we compared the Rock-Eval approach to two conventional techniques for soil organic matter (SOM) study: the particle-size fractionation of SOM, and the mid-infrared spectroscopy. These coupled analytical approaches allowed us to quantify C stocks across the study area, and explain the stability and the vulnerability of COS at various angles. Factors responsible for the patterns observed in the different eco-units are discussed. This work also confirmed the relevance of the Rock-Eval tool to achieve our previous objectives. Biological approaches allowed us to assess the significance of microbial pool in these soils. Finally, indices assessing the status of SOM (SOC storage, soil fertility, vulnerability COS) were proposed and constituted interesting management tools for decision-makers
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Nilsson, K. Sofia. "Modelling soil organic matter turnover /." Uppsala : Dept. of Ecology and Environmental Research, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s326.pdf.
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Yapa, P. I. "Soil structural quality and soil organic matter : can the level of soil organic matter be taken as an indicator in assessing soil structural quality?" Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271592.
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Yusran, Fadly Hairannoor. "Soil organic matter decomposition : effects of organic matter addition on phosphorus dynamics in lateritic soils." University of Western Australia. School of Earth and Geographical Sciences, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0120.
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[Truncated abstract] Relationships between the persistence of organic matter added to soil, the dynamics of soil organic carbon (C) and phosphorus (P) were examined in four experiments on lateritic soils of Western Australia. The main objective was to quantify the release of P following organic matter application in soils which have high P adsorbing capacity. Another objective was to confirm that due to its recalcitrant materials, the effect of peat lasted longer in soil than other sources of organic matter in terms of increasing plant-available P fractions. Three experiments were conducted under glasshouse conditions for various lengths of time, with nine- to twelve-month incubations to investigate these hypotheses. As expected, organic matter with lower C:N ratios than peat (lucerne hay) decomposed more rapidly compared with peat, and the most active mineralisation took place within the first three months of incubation. Soil organic-C (extracted by 0.5 M K2SO4) had a significant positive correlation with P extracted with 0.5 M NaHCO pH 8.53. For a higher application rate (120 ton ha-1), peat was better than wheat straw and lucerne hay in increasing extractable bicarbonate-P concentrations in soil, especially at incubation times up to 12 months. Throughout the experiment, peat was associated with a steady increase in all parameters measured. In contrast to peat, nutrient release from lucerne hay and wheat straw was rapid and diminished over time. There was a tendency for organic-C (either in the form of total extractable organic-C or microbial biomass-C) to steadily increase in soil with added peat throughout the experiment. Unlike wheat straw and lucerne hay, extractable organic-C from peat remained in soil and there was less C loss in the form of respiration. Therefore, peat persisted and sequestered C to the soil system for a longer time than the other source of organic matter. Freshly added organic matter was expected to have a greater influence on P transformation from adsorbed forms in lateritic soils than existing soil organic matter. By removing the existing soil organic matter, the effect of freshly applied organic matter can be determine separately from that of the existing soil organic matter for a similar organic-C content. In order to do this, some soil samples were combusted up to 450° C to eliminate inherent soil organic matter. The release of P was greater when organic-C from fresh organic matter was applied to combusted soils than in uncombusted soils that contained the existing soil organic matter. The exception only applied for parameters related to soil micro-organisms such as biomass-C and phosphatase. For such parameters, new soil organic matter did not create conditions favourable for organisms to increase in activity despite the abundance of organic matter available. More non-extractable-P was formed in combusted soils compared to bicarbonate-P and it contributed to more than 50% of total-P. As for the first experiment, peat also showed a constant effect in increasing bicarbonate extractable-P in the soil
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Zakharova, Anna. "Soil organic matter dynamics: influence of soil disturbance on labile pools." Thesis, University of Canterbury. School of Biological Sciences, 2014. http://hdl.handle.net/10092/9944.
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Soils are the largest pool of carbon (C) in terrestrial ecosystems and store 1500 Gt of C in their soil organic matter (SOM). SOM is a dynamic, complex and heterogeneous mixture, which influences soil quality through a wide range of soil properties. Labile SOM comprises a small fraction of total SOM (approximately 5%), but due to its rapid turnover has been suggested to be most vulnerable to loss following soil disturbance. This research was undertaken to examine the consequences of soil disturbance on labile SOM, its availability and protection in soils using the isotopic analysis of soil-respired CO₂ (δ¹³CO₂).
A range of soils were incubated in both the short- (minutes) and long-term (months) to assess changes in labile SOM. Shifts in soil-respired δ¹³CO₂ over the course of soil incubations were found to reflect changes in labile substrate utilisation. There was a rapid depletion of δ¹³CO₂ (from a starting range between -22.5 and -23.9‰, to between -25.8 and -27.5‰) immediately after soil sampling. These initial changes in δ¹³CO₂ indicated an increased availability of labile SOM following the disturbance of coring the soil and starting the incubations. Subsequently δ¹³CO₂ reverted back to the initial, relatively enriched starting values, but this took several months and was due to labile SOM pools becoming exhausted.
