Made available in DSpace on 2017-07-10T17:37:36Z (GMT). No. of bitstreams: 1 Fabio_Steiner.pdf: 1984237 bytes, checksum: dd7fb075cef8a63a4698725e6595b0ed (MD5) Previous issue date: 2010-02-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Potassium uptake by plants, in general, is greater than the initial amount of exchangeable K, indicating that non-exchangeable participate in supplying this nutrient to plants. Thus, this study aimed (a) determine the forms of K total, non-exchangeable K, exchangeable K and K in soil solution, (b) determine the buffering capacity of soil potassium, (c) evaluate the ability of potassium supply native and added to a succession of crops, and (d) evaluate the contribution of different forms of potassium in the soil to supply a succession of crops. In this study two experiments were conducted in a greenhouse at the Center for Agricultural Sciences, State University of West Parana, Marechal Candido Rondon, PR, from October 2008 to november 2009. Surface samples (0-20 cm) of 12 soils collected from different regions of Parana State, were subjected to the addition or not of potassium fertilizer (KCl) and the six successive crops (soy, millet, wheat, beans, soybeans and corn). Plants were grown until approximately 40 days after emergence and determined the dry matter production and K content of In the initial samples and those collected after the second, fourth and sixth batch were certain forms of K total, non-exchangeable, exchangeable and soil solution. The forms of soil K showed a large range of values depending on the source material and the degree of weathering of the soil. Soil texture affected the buffering capacity of potassium (PTK), which presented values between 1.28 and 12.79 (mmolc kg-1)/(mmol L-1)0.5. The soils differed in the ability to supply K to the crops, with an important contribution of non-exchangeable forms in the six crops that ranged from 0 to 17.7% with addition of potassium fertilizer and 44.1% to 72.9% without the addition of potassium fertilizer. After the second crop contents of exchangeable K remained constant with average values of 141 and 36 mg kg-1, with and without the addition of potassium fertilizer, respectively / A absorção de K pelas plantas, em geral, e maior que a quantidade inicial de K trocável, indicando que formas não-trocáveis contribuem no suprimento deste nutriente as plantas. Assim, o presente trabalho teve como objetivos (a) determinar as formas de K total, K não-trocável, K trocável e K na solução do solo; (b) determinar o poder tampão de potássio dos solos; (c) avaliar a capacidade de suprimento de potássio nativo e adicionado a uma sucessão de cultivos; e (d) avaliar a contribuição das diferentes formas de potássio do solo no suprimento a uma sucessão de cultivos. Neste estudo foram conduzidos dois ensaios em casa de vegetação no Centro de Ciências Agrárias da Universidade Estadual do Oeste do Paraná, Marechal Candido Rondon, PR, no período de outubro de 2008 a novembro de 2009. Amostras superficiais (0 20 cm) de 12 solos coletadas em diferentes regiões do Estado do Paraná, foram submetidas a adição ou não de fertilizante potássico (KCl) e a seis cultivos sucessivos (soja, milheto, trigo, feijão, soja e milho). As plantas foram cultivadas ate aproximadamente 40 dias apos a emergência, sendo determinada a produção de matéria seca e o teor de K. Nas amostras iniciais e naquelas coletadas apos o segundo, quarto e sexto cultivo foram determinadas as formas de K total, não-trocável, trocável e na solução do solo. As formas de K do solo apresentaram grande amplitude de valores em função do material de origem e do grau de intemperismo do solo. A textura do solo influenciou o poder tampão de potássio (PTK) que apresentou valores entre 1,28 e 12,79 (mmolc kg-1)/(mmol L-1)0,5. Os solos se diferenciaram na capacidade de suprimento de K aos cultivos, havendo uma contribuição importante de formas não trocáveis durante os seis cultivos que variou de 0 a 17,7% com adição de fertilizante potássico e de 44,1% a 72,9% sem adição de fertilizante potássico. Após o segundo cultivo os teores de K trocável mantiveram-se constantes com valores médios de 141 e 36 mg kg-1, com e sem a adição de fertilizante potássico, respectivamente

The work presented in this Doctoral dissertation concerns the ability of heavy timber structures to passively reduce the fluctuations of the indoor temperature and of the indoor relative humidity, through the dynamic process of heat and moisture storage in wood. We make the hypothesis that the potential offered by the hygrothermal inertia of heavy timber structures is significant, and that it could provide a passive way of regulating the indoor climate. This ultimately could results in a decrease of the energy demand from the Heating, Ventilating and Air Conditioning systems. In this Thesis, the author tries to characterise and quantify the significance of the hygrothermal inertia providing by the heavy timber constructions. The experimental studies contain an in-situ measurement campaign carried out at the Vetenskapsstaden building located in Stockholm and erected in 2001. The results from the test campaign show that a heavy timber construction may contribute to buffer the indoor temperature. A direct quantification of the moisture stored in the wood structure is measured regarding the year-to-year indoor humidity fluctuations. It was however hardly possible to directly quantify the moisture storage potential offered by the structure regarding the