Field and laboratory studies were performed to estimate fluxes of the a-ace gases nitrogen monoxide (NO), nitrous oxide (N2O), and methane (CH4) in an organic soil, to determine the microbial processes involved, and to assess how soil water and nitrogen controlled flux rates. Metabolic inhibitors showed microbial nitrification to be the major NO source, regardless of the soil moisture content. Nitrification also produced N 2O, but denitrification losses of this gas from flooded, anaerobic soil were much higher. Up to 26% of nitrified N was converted to NO, but most of this (95%) was consumed microbially before it could escape across the soil surface. The NO-consuming process appeared to be co-oxidation by soil heterotrophs, not coupled to energy production. Organic matter content and CO2 production were therefore good predictors of NO oxidation rates across soil types, and NO oxidation was stimulated by manure addition. / Soil water and nitrogen had nonlinear effects on trace gas fluxes, acting on both production and consumption. Kinetic analysis showed that nitrate was a weak noncompetitive inhibitor, but ammonium a strong competitive inhibitor of soil CH4 oxidation at field fertilization rates. However, spatial and temporal factors complicated fertilization effects on CH4 oxidation in situ. Ammonium was immobilized in surface soil and rapidly nitrified, limiting its inhibitory effect on CH 4 oxidation. Fertilizer N stimulated nitrification and denitrification and therefore gaseous N-oxide production, but other, unexpected fertilizer effects were also observed. Ammonium fertilizer decreased NO oxidation rates. Nitrate and other salts stimulated NO and N2O losses during nitrification, an effect apparently related to soil nitrite accumulation. / The controls exerted on trace gas fluxes by soil water were mediated primarily through diffusion rates. Oxygen diffusion controlled the balance of anaerobic (methanogenesis and denitrification) versus aerobic (CH 4 oxidation and nitrification) processes. Soil moisture content also controlled the diffusion rate of atmospheric CH4 to soil methanotrophs, and the escape of gaseous N-oxides from production sites across the soil surface.

Following the Chernobyl accident in 1986, a range of countermeasures has been developed to reduce the transfer of 137Cs from soil to plant and from the plant into grazing animals. One such countermeasure is the application of potassium to the soil. However, little is known of any side-effects such an application may have on the ecosystem, the longevity of the application and the effectiveness in a range of soil types. An application of potash (KCl) was made to four organic upland soils in Cumbria. England at two application rates of 100 and 200 kg K ha-1 in June 1997 and at a single site in June 1998. Following application. a range of parameters within the ecosystem were recorded, through the collection of monthly samples of sail, vegetation and water samples over a period of fifteen months. The results indicate that the application was effective for at least one year following application, that a lag phase existed between potash application and any effect within each ecosystem and that the duration of this phase was site specific. The results also showed that the countermeasure was effective at all sites and there was little apparent difference between the two application rates. The parameters measured which included soil pH, plant biomass, changes in Cu, K, Mg, Mn and Ca concentrations within the soil and vegetation indicated only a relatively small effect of the application on the ecosystem as a whole. The application can be considered as a viable option for reducing the transfer of 137Cs from soil to plant. The study also shows that the effectiveness of the application is dependent on the measurement used. i.e. concentration ratios, Tag values or a total flux approach. It is argued that the flux approach is the most appropriate basis for comparing the effectiveness of potash as a countermeasure between several sites.

No description available.

No description available.

The focus of this study is on the use of bioremediation, as the primary method of decontamination for a soil contaminated with industrial waste oils. The area from which the samples were taken was used as a disposal site for oily wastewater for a period of more than 20 years. During this time the soil became severely contaminated. The site is approximately 1 acre in area and consists of three distinct soil strata: a solidified petroleum layer, a peat layer and a layer of muck and mud. This soil is approximately 96% organic matter. The purpose of this study is to determine if: given these site characteristics, is bioremediation a feasible option. Three phases were conducted to determine the usefulness of bioremediation in this situation. Phase one focused on the removal of total petroleum hydrocarbons (TPH) through nutrient addition and aeration. Phase two focused on quantifying and characterizing the reductions observed in phase one. Phase three again focused on quantifying and characterizing the reductions observed in phase one. The three phases of the study provided strong evidence that bioremediation was occurring in the soil and therefore, would be a viable means of remediation for a site with similar characteristics.