A subsequent study was undertaken to test if soil-respired δ¹³CO₂ values are a direct function of the amount of labile SOM and soil physical conditions. A range of pasture soils were incubated in the short-term (300 minutes), and changes in soil-respired δ¹³CO₂ were measured along with physical and chemical soil properties. Equilibrium soil-respired δ¹³CO₂, observed after the initial rapid depletion and stabilisation, was a function of the amount of labile SOM (measured as hot water extractable C, HWEC), total soil C and soil protection capacity (measured as specific soil surface area, SSA). An independent experimental approach to assess the effect of SSA, where labile SOM was immobilised onto allophane – a clay mineral with large, active surface area – indicated limited availability of labile SOM through more enriched δ¹³CO₂ (in a range between -20.5 and -20.6 ‰) and a significant (up to three times) reduction in HWEC.
In the third study, isotopic measurements were coupled with CO₂ evolution rates to directly test whether equilibrium soil-respired δ¹³CO₂ can reflect labile SOM vulnerability to loss. Soils were sampled from an experimental tillage trial with different management treatments (chemical fallow, arable cropping and permanent pasture) with a range of C inputs and soil disturbance regimes. Soils were incubated in the short- (300 minutes) and long-term (600 days) and changes in δ¹³CO₂ and respiration rates measured. Physical and chemical fractionation methods were used to quantify the amount of labile SOM. Pasture soils were characterised by higher labile SOM estimates (HWEC; sand-sized C; labile C respired during long-term incubations) than the other soils. Long-term absence of plant inputs in fallow soils resulted in a significant depletion of labile SOM (close to 50% based on sand-sized C and HWEC estimates) compared with pasture soils. The values of δ¹³CO₂ became more depleted in 13C from fallow to pasture soils (from -26.3 ‰ to -28.1 ‰) and, when standardised (against the isotopic composition of the solid soil material), Δ¹³CO₂ values also showed a decrease from fallow to pasture soils (from -0.3 ‰ to -1.1 ‰). Moreover, these patterns in isotopic measures were in strong agreement with the amount of labile SOM and its availability across the soils, and were best explained by the isotopic values of the labile HWEC fraction.
Collectively, these results confirm that labile SOM availability and utilisation change immediately after soil disturbance. Moreover, isotopic analysis of soil-respired CO₂ is a powerful technique, which enables us to probe mechanisms and examine the consequences of soil disturbance on labile SOM by reflecting its availability and the degree of SOM protection.
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Burns, Nancy Rosalind. "Soil organic matter stability and the temperature sensitivity of soil respiration." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/9922.
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Soil respiration is an important source of atmospheric CO2, with the potential for large positive feedbacks with global warming. The size of these feedbacks will depend on the relative sensitivity to temperature of very large global pools of highly stable soil organic matter (SOM), with residence times of centuries or longer. Conflicting evidence exists as to the relationships between temperature sensitivity of respiration and stability of SOM, as well as the temperature sensitivity of individual stabilisation mechanisms. This PhD considers the relationship between different stabilisation mechanisms and the temperature sensitivity of SOM decomposition. I used physical fractionation to isolate SOM pools with a variety of turnover rates, from decadal to centennially cycling SOM, in a peaty gley topsoil from Harwood Forest. Mean residence times of SOM as determined by 14C dating was most strongly affected by depth, providing stability on a millienial scale, while OM-mineral associations and physical protection of aggregates provided stability to around 500 years. Chemical characteristics of organic material in these fractions and whole soils (13C CP-MAS NMR spectroscopy, mass spectrometry, FTIR spectroscopy, thermogravimetric analysis, ICP-OES) indicated the relative contribution of different stabilisation mechanisms to the longevity of each of these fractions. Two long-term incubations of isolated physical fractions and soil horizons at different temperatures provided information about the actual resistance to decomposition in each SOM pool, as well as the temperature sensitivity of respiration from different pools. Naturally 13C-labelled labile substrate additions to the mineral and organic horizons compared the resistance to priming by labile and recalcitrant substrates. Manipulation of soil pore water was investigated as a method for isolating the respiration of SOM from physically occluded positions within the soil architecture. Contadictory lines of evidence emerged on the relative stability of different SOM pools from 14C dating, incubation experiments and chemical characterisation of indicators of stability. This led to the interpretation that physical aggregate protection primarily controls SOM stability within topsoils, while mineral and Fe oxide stability provides more lasting stability in the mineral horizon. Less humified and younger SOM was found to have a higher sensitivity to temperature than respiration from well-humified pools, in contrast to predictions from thermodynamics.
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Christensen, Bent T. "Organic matter in soil : structure, function and turnover /." Tjele : Danish institute of agricultural sciences. Research centre Foulum, 2000. http://catalogue.bnf.fr/ark:/12148/cb388316309.
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Ogden, J. M. "Some effects of afforestation on soil organic matter." Thesis, University of Stirling, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375418.
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Frankki, Sofia. "Association of organic compounds to dissolved and particulate natural organic matter in soils /." Umeå : Dept. of Forest Ecology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200652.pdf.
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Liebmann, Patrick [Verfasser]. "Retention and stabilization of organic matter in forest subsoils / Patrick Liebmann." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://d-nb.info/1238222439/34.
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Wagai, Rota. "Climatic and Lithogenic Controls on Soil Organic Matter-Mineral Associations." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/WagaiR2005.pdf.
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Herrmann, Anke. "Predicting nitrogen mineralization from soil organic matter - a chimera? /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a429.pdf.
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Sequeira, Cleiton Henrique. "Soil Organic Matter Dynamics in Cropping Systems of Virginia's Valley Region." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/37381.