day-to-day indoor relative humidity fluctuations because of the low sensitivity of the measuring technique used. In regard to the limitations noticed during the in-situ measurements, laboratory measurements were launched to develop new methods to determine the day-to-day hygric performances of wood exposed indoor. A new method based on the Magnetic Resonance Imaging technology was developed and is intended to provide information about the Moisture Buffer Value measured according to a NORDTEST protocol, and about the moisture distribution in wood with high spatial resolution. The Moisture Buffer Value of untreated Scots pine measured with this method is in accordance with the gravimetric method provided by the NORDTEST protocol. The Moisture Buffer Value of coated Scots pine was also investigated and it is normally assumed that any coatings will decrease the Moisture Buffering Capacity of the structure. The results show however that for specific coating such as waterborne alkali silicate coating, the Moisture Buffering Capacity of the structure may on the contrary be improved. At last, numerical simulations were carried out. They were based upon the extension of a modular simulation environment IDA ICE 3.0, with the implementation of a specific model for heat and moisture transport in a wood. The results obtained pinpoint the highly synergetic effects between the indoor moisture loads, the ventilation rate, the outdoor climate and the moisture interactions with the structure. The outcomes also show that the Moisture Buffering Capacity of a heavy timber structure is appreciable. The structure is able to even out substantially the day-to-day indoor relative humidity fluctuations for a certain range of ventilation rate. / QC 20100825

Les fossés agricoles sont des lieux préférentiels d’écoulement des pesticides à l’échelle du bassin versant depuis les parcelles agricoles vers les masses d’eau avales de surface et souterraines. Du fait de leur capacité de rétention ils sont réputés pouvoir exercer un pouvoir tampon pour limiter la dispersion des pesticides dans l’environnement. Les opérations d’entretien des fossés sont identifiées comme un moyen d’améliorer ce pouvoir tampon. Cependant, la connaissance du pouvoir tampon des fossés en fonction de leurs caractéristiques et de leur entretien est très limitée. L’objectif de ce travail est ainsi de quantifier l’impact des principales pratiques d’entretien sur l’évolution du pouvoir tampon d’une gamme de fossés infiltrants.La démarche suivie repose sur i) une caractérisation expérimentale de l’effet des principales pratiques d’entretien sur l’évolution des propriétés des fossés, ii) une analyse de l’influence de ces propriétés sur deux processus clé modulant la rétention des herbicides : la sorption et l’infiltration, iii) une exploration numérique, conçue sur la base des expérimentations, de l’effet de chaque pratique sur l’évolution annuelle du pouvoir tampon des fossés. Le dispositif expérimental a combiné des observations in situ à l’échelle du fossé élémentaire sur 3 bassins versants et des expérimentations au laboratoire et a concerné l’étude du comportement de 3 herbicides, glyphosate, diuron et isoproturon.Les résultats de ce travail ont mis en évidence que les opérations de brûlis, fauche et désherbage chimique améliorent le pouvoir tampon des fossés par rapport à un fossé non-entretenu alors que le curage le détériore. Ils ont aussi permis d’améliorer notre connaissance des propriétés et de la variabilité des matériaux formant les fossés, de proposer un nouvel indicateur de la capacité de rétention des fossés et d’évaluer des approches de modélisation de la rétention des pesticides par un bief de fossé infiltrant. / By linking cropped fields to downstream groundwater and surface water bodies, farm ditches constitute preferential pathways for pesticide dispersal at the catchment scale. But thanks to their pesticide retention capacity ditches are known for buffering pesticide non-point source pollutions. Ditch management operations were identified as mean to improve ditch buffering capacities. However, little is known about how pesticide retention capacities of ditches vary as a function of ditch properties and management. Accordingly, the objective of this work is to quantify how pesticide retention capacity in a range of infiltrating ditches evolves subsequently to the main management operations.The methodology relies on i) an experimental characterization of the main management operation effects on the evolution of ditch properties, ii) an analysis of how these properties influence two key processes regulating herbicides retention: sorption and infiltration, iii) a numerical exploration, based on the previously mentioned experimentations, of each operation effects on the yearly evolution of pesticide retention capacity of ditches. The experimental design combined in situ observations at the reach scale on 3 catchments as well as laboratory experimentations and concerned the behavior of 3 herbicides, glyphosate, diuron and isoproturon.The results of this works highlighted the fact that burning, mowing and chemical weeding operations increase pesticide retention capacities of the ditches as compared to an unmanaged ditch while dredging deteriorates it. They also allowed us to improve our knowledge on ditch materials properties and variability, to propose a new indicator of ditch retention capacity and to evaluate different modelling approaches of pesticide retention by infiltrating ditches.

