Thesis (M.S.)--Virginia Polytechnic Institute, 1951. / Vita. Includes bibliographical references (leaves 50-53). Also available via the Internet.

L’ancienne fonderie de plomb Metaleurop Nord a rejeté énormément de métaux dans l’environnement qui est très dégradé du fait de cette contamination et de la fragmentation des paysages. L’objectif principal du travail de thèse a été de s’interroger sur quel est/sont le(s) meilleur(s) aménagement(s) pour favoriser une reconnexion et une restauration d’une fonctionnalité des sols les plus contaminés sur le secteur ? Trois expérimentations ont été menées sur le terrain. La première dresse un état de la fonctionnalité de sols de parcelles anciennement boisées à travers la comparaison d’un panel de 55 indicateurs physico-chimiques et biologiques Les deux autres s’intéressent à l’influence d’un aménagement, l’une en étudiant l’influence de la composition pariétale des essences et la pollution métallique des litières, l’autre tournée d’avantage sur le processus de dégradation de la litière. L’étude de la recolonisation des milieux dégradés, à l’aide de la technique du mulching, a été réalisée à travers la mise en place d’une expérimentation sur le terrain qui a été suivie 2 ans. Les principales conclusions de ce travail en terme de préconisations sont de favoriser les plantations mixtes et les essences locales, prendre en compte les types de sol (teneurs en CaCO3, hydromorphie, concentrations en métaux…) et les exigences écologiques des essences envisagées, amender les sols avec des amendements minéraux ou organo-minéraux afin de limiter la mobilité des métaux, varier les densités de plantation afin de favoriser un maximum d’espèces, développer des zones de transition entre les milieux et accélérer le processus de colonisation via la technique du mulching.h / The former lead smelter Metaleurop Nord has rejected a lot of metals to environment which is immensely degraded due to this contamination and fragmentation of landscapes. The main aim of this thesis was to ask what is / are the best layout (s) to promote a reconnection and restoration of a feature of the contaminated agricultural soils of the site "Metaleurop"? Three experiments were conducted in the field. The first gave the state of the functionality of floor formerly woodlots plots and three references (a wood, a hedge and an agricultural system) through comparison of a panel of 55 physico-chemical and biological Indicators. Two others were interested in the influence of management; one in studying the influence of the parietal species composition and metal pollution, another tour more about the litter degradation process was realized with the litterbags technique. The study of the recolonization of degraded environments, using a simple landscaping technique (mulching), was achieved through the establishment of a field experiment which was followed for two consecutive years. Main conclusions of this work in terms of recommendations are: promoting mixed plantations and local species, taking into account soil types (levels of CaCO3, waterlogging, metal concentrations ...) and ecological requirements of the proposed species, amending soils with mineral or organo-mineral amendments to limit the mobility of metals, varying planting densities to promote maximum species, developing transition zones between environments and accelerating the process of colonization through the technical mulching.

The effects of a straw mulch, applied either uniformly or in strips, on the surface energy balance and soil thermal regimes are investigated using a numerical solution to the two-dimensional soil heat transfer equation. The numerical technique used is an extended version of Barakat and Clark's (1966) alternating direction explicit method. The modified technique can solve problems that are periodic in time and/or space, on either rectangular domains or domains with a curvilinear upper boundary, and in which the soil thermal properties may vary with position, time, or temperature. The method also incorporates non-uniform grid spacings to reduce computation time and to increase efficiency. The straw mulch is represented as a single layer of constant shortwave and longwave transmissivities and reflectivities. Vertical transport of heat and water vapour through the mulch is evaluated by bulk transfer equations. Shading of the bare strip and reflection of radiation onto it by the sides of the mulch strip, as well as the reduction of the sky-view factor seen by the bare strip, are included. Solar irradiance, air temperature and water vapour density, wind speed, soil thermal properties and mulch parameters are the required inputs. Evaporation is estimated using a surface resistance model to vapour flow. The model is compared with micrometeorological measurements made in soils covered with barley straw, either uniformly at rates of 2, 10 or 20 t/ha or in 0.30 m wide mulch strips (10 t/ha rate) alternating with 0.10 m wide bare strips, with the strips oriented in north-south, northeast-southwest, or east-west directions. The results show that for the uniformly applied mulch soil temperatures can be adequately predicted but evaporation is underestimated. Both soil temperatures and evaporation are underestimated in the bare strip. The differences are attributed to the penetration of wind eddies into the straw mulch and the microscale advection from the warm straw strips onto the relatively cold bare strips. / Land and Food Systems, Faculty of / Graduate

Call number: LD2668 .T4 1967 J65 / Master of Science

A series of tests was performed in winter 1996 to measure degradation of paper mulches with the help of physical and mechanical properties. Four types of paper used for mulching, kraft paper gauge 40, 60 and 80 and waxed paper were laid over soil in two growth chambers. They were kept under observation for 27 days under controlled temperature, humidity and light. Mulches were sprayed with water to simulate rain. Tensile and puncture tests were performed on each type of paper every day. Four mechanical properties; stress, strain, energy and tensile energy absorption were calculated from the force-deformation curve obtained by tensile test. Two mechanical properties; displacement and force to break were calculated from the force-deformation curve obtained by puncture test. A special die had to be designed to perform puncture tests. This design eliminated shear loading which otherwise would have been present in normal puncture tests. / Results showed that paper - 3 (kraft paper gauge - 80) was best suited for mulching as the mechanical properties were stable through 27 days with negligible fluctuations. Waxed paper required less force to break but was stable through 27 days of experimentation. / A three-way factorial model was developed to analyze the results statistically. A SAS program was written to model the results. The fitted model was in very good agreement with the actual values.

No description available.

Thesis (M. S.)--Michigan State University, Dept. of