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Soil organic matter (SOM) is a well known indicator of soil quality due to its direct influence on soil properties such as structure, soil stability, water availability, cation exchange capacity, nutrient cycling, and pH buffering and amelioration. Study sites were selected in the Valley region of Virginia with the study objectives to: i) compare the efficiency of density solutions used in recovering free-light fraction (FLF) organic matter; ii) compare different soil organic fractions as sensitive indices of short-term changes in SOM due to management practices; iii) investigate on-farm effects of tillage management on soil organic carbon (SOC) and soil organic nitrogen (SON) stocks; and iv) evaluate the role of SOM in controlling soil available nitrogen (N) for corn uptake. The efficiency of the density solutions sodium iodide (NaI) and sodium polytungstate (SPT) in recovering FLF was the same at densities of 1.6 and 1.8 g cm⁻³, with both chemicals presenting less variability at 1.8 g cm⁻³. The sensitivity of SOM fractions in response to crop and soil management depended on the variable tested with particulate organic matter (POM) being the most sensitive when only tillage was tested, and FLF being the most sensitive when crop rotation and cover crop management were added. The on-farm investigation of tillage management on stocks of SOC and total soil N (TSN) indicated significant increases at 0–15 cm depth by increasing the duration (0 to 10 years) of no-tillage (NT) management (0.59 ± 0.14 Mg C ha⁻¹ yr⁻¹ and 0.05 ± 0.02 Mg N ha⁻¹ yr⁻¹). However, duration of NT had no significant effect on SOC and TSN stocks at 0–60 cm depth. Soil available N as controlled by SOM was modeled using corn (Zea mays L.) plant uptake as response and several soil N fractions as explanatory variables. The final model developed for 0–30 cm depth had 6 regressors representing the different SOM pools (active, intermediate, and stable) and a 𝑅² value of 65%. In summary, this study provides information about on-farm management affects on SOM levels; measurement of such effects in the short-term; and estimation of soil available N as related to different soil organic fractions.Ph. D.
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Sheremata, Tamara W. "The influence of soil organic matter on the fate of trichloroethylene in soil." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0017/NQ44582.pdf.
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Eleki, Krisztina. "Soil management, crop rotations, and biomass removal effects on soil organic matter content." [Ames, Iowa : Iowa State University], 2007.
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Williams, Stephen. "Soil transformations of added organic matter in organic farming systems and conventional agriculture." Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU083669.
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The aim of this work was to assay the effects of previous history of organic amendment to soils in the field on the ability of those soils to mineralise mustard, a non-legume green manure. Soil and 15N labelled mustard mineralisation was followed in laboratory microcosms. Volatilised N was assayed by direct acid trapping of N in glass fibre disks, followed by direct combustion isotope ratio mass spectrometry. Animal manures, green manures and straw added to the soil in the field in the previous season, same season and for 7 years continuously did not significantly affect these soils' ability to mineralise mustard in microcosms. Nitrification and mineralisation were the dominant processes during the first 12 days of incubation. Volatilisation rates were 1000-fold lower than mineralisation or nitrification rates. Mustard N accounted for between 1-3% of the soil mineral N, whereas only a maximum of 0.01% of mustard N was volatilised over 24 days. Soils sampled at different times in the season decomposed mustard at similar rates at stimulated low spring temperatures. Nitrification rate was reduced 5-fold more than the mineralisation rate at 8oC. Straw incorporation for seven years did not affect the subsequent recovery of 15N enriched fertiliser or of 15N from labelled straw, by oil seed rape. 15N labelled fertiliser contributed up to 63% of the winter barley N. The labelled barley straw subsequently contributed 16% of the oil seed rape N in the absence of any applied fertiliser. Ploughing in straw in the autumn, in the absence of applied fertiliser had no yield penalty or effect on crop uptake, and may retain more mineral N in the upper soil layers, lessening the risk of leaching over the winter period. The results obtained here emphasise the importance of additions of organic materials to soil in supplying plant nutrients and minimising nutrient losses.
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Faituri, Mikaeel Y. "Soil organic matter in Mediterranean and Scandinavian forest ecosystems : dynamics of organic matter, nutrients, and monomeric phenolic compounds /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2002. http://epsilon.slu.se/avh/2002/91-576-6320-3.pdf.
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Gruver, Joel Brooks. "Impact of Management and Texture on Soil Organic Matter Fractions." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-12172007-065019/.
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Growing concerns about elevated levels of atmospheric CO2 and associated climate change have increased interest in soil C. While general increases in the adoption of conservation management practices may result in C sequestration, efficient utilization of soil as a C sink will require identification of soils with high potential for sequestration and improved methods of monitoring soil C. The objectives of this research were to: 1) evaluate the historical roots, experimental validation and subsequent impact of the C saturation relationships proposed by Jan Hassink, 2) evaluate the effects of management and texture on aggregation and C fractions using soil from two long term experiments, 3) develop new methods of structural disruption and physical fractionation that address shortcomings in existing methods, 4) evaluate the impact of antecedent C on C and aggregate dynamics and 5) evaluate the simplified MnoxC method proposed by Weil et al. (2003). Collectively, the literature we reviewed did not support broad application of simple C saturation relationships such as those proposed by Hassink but did support selective use of fine mineral content as an indicator of C storage capacity. Results from two incubation experiments demonstrated the modulating effect of antecedent C on soil C and aggregate dynamics following structural disruption and residue addition. Positive effects of residue and structural disruption on aggregation were greatest in soil with low antecedent C. Residue decomposed more rapidly in soil with high antecedent C but had a greater priming effect in soil with low antecedent C. Addition of a 15N labeled nitrate source revealed that immobilization of nitrate-N within microaggregates is a minor process irrespective of structural disruption and antecedent C. Carbon contained in microaggregates within stable macroaggregates from an organic transition experiment was sensitive to C input regime but unrelated to fine mineral content. Strong tillage system effects on C fractions, aggregation and texture (tillage intensity↑ = ↓C, aggregate stability and sand content) were identified in soil from a long term tillage system study. Permanganate oxidizable C (Weil method) was found to be a sensitive indicator of management effects on soil C particularly after correction for non-linearity.