Biochar application as a soil additive is gaining global acceptance. In this era of climate change, biochar use for improved soil productivity is not just a sustainable eco-friendly substitute to synthetic fertilizer, but a noble contributor to the fight against climate change. Although biochar has been accredited with some environmental and agricultural benefits, most studies concentrated on agricultural and biowaste products as feedstocks. This research was designed to explore P-enriched modified-Douglas fir biochar potential as a soil additive. Using corn as a test crop, greenhouse studies were performed on acidic sandy soil, comparing phosphorus enriched modified-Douglas fir biochar efficacy to a commercial synthetic triple superphosphate fertilizer and a control treatment. Incubation studies were also performed to evaluate the liming and heavy metal immobilization efficacies. Firstly, P-enriched modified-Douglas fir biochar’s ability to release plant soluble P was investigated. At various P enrichment concentration, soil plant availability P from P enriched modified-Douglas fir biochar treatments differed insignificantly from superphosphate fertilizer treatment. The direct correlations between both K and Mg recoveries with available soil P, suggested P enriched modified-Douglas fir biochar potential to supply multiple plant nutrients. Secondly, the influence of P uptake on plant growth and P use efficiency was examined. The greater agronomic P use efficiency obtained in P enriched modified-Douglas fir biochar (~32 kg kg-1) than the triple supper phosphate fertilizer (~17 kg kg-1) treatment confirmed P enriched modified-Douglas fir biochar potential as a multiple nutrient released soil additive. Thirdly, biochar-supported phosphate (BP) effectively reduced Pb2+ mobility in simulated contaminated soil. Pb2+reacted with phosphate from Ca10(PO4)6(OH)2 embedded in the biochar supported phosphate at pHPb10(PO4)6(OH)2. Finally, the amendment of acidic soils with modified P-enriched modified-biochar improved soil buffering capacity because of its enhanced ash contents, alkalinity, and surface functional groups. Spectroscopic methods were used to analyze biochar, soil, and plant materials extracts. Several other analytical methods including BET and thermogravimetric analyses were used to characterized biochar. These findings suggest that the use of phosphorus enriched modified-Douglas fir biochar in agricultural soil is a feasible relatively low-cost, effective, and environmentally sustainable soil management and P recycling strategy

Cette étude vise à contribuer au développement d’un produit de construction à faible impact environnemental utilisant la terre crue. Pour cela, le comportement hygro-mécanique de la terre crue compressée à haute pression par une technique novatrice mise au point dans ce projet a été caractérisé. De plus, plusieurs méthodes de stabilisation ont été évaluées afin d’améliorer la durabilité de ce matériau, notamment vis-à-vis de l’érosion induite par l’eau. Une vaste campagne d’essais expérimentaux a été menée sur ces matériaux stabilisés ou non, à deux échelles différentes : les caractérisations des échantillons cylindriques (petite échelle) ont tout d’abord permis de sélectionner la formulation optimale. Par la suite, les tests menés à grande échelle sur les briques de terre compressée ont contribué à développer un produit pour la construction. Une nouvelle technique de fabrication basée sur l’application d’une contrainte de compactage très élevée (hyper-compactage) a été mise au point. Son objectif principal est d’augmenter la densité du matériau afin d’améliorer ses performances mécaniques. Les échantillons compactés par la méthode proposée présentent une densité sèche d’environ 2320 kg/m3, ce qui représente la valeur la plus élevée jamais enregistrée dans la littérature pour une terre non stabilisée. Les effets de la contrainte de compactage sur la microstructure du matériau ont été analysés par intrusion au mercure et adsorption d’azote liquide. Les résultats montrent que l’augmentation de la contrainte de compactage réduit la porosité du matériau, majoritairement les grands pores inter-agrégats. Cependant, le compactage mécanique influence peu les petits pores intra-agrégats. L'approfondissement de la caractérisation des propriétés microstructurales des échantillons stabilisés constitue un développement intéressant de ce travail. La résistance et la rigidité des échantillons non stabilisés et stabilisés