Les sols organiques cultivés de l'ouest de la Montérégie alimentent une grande part du secteur horticole de la province de Québec. Or, le drainage pour leur mise en culture les rend particulièrement vulnérables à la dégradation et aux pertes de sol. Des scientifiques présument que la moitié de leur dégradation s'expliquerait par l'érosion. Cependant, son intensité réelle est mal connue. Le présent projet de recherche réalisé dans le cadre de la maîtrise en sols et environnement présentait comme objectifs de quantifier l'érosion totale cumulée depuis 1963 en sols organiques cultivés et d'étudier la modulation de son intensité par des mesures de la redistribution spatiale du césium-137. Les taux d'érosion annuels obtenus varient de 0,4 à 8,8 t/ha, alors que ceux estimés initialement varient de 4,1 et 54,6 t/ha. Cependant, la valeur moyenne de 2,9 t/ha (avec un écart-type standard de 2,1 t/ha) obtenue était comparable à celle obtenue dans l'actuelle Étude sur l'état de santé des sols agricoles du Québec réalisée par l'IRDA qui était de 3,6 t/ha (avec un écart-type standard de 4,5 t/ha). Aucune différence significative entre les taux d'érosion annuels n'a pu être détectée au moyen d'analyses de la variance entre les groupes de champs à l'étude. De plus, les analyses comparatives entre les taux d'érosion des sols calculés à partir des teneurs résiduelles en césium-137 par rapport à ceux estimés à l'aide des différents paramètres physico-chimiques ne donnent pas de résultats significatifs. On peut émettre l'hypothèse que la part des pertes de sol par érosion serait plus importante que celle présumée au départ. De plus, plusieurs hypothèses sont avancées afin d'expliquer l'absence d'effet et de tendance significative détectée. Enfin, il semble qu'un nouveau modèle d'interprétation des inventaires de césium-137 en pertes de sol par érosion doive être développé pour les sols organiques cultivés et drainés. / The cultivated organic soils of western Montérégie supply a large part of the horticultural sector of the province of Quebec. However, drainage for their cultivation makes them particularly vulnerable to degradation and soil loss. Scientists assume that half of their degradation can be explained by erosion. However, its real intensity is poorly known. The present research project carried out within the framework of the master's degree in soils and environment presented as objectives to quantify the total cumulative erosion since 1963 in cultivated organic soils and to study the modulation of its intensity by measurements of the spatial redistribution of caesium-137. The annual erosion rates obtained vary from 0.4 to 8.8 t/ha, while those initially estimated vary from 4.1 to 54.6 t/ha. However, the average value of 2.9 t/ha (with a standard deviation of 2.1 t/ha) obtained was comparable to that obtained in the current Study on the Health of Agricultural Soils in Quebec carried out by the IRDA which was 3.6 t/ha (with a standard deviation of 4.5 t/ha). No significant difference between the annual erosion rates could be detected by means of analyzes of variance between the groups of fields under study. In addition, the comparative analyzes between the soil erosion rates calculated from the residual caesium-137 contents compared to those estimated using the various physico-chemical parameters do not yield significant results. It can be hypothesized that the share of soil loss by erosion would be greater than presumed initially. In addition, several hypotheses are put forward to explain the lack of effect and significant trend detected. Finally, it seems that a new model for interpreting caesium-137 inventories in soil loss by erosion must be developed for cultivated and drained organic soils.

Cette étude a permis d'évaluer les quantités d'azote et de phosphore potentiellement minéralisables dans 34 sols organiques cultivés du Sud-Ouest du Québec. Les sols ont libéré en moyenne de 380 kg N ha-1 an-1 et moins de 2 kg P ha-1 an?1. Ils ont été classés en deux groupes de minéralisation. Un seuil critique de minéralisation de 0,8 mg N kg-1 j-1 correspondant à une teneur en carbone de 372 g kg-1 et à un rapport C/N maximal de 30 classait les sols avec un taux de succès de 85 %. Un seuil de minéralisation de 0,04 mg P kg-1 j.-1 correspondant à une teneur en carbone critique de 425 g C kg-1 classait les sols avec un taux de succès de 94 %. En serre, des plants de ray-grass prélevaient jusqu'à 3 fois plus d'azote sur certains sols très minéralisateurs que sur des sols pauvres. La richesse en phosphore des sols a conduit à une absence de réponse à la fertilisation.