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Bell, Madison. "Developing Statistical and Analytical Methods for Untargeted Analysis of Complex Environmental Matrices." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41626.
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The main objective of this thesis was to develop statistical and analytical methods for untargeted analyses of complex environmental matrices like soil and sediment. Untargeted analyses are notoriously difficult to perform in matrices like soil and sediment because of the complexity of organic matter composition within these matrices. This thesis aimed to (1) Develop and compare extraction methods for untargeted analyses of soil and sediment while also developing data handling and quality control protocols; (2) Investigate novel applications of untargeted analyses for environmental classification and monitoring; and (3) Investigate the experimental factors that can influence the organic matter composition of untargeted extractions. CHAPTER TWO is a literature review of metabolomics protocols, and these protocols were incorporated into a proposed workflow for performing untargeted analysis in oil, soil, and sediment. This thesis contains the first application of untargeted analysis to freshwater lake sediment organic matter (i.e. sedimentomics) in CHAPTER THREE, and this has implications for discovering new biomarkers for paleolimnology (APPENDIX ONE). I demonstrated successful extraction methods for both sedimentomics and soil metabolomics studies in CHAPTER THREE and CHAPTER FIVE, respectively, using the proposed workflow from CHAPTER TWO. I also applied sedimentomics to the classification of lake sediments using machine learning and geostatistics based on sediment organic matter compositions in CHAPTER FOUR; this was a novel application of sedimentomics that could have implications for ecosystem classifications and advance our knowledge of organic matter cycling in lake sediments. Lastly, in CHAPTER FIVE I determined microbial activity, extraction method, and soil type can all influence the composition of soil organic matter extracts in soil metabolomics experiments. I also developed novel quality controls and quantitative methods that can help control these influences in CHAPTER FIVE and APPENDIX THREE. APPENDIX TWO was written in collaboration with multiple researchers and is a review of all “omics” types of analyses that can be performed on soil or sediment, and how methods like the untargeted analysis of soil and sediment organic matter can be linked with metagenomics, metatranscriptomics, and metaproteomics for a comprehensive metaphenomics analysis of soil and sediment ecosystems. In CHAPTER SIX the conclusions and implications for each chapter and overall for this thesis are detailed and I describe future directions for the field. In the end the overall conclusions of this thesis were: 1) Quality controls are necessary for sedimentomics and soil metabolomics studies, 2) Sedimentomics is a valid technique to highlight changes in sediment organic matter, 3) Soil metabolomics and sedimentomics yield more information about carbon cycling than traditional measurements, and 4) Soil metabolomics organic matter extractions are more variable and require more quality controls.
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Wick, Abbey Foster. "Soil aggregate and organic matter dynamics in reclaimed mineland soils." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1400961671&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Sohi, Saran Paul. "Dynamic modelling of soil organic matter using physically defined fractions." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251765.
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Watts, Christopher W. "Interactions between tillage energy soil structural stability and organic matter." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/10529.
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In
agricultural production, disturbance of the soil by cultivation occurs regularly.
Mechanical energy applied in this way can have a adverse effect on soil stability, a
lowering of soil organic matter (S_OM), and a increase in CO2 emissions. These
changes result in unwanted environmental consequences and compromise the ability of
soil to maintain a competitive and sustainable agricultural industry. As agricultural
systems evolve, it becomes important to develop a indication of their sustainability
with
regard to soil structure, well before any serious consequences become apparent.
The am of this work was to quantify the effect of mechanical energy (in particular
tillage) on soil structural stability and the loss of SOM.
New
laboratory techniques were devised in which mechanical energy was applied to a
range of soils at different water contents with measurements made of stability and the
mineralization of SOM. Techniques used for characterising stability involved
measuring mechanically-dispersed clay, cm using a turbid metric technique and the
proportion of water stable aggregates (>250 m). A re-examination of the statistical
theory of brittle fracture showed that soil friability, F1, could be quantised using the
coincident of Variation of tensile-strength of a population of similar sized aggregates.
Specific energies associated with different cultivation practices, were simulated using a
falling weight and results indicated that the sensitivity of soil to mechanical damage
was
essentially zero at soil water contents below the plastic limit (wpL). With increasing
soil water content, sensitivity to destabilization increased sharply. The empirical model
to characterise these phenomena was evaluated under field conditions where the energy
consumption of different tillage implements, operating at different soil water contents,
was measured directly. Good agreement between the level of destabilization measured
in the field and those in the laboratory was obtained at similar specific energy values.
C.W. Watts, 2003. Cranfield University, Silsoe.