ont été mesurées. Ces essais mécaniques confirment que la méthode d'hyper-compactage permet d’améliorer grandement la réponse mécanique du matériau par rapport aux techniques de fabrication existantes. Ainsi, les briques réalisées présentent une résistance en compression comparable à celle-là des matériaux traditionnels de construction (e.g. terre stabilisée et briques en terre cuite). Pour compléter cette étude, des essais mécaniques à l’échelle paroi sont à mener. Le comportement hygroscopique des échantillons stabilisés et non stabilisés a été analysé par la mesure du paramètre MBV (i.e. Moisture Buffering Value), qui traduit la capacité d’échange avec la vapeur d’eau. Il s'avère que la terre non stabilisée possède une excellente capacité à absorber et relarguer l’humidité ambiante. Cette capacité est, par contre, réduite pour les échantillons stabilisés testés dans le cadre de cette étude. La caractérisation du comportement thermique de la terre compressée à haute pression ainsi que l’analyse expérimentale des transferts thermo-hygroscopiques à l’échelle paroi représentent deux compléments d'étude afin de préciser le comportement hygroscopique d'un mur à base de terre crue. Enfin, la durabilité par rapport à l’érosion induite par l’eau des briques stabilisées et non stabilisées a été estimée à travers les essais d’immersion, de succion et de contact qui sont prévus par la norme DIN 18945 (2013). Les briques stabilisées montrent une meilleure résistance à l’eau par rapport aux briques non stabilisées. Toutefois, des études supplémentaires sont nécessaires pour améliorer les méthodes de stabilisation garantissant la durabilité dans le cas d'applications structurelles exposées aux intempéries, tout en maintenant de bonnes performances hygro-mécaniques et un faible impact environnemental. / The present work explores the hygro-mechanical behaviour of a raw earth material and investigates different stabilisation techniques to improve the durability of the material against water erosion. An extensive campaign of laboratory tests was performed on both unstabilised and stabilised materials at two different scales: small cylindrical samples and large bricks. An innovative manufacturing method based on the application of very high compaction pressures (hypercompaction) was proposed. Also, the compaction load was maintained constant for a sufficient period of time to allow soil consolidation. The main objective was to increase material density, thus improving mechanical performance. Samples compacted with the proposed method exhibited a dry density of about 2320 kg/m3, which is the highest value registered in the literature for an unstabilised earthen material. The effect of the compaction pressure on the material fabric was assessed by means of mercury intrusion porosimetry and nitrogen adsorption tests. Results showed that the increase of compaction pressure reduced material porosity with major effects on large inter-aggregate pores. On the contrary, small intra-aggregate pores were not affected by the mechanical compaction. Mechanical tests were then performed to measure stiffness and strength of both unstabilised and stabilised samples. These tests demonstrated that hypercompaction can largely improve the mechanical response of the material over conventional manufacturing methods. Hypercompacted bricks showed a compressive strength comparable with that of traditional building materials, such as stabilised compressed earth and fired bricks. The hygroscopic behaviour of both unstabilised and stabilised samples was investigated. The capacity of the samples to absorb/release water vapour was assessed by measuring their moisture buffering value (MBV). Results showed that unstabilised earth has an excellent capacity to buffer ambient humidity. This capacity was significantly reduced by the different stabilisation techniques tested in the present work. Finally, the durability against water erosion of both unstabilised and stabilised bricks was assessed by performing different tests prescribed by the norm DIN 18945 (2013). Stabilised bricks exhibited a higher resistance against water erosion compared to unstabilised bricks. Still, these materials cannot be adopted for structural applications exposed to natural weathering as indicated by the norm DIN 18945 (2013). Therefore, further investigation is required to identify novel stabilisation methods that can balance the needs of sustainability, durability, moisture buffering and mechanical performance.