No description available.

Three drainage experiments were conducted on a newly developed organic soil where three cultural methods were superimposed. Measurements of carrot yields, subsidence, water table fluctuations, subsurface drain performance, hydraulic conductivity and soil bulk density were made. Rotovating the soil produced higher carrot yields than plowing or disking during the first year. The seven-year subsidence totalled 515 mm and depended mostly on organic soil depth. Hydraulic conductivity values did not change after five years of drainage. Bulk density of the top 0.20 m increased by 71% in 6 years, whereas the values down the profile increased between 3.3 and 16.2%. / The effect of two water table depths (WTD), 0.6 and 0.9 m, in an organic soil on soil water tension, subsidence swelling and carrot yields was studied in undisturbed cores in the greenhouse. Carrot yields were reduced by the 0.9 m WTD. Subsidence with the 0.9 m WTD was more than double that of the 0.6 m WTD. Raising the water table near the surface caused the soil to swell. / Hydraulic conductivity, bulk density, fiber content and drainable porosity were measured in undisturbed organic soil profiles. Values from all four properties decreased with increasing depth.

Made available in DSpace on 2015-03-26T13:53:20Z (GMT). No. of bitstreams: 1 texto completo.pdf: 4624932 bytes, checksum: 032145184c6e6017e7436a55ed7bdf04 (MD5) Previous issue date: 2011-07-26 / The northern region of Minas Gerais, despite adverse conditions, concentrates a significant number of Settlement Projects (PA) implemented by the National Institute of Colonization and Agrarian Reform (INCRA), containing in their areas, large remnants of the Cerrado and Palm swamps, especially PA São Francisco. The existence of this environment is seen as a special attraction, as compared to the environmental conditions of its environment, this environment has more favorable conditions for the use, despite being protected by legislation, which can lead to a sharp degradation process. Currently, there has been a new conception of the agrarian reform process, overlapping the idea of mere division of land to farmers so as to be seen as a process that must be planned, serving as an instrument for social rehabilitation and reorganization of rural areas, being that the use of environmental stratification may be considered a valid tool in this process, since you can associate information with pedogeomorphologically the interrelationships of the various geo-environmental farmers associated with the Settlement. Before the creation of PA São Francisco, the squatters were unrestricted use of the soil of paths, but after the institutionalization of land, environmental agencies began to monitor and curb the use of Palm swamps, creating an environmental conflict. So they have as initial hypotheses that the lack of environmental licensing prevented the development of PA São Francisco, the largest land use in Palm swamps is due to the high content of organic matter and available water in this environment, creating a heavy dependence socio-economic on the Palm swamps; agricultural use over the years, changed negatively and differently, the quality/quantity of soil organic matter "organic" Palm swamps. In this context, this study aimed at identifying and characterizing the different geoenvironments associated with PA San Francisco and its interfaces with the resettled families, analyzing the soil aspects, the implications of the use and importance of each geoenvironment for resettled families. As a result, have the PA São Francisco can be broken down into 06 geoenvironments, chapadas arenosas; chapadão de cimeira; bordas e escarpas metapelíticas; rampas coluviais; escarpas areníticas e veredas e vazantes hidrófilas , characterized as being in poor soils acids and nutrients. Regarding the assumptions listed, it was concluded that the length of INCRA in obtaining the environmental permit, intervened decisively in the development of PA as well as soil conditions that the PA São Francisco is submitted. Thus, one must understand not only the lack of environmental licensing hindered the development of this PA, but rather a lack of planning in getting the property and interfered with its implementation in the failure of this enterprise. As for the hypothesis that deals with land use on the environment path for settlers and their interfaces with that environment, we accept