The field
experiments also showed that increased levels of cm following tillage were
responsible for stronger and less friable day aggregates. More experiments on a soil
with SOC values ranging from all to 32 g/kg enabled the original model to be refined,
linking cm, SOC and soil water content to disruptive energy. This led to the
development of a index, S, which quantise the sensitivity of soil to destabilization by
mechanical energy inputs and provides a method for identifying soils at risk.
The effect of mechanical energy on the mineralization of SOC was measured using the
falling-weight. Mineralization was characterised by measuring soil respiration using
data-logging, conductinetric respirometers, built to monitor CO2 emissions following
applications of mechanical energy. Changes in respiration were characterised by the
respiration ratio, rr (defied a respiration following the application of energy divided
by basal respiration). Higher values of, rr, were associated with greater energy levels,
particularly on soils with lower SOC. Increased respiration was also measured
following tillage in the field, particularly from soils following tillage at high energy
levels where the effect lasted for several weeks.
In this work three
physically based measures of soil quality (S, F1 and rr) have been
used to
quantify the effects of tillage of different intensities on soil structural stability
and the loss of organic matter. Parameters common to these measures of soil quality are
SOC content, soil-water content and tillage intensity. Results of this work indicate that
organic matter, physically protected by stable soil structures, can b exposed to
mineralization when the structure in destabilized during tillage, particularly a the soil
becomes wetter
(w>w1ºL). The practical consequences of this work concluded that
increasing the levels of SOC, cultivating the soil at water contents below the plastic
limit and a reduced
energy input, provide the best practical approach to maintaining
soil
physical quality. The new methodologies developed here have helped improve
understanding of the effects of mechanical energy on soil structural condition. They
provide a sound basis to answer a range of questions relating to soil physical quality
and the
consequences of different soil management practices for soil behaviour in the
environment, thus enabling the boundaries between good and bad practices to b
better defied.
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Zhou, Jie [Verfasser]. "Mycorrhization and Warming Modulate Soil Organic Matter Stability / Jie Zhou." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1236401581/34.
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Maas, Ellen DvL. "The Cascading Effects of Climate Change on Soil Organic Matter." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492076671912468.
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McCabe, Darren P. M. "Spatial location of active soil bacteria and their association with soil organic matter fractions." Thesis, University of Reading, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559246.
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The heterogeneous maze of water and gas filled pores within the soil forms the habitat for the diverse bacterial component of the soil biota. These microorganisms play an essential role in soil processes, but the specificity of their location and that of their associated substrates within these pores remains to be revealed. This research tested a novel approach to assess the contribution of pore neck size to bacterial diversity in soil, using soil aggregates obtained at increasing depths from a rhizotron under the perennial bioenergy crop Miscanthus x giganteus. The nucleotide analogue bromodeoxyuridine (BrdU) was added to soil aggregates using a model that relates the neck diameter of water-filled pores to the soil water matric potential. The BrdU labels the DNA of actively dividing cells within contrasting pore size ranges which can then be isolated through an optimised procedure. A second experiment assayed for soil- and plant-derived enzymes as indicators for root/rhizosphere activity and substrates present across the course of a growing season. Thirdly, the soil carbon was physically fractionated to investigate soil organic matter dynamics on a seasonal scale, and the potential for Miscanthus to accumulate soil carbon on an annual scale. The results provide the first direct evidence that distinct active bacterial communities form within soil pore classes. Further, communities within small pores (-1 - 30 urn) were more diverse than in large pores (30 - 3000 urn). There was marked seasonal variation in both soil enzyme activities and soil light fractions. The soil under Miscanthus was found to be more porous with more accumulated carbon then a comparable arable soil. In summary, the project emphasises the importance of using an integrated multidisciplinary approach to advance our understanding of soil processes on a micro scale so that we can understand and potentially improve soil functioning at the field scale.
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Franco, André Luiz Custódio. "Soil engineering by macroinvertebrates: controls on soil organic matter storage across land use change." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-26052015-165800/.
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Globally land use change (LUC) with increasing in land use intensity has led to a decrease in soil organic matter (SOM). The reduction of soil C stock across LUC has been accompanied by a destabilization of soil structure and increases the soil erosion susceptibility. The destabilized soil structure is also concomitant with a loss of soil biodiversity and in particular, soil macroinvertebrate community. The focus of this dissertation is the effect of LUC with increasing in land use intensity on soil macrofauna, aggregation and SOM allocation. We hypothesized that LUC reduces soil macrofaunal biodiversity and consequently decreases soil engineering processes, resulting in destabilization of soil structure and impairing the ability of soil to physically protect SOM from decomposition inside stable aggregates, finally leading to depleted SOC stocks across LUC. In order to test these hypotheses, we conducted a field survey in 3 chronosequences of land use comprising native vegetation (NV), pasture (PA), and sugarcane crop (SC) in Central-Southern Brazil. This land use sequence provides a gradient of land use intensity and is projected to add 6.4 Mha of new sugarcane areas in Brazil by 2021. At each sampling point soil blocks of 25 X 25 cm and 5 x 5 cm to 10 cm depth were simultaneously collected from 0-10 cm, 10-20 cm, and 20-30 cm soil layers, for macrofauna isolation and aggregate fractionation, respectively. Within a radius of 6 meters around each sampling point, 12 subsamples were also collected from the same soil layers, and combined for total soil C and N concentration. An average reduction of 89% in the density of the soil macrofaunal community was observed when SC replaces PA, and a loss of 39% in the diversity of macrofauna groups. Our findings showed that, over a range of soil textures (16 - 66% clay), such biodiversity loss was strongly correlated with the destabilization of soil structure across LUC, whereas soil texture was not so. These observations consistently indicate that the abundance of detritivore soil animals, especially earthworms and termites, may be a significant predictor of soil structure transformations across LUC in tropical environments. Moreover, the sharp reduction in the abundance of earthworms was strongly positively correlated with the decrease in intra macroaggregate-associated C. As a result, after more than 20 years of sugarcane crop there were losses of 40 and 35% of C and N stocks, respectively, resulting in a rate of C emission of 1.3 Mg ha-1 yr-1. This C loss primarily occurred in the macroaggregate-associated C, as a result of the faster macroaggregate turnover under SC. In summary, the results presented here provide a mechanistic explanation as to why there is soil C depletion when increasing land use intensity in tropical soils: the huge reduction in the abundance of soil engineering invertebrates after LUC impair the ability of soil to physically protect SOM from decomposition inside stable aggregates, and therefore it is a primary mechanism controlling the soil C stocks\' depletion across LUC.Globalmente mudanças no uso da terra (MUT) com o aumento da intensidade de uso do solo têm levado a uma diminuição da matéria orgânica do solo (MOS). A redução do estoque de C do solo após MUT tem sido acompanhada por uma desestabilização da estrutura do solo e aumento da susceptibilidade a erosão. A desestabilização da estrutura também é concomitante com a perda da biodiversidade do solo e, em particular, da comunidade de macroinvertebrados do solo. O foco deste trabalho é o efeito de MUT com aumento na intensidade de uso do solo sobre a macrofauna do solo, agregação e alocação da MOS. Nossa hipótese é que MUT reduz a diversidade da macrofauna do solo e, conseqüentemente, diminui os processos de engenharia de solo, resultando na desestabilização da estrutura do solo e prejudicando a capacidade do solo para proteger fisicamente a MOS da decomposição dentro de agregados estáveis, finalmente levando a redução dos estoques de C após MUT. Foi realizada uma pesquisa em 3 cronosseqüências de uso da terra que compreendem vegetação nativa (NV), pastagem (PA), e cana-de-açúcar (CA) na região Centro-Sul do Brasil. Esta MUT fornece um gradiente de intensidade de uso do solo e é projetada para adicionar 6,4 Mha de novas áreas de CA no Brasil até 2021. Em cada ponto de amostragem de solo blocos de 25 x 25 cm e 5 x 5 cm a 10 cm de profundidade foram coletados simultaneamente das camadas 0-10 cm, 10-20 cm e 20-30 cm de solo, para isolamento da macrofauna e fracionamento de agregados, respectivamente. Foi observada uma redução média de 89% na densidade da comunidade da macrofauna quando CA substitui PA, e uma perda de 39% da diversidade de grupos. Nossos resultados mostraram que, em um intervalo de texturas do solo (16-66% de argila), tal perda de biodiversidade foi fortemente correlacionada com a desestabilização da estrutura do solo após MUT. Estas observações indicam consistentemente que a abundância de animais detritívoros, especialmente minhocas e cupins, pode ser um preditor significativo de transformações da estrutura do solo em MUT. Além disso, a forte redução na abundância de minhocas foi fortemente e positivamente correlacionada com a diminuição do C alocado intra macroagregados. Como resultado, após mais de 20 anos de cultura de CA houve perdas de 40 e 35% dos estoques de C e N, respectivamente, resultando em uma taxa de emissão de C de 1,3 Mg ha-1 ano-1. Esta perda de C ocorreu principalmente no C associado aos macroagregados, como um resultado da reciclagem mais rápida dos macroagregados sob CA. Em resumo, os resultados aqui apresentados fornecem uma explicação mecanicista a respeito de porque há esgotamento do C do solo quando aumenta-se a intensidade de uso do solo em ambientes tropicais: a enorme redução na abundância de invertebrados \"engenheiros do solo\" após MUT prejudica a capacidade do solo para proteger fisicamente a MOS da decomposição dentro de agregados estáveis, e, portanto, é um mecanismo primário controlando a redução dos estoques de C no solo relacionada a MUT.
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Gibson, Richard W. "The characterisation of soluble organic matter from forest soils." Thesis, University of Aberdeen, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295565.
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The characteristics of water-soluble organic material in soil solutions has been studied extensively 'in situ'. Relatively little attention has focused on isolation of such material, particularly when comparison of a number of samples has been attempted. In this study the water-soluble organic acids leached from the soil horizons beneath eight different tree species were isolated by adsorption onto macroporous resins. Amberlite XAD-8 and XAD-4 resins were used in series therefore two samples, labelled as 'hydrophobic' and 'hydrophilic' acids were obtained. Practical amounts of free organic acids for characterisation purposes were isolated from each resin. Elemental analysis (carbon, nitrogen and sulphur) and acidity (measured by potentiometric titration) reflected the probable state of oxidation of the material. Lower molecular weight material was more abundant with depth. Copper binding ability correlated well with the acidity generally but a group of samples isolated from similar horizons and resin showed high acidity and poor metal binding ability. This was probably due to the inability of the acidic sites to be involved in chelation reactions. Metal binding was measured using gel filtration, dialysis and an ion-exchange method. Chromatography in gel filtration was monitored by direct feed of column effluent into an atomic absorption spectrophotometer, a technique attempted but not used successfully before. The method measured directly metal bound and required only 0.2 mg of sample per determination. For these reasons this method was used for routine analysis whereas dialysis and ion-exchange were only used for comparison purposes. As expected the samples isolated on each resin were very different. Comparison of samples from the horizons showed clearly the increased state of oxidation with depth. It was possible to establish differences in the organic material in the soil horizons on the basis of whether the stands were coniferous or deciduous trees but the similarities between the samples were perhaps equally striking.