the hypothesis, insofar as these soils with the organic matter content, with great capacity to retain water, can produce food, despite their poverty nutrition, crop production with less demanding and suitable for the parameters of their producers. Finally, it was noted that agricultural activity interfered mainly with the quality of organic matter, but not significantly in most soils and organic geoenvironment Vereda e Vazantes hidrófilas , being explicit, which is degrading this environment is the erosion started with reforestation and then with the opening of roads and other changes in geoenvironment. / A região norte de Minas Gerais, apesar das condições adversas, concentra número expressivo de Projetos de Assentamento (PA) implantados pelo Instituto Nacional de Colonização e Reforma Agrária (INCRA), contendo em suas áreas, grandes remanescentes do bioma Cerrado e de veredas, especialmente no PA São Francisco. A existência deste ambiente é tida como um atrativo especial, pois, comparativamente às condições ambientais do seu entorno, este ambiente possui condições mais favoráveis para a utilização, apesar de ser protegido por legislação, o que pode levar a um acentuado processo de degradação. Atualmente, tem-se observado uma nova concepção do processo de reforma agrária, sobrepondo a idéia de mera divisão de terra para agricultores, passando a ser vista como um processo que deve ser planejado, servindo como instrumento social de reabilitação e reorganização de áreas rurais, sendo que, o uso da estratificação ambiental pode ser considerada uma ferramenta válida neste processo, já que se pode associar as informações pedogeomorfológicas com as inter-relações dos agricultores com os diversos geoambientes associados ao Projeto de Assentamento. Antes da criação do Projeto de Assentamento São Francisco, os posseiros faziam uso sem restrição dos solos de veredas, mas depois da institucionalização da terra, os órgãos ambientais começaram a fiscalizar e coibir o uso deste geoambiente, gerando um conflito ambiental. Assim, têm-se como hipóteses iniciais que a inexistência do licenciamento ambiental impediu o desenvolvimento do PA São Francisco; a maior utilização dos solos do geoambiente Vereda se deve ao elevado teor de matéria orgânica e água disponível neste ambiente, criando uma grande dependência sócio-econômica dos assentados a este geoambiente e; o uso agrícola, ao longo dos anos, alterou negativamente e de modo diferenciado, a qualidade/quantidade da matéria orgânica dos solos orgânicos do ambiente Vereda. Neste contexto, esta pesquisa teve por objetivo geral identificar e caracterizar os diferentes geoambientes associados ao PA São Francisco e suas interfaces com as famílias assentadas, analisando os aspectos pedológicos, as implicações do uso e a importância de cada geoambiente para as famílias assentadas. Como resultados, têm-se que o PA São Francisco pode ser discriminado em 06 geoambientes, a saber: chapadas arenosas; chapadão de cimeira; bordas e escarpas metapelíticas; rampas coluviais; escarpas areníticas e veredas e vazantes hidrófilas, sendo caracterizados como solos pobres em nutrientes e ácidos. Quanto às hipóteses elencadas, concluiu-se que a morosidade do INCRA em obter o licenciamento ambiental, interferiu de forma decisiva no desenvolvimento do PA, bem como as condições edáficas que o PA São Francisco está submetido. Assim, deve-se entender que não somente a falta de licenciamento ambiental entravou o desenvolvimento deste Projeto de Assentamento, mas, sobretudo a falta de um planejamento na obtenção do imóvel e sua implantação interferiu no insucesso deste empreendimento. Quanto à hipótese que trata do uso do solo do ambiente vereda pelos assentados e suas interfaces com este ambiente, se aceita a hipótese, na medida em que esses solos com esse teor de matéria orgânica, com grande capacidade de retenção de água, conseguem produzir alimentos, apesar da sua pobreza nutricional, cultivos menos exigentes e com produções satisfatórias para os parâmetros dos seus produtores. Por fim, percebeu-se que a atividade agrícola interferiu principalmente na qualidade da matéria orgânica, mas não de forma significativa na maioria dos solos orgânicos do geoambiente Vereda e Vazantes Hidrófilas; ficando explícito que, o que vem degradando este ambiente é o processo erosivo iniciado com o reflorestamento e, depois, com as aberturas das estradas e alterações nos outros geoambientes.