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Payan, Zelaya Fidel Adolfo. "Effects of 'Erythrina poeppigiana' pruning residues on soil organic matter in organic coffee plantations." Thesis, Bangor University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420651.
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Florence, Robert J. "Comparing soil testing methods for soil organic matter, lime requirements, and developing a phosphorus soil test correlation." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/18903.
Full textAbstract:
Doctor of PhilosophyDepartment of Agronomy
Dave Mengel
The Kansas State University Soil Testing Laboratory currently uses the Walkley-Black (WB) method for soil organic matter (SOM) estimations, the Shoemaker-Mclean-Pratt (SMP) buffer for lime recommendations, and bases the soybean phosphorus (P) critical value for P fertilizer recommendations off other crops. Hazardous waste is produced from WB and SMP creating a health hazard for workers, and substantial cost for handling and disposal. The substantial increase in land area devoted to soybean creates the need to validate currently assumed soil test P critical value and check the current P recommendations for that crop. Overarching objectives of this dissertation are to find suitable non-hazardous replacements for WB and SMP, and to find the soybean P critical value in Kansas. Three common methods used to estimate SOM are WB, dry combustion (DC), and loss on ignition (LOI). An experiment was set up using 98 Kansas soils to compare WB, scooped and weighed, LOI scooped, and DC weighed. All methods correlated well to each other with LOI to weighed WB, LOI to DC, and WB weighed to DC, having correlation coefficients of 0.97, 0.98, and 0.98, respectively. The lowest variability was observed with DC, followed by WB weighed, LOI, and then WB scooped with average standard deviations of 0.04, 0.13, 0.17, and 0.24, respectively. Two non-hazardous alternatives to the SMP buffer to determine soil lime requirement are the Sikora buffer, and the modified-Mehlich buffer. Sikora’s buffer is designed to mimic SMP. Buffer values alone or Mehlich’s equation may be used to calculate lime requirements. Thirty seven soils with a pH less than 5.8 were incubated at lime rates 0, 2240, 4480, 8960, and 17920 kg ECC ha[superscript]-1. Amount of lime required to reach pHs 6.0, 6.3, and 6.6 was calculated. Mehlich’s equation better predicted lime requirements for all target pHs and buffers than buffer pH alone. The Sikora buffer with Mehlich’s equation provided a better lime estimation than the Mehlich buffer using Mehlich’s equation. A P correlation and calibration study was conducted with soybeans at 23 sites in Eastern Kansas from 2011 to 2014. Soil Mehlich-3 P available P was compared to relative soybean yield at these sites. Soybean P critical value was found to be between 10 and 15 or 11.6 mg kg[superscript]-1 using Cate-Nelson, and linear-plateau models, respectively. A linear response to P and relative yield was observed on soils testing between 3 and 8 mg kg[superscript]-1, but not on higher testing soils.
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Golchin, Ahmad. "Spatial distribution, chemistry and turnover of organic matter in soils." Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phg617.pdf.
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Copies of author's previously published works inserted. Bibliography: leaves 260-299. This thesis describes the concept of organic matter turnover and various methods to measure the decay rates of organic materials in the soil. Methods are developed to separate SOM from different locations within the soil matrix. Free particulate organic matter (POM), located between or outside the soil aggregates is isolated. Occluded POM is disaggregeted by sonification. The compositional differences noted among the three components of SOM are used to describe the changes that OM undergoes during decomposition. The process is followed as organic matter enters the soil, is enveloped in aggregates and is eventually incorporated into the microbial biomass and metabolites then becoming associated with clay minerals.
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Badea, Silviu-Laurentiu. "Association of hydrophobic organic compounds to organic material in the soil system." Licentiate thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-68378.
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Contaminated soils and sediments have been identified as significant secondary sources of organic contaminants. Leaching tests may be useful tools to estimate the mobility of contaminants via the water phase and thereby the risk for groundwater and surface water contamination. The influence of soil composition (peat and clay content) on the leachability was investigated in batch leaching experiments for chemically diverse hydrophobic organic compounds (HOCs: PCP, PAHs, HCB, HCHs, PCBs, and TCDD/Fs). The above mentioned compounds were analyzed by both GC-LRMS (gas chromatography coupled with low resolution mass spectrometry (GC-HRMS) and GC-HRMS (gas chromatography coupled with high resolution mass spectrometry). Also the the leachability of eleven selected PCBs from naturally aged soil (Västervik, Sweden) was investigated in relation to the composition and concentration of dissolved organic matter at different pH (2 to 9), using a pH static test with initial acid/base addition. The the composition and of dissolved organic matter (DOM) at different pH values was explored by FTIR spectroscopy. The results were evaluated by orthogonal projections to latent structures (OPLS). Generally, for all model compounds studies, the Kd-values showed a variability of 2-3 orders of magnitude depending on the matrix composition. The Kd-values of moderately hydrophobic compounds, (e.g. HCHs, PCP and Phe), were correlated mainly with the organic matter content of soil. For more hydrophobic compounds (e.g.BaA, HCB and PCB 47), the leachability decreased as the proportions of OM and clay contents increased. The Kd-values of 1,3,6,8-TCDD and 1,3,6,8-TCDF were positively correlated with peat content but negatively correlated with clay content, while for PCB 153 and PCB 155 the correlations were reversed. The log Kd-values of all target PCBs decreased with increased pH values and the log Kd-values were highly correlated with the concentration of total organic carbon (TOC) in the leachates. The FTIR analysis of DOM showed that the least chlorinated and hydrophobic PCB congeners (i.e. PCB 28) might be associated with the hydrophilic fraction (i.e. carboxylic groups) of DOM. Our study demonstrated how complex interaction between the organic matter, clay components, pH and DOC influences the leachability of HOCs in a compound-specific manner.
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Verheijen, Frank G. A. "On-farm benefits from soil organic matter in England and Wales." Thesis, Cranfield University, 2005. http://hdl.handle.net/1826/1006.
Full textAbstract:
Soil organic carbon (SOC) is increasingly recognised as an important component in the global carbon cycle and as a potential C sequestration pool for mitigation of the enhanced greenhouse effect. Recent appeals have prompted research into the potential of storing C in arable fields and the concomitant impact for on-farm economics. This project was instigated to answer the question “Does soil organic matter (SOM), or its management, provide arable on-farm benefit, in England and Wales?”. A methodological design was developed which integrates social science with soil science. From the National Soil inventory (NSI) database, attainable SOC ranges were estimated for different SOC physiotopes, i.e. landscape units for which the environmental factors governing SOC contents are similar. Significant differences were found, e.g for a dry-sandy physiotope and a wet-clayey physiotope, the ranges were estimated at 0.5-1.6% and 2.0-5.4% SOC (w/w), respectively.
A list of qualified ‘SOM benefit’ indicators was developed using an iterative process involving the scientific literature and interviews with ‘expert farmers’. Perceptions of the indicators were investigated within a stratified random sample of commercial farmers. On balance, farmers perceived that benefits of SOM outweighed the disbenefits (i.e. lodging, weeds, and slugs). N fertiliser reduction, increased yield quantity, and enhanced ease of tillage were recognised as the most valuable benefits. However, the values were low to moderate, and perceived to be influenced substantially by physiotope, crop type, and SOM management type.
Farmers’ perceptions and valuations were investigated for 101 fields on commercial farms, selected from the NSI database to represent the attainable SOC content ranges. No correlations were found between SOC and any performance indicator. The full range of reported performances was found for fields with similar SOC contents. This implied that SOC contents and SOM management may have little importance to on-farm economics when compared to the quality of overall farm management.
These results expose the marginal extent of on-farm benefits from increased SOC contents and SOM management. Implications for future research and policy are discussed.
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Monson, Jessica Laura Bruse. "A characterization of soil organic matter in Holocene paleosols from Kansas." Thesis, The University of Iowa, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1540385.
Full textAbstract:
Carbon isotope studies are commonly used to provide a proxy for past vegetation communities and for evaluating environmental change. Original studies suggested carbon isotope ratios of soil organic matter (SOM) faithfully preserved the isotopic composition of standing vegetation with little or no modification in the pedogenic and shallow burial environment. Recent studies of modern soils and laboratory experiments suggest that this may not necessarily be the case and that degradation of SOM in the burial environment may alter the original C-isotope ratio of bulk SOM. A first step in addressing the issue is to begin to understand the transformations of SOM in the burial environment; of particular interest in this study are transformations involving microbial residues. Sedimentary sequences with stacked buried soils afford the opportunity to study the changes that may occur through time and are especially useful if numerical ages and other environmental proxies are present.
The objective of this study is to thoroughly investigate the composition and quantity of organic matter that has been preserved in the surface and buried soils at the Claussen site, using Fourier Transform Infrared Spectroscopy (FTIR), which provides an estimate for the abundance of organic matter components preserved in each paleosol's SOM. We can trace the fate of bioavailable OM and determine the magnitude of preferential decay of SOM with time by first comparing the composition of bulk SOM to the composition of physically protected carbon, located in soil microaggregates (Christensen, 1992) of the stacked buried soils. The results of this project suggest differences in the composition of paleosol and surface soil SOM that could impact paleovegetation interpretations derived from δ13C values.
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Kiem, Rita. "Characterization of refractory soil organic matter in long-term agroecosystem experiments." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967132630.
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Cooke, James Daniel. "Towards an accurate model of cation binding by soil organic matter." Thesis, Lancaster University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444851.
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Nason, Mark A. "Decomposition of tree leaf litter and formation of soil organic matter." Thesis, Bangor University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409217.
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Barajas-Aceves, Martha. "Soil microbial biomass and organic matter dynamics in metal-contaminated soils." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260604.
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Vizard, Catherine. "Soil organic matter quality and nitrogen dynamics in sustainable cropping systems." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289279.
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Shepherd, Matthew John. "The effect of grazing on soil organic matter decomposition on Dartmoor." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394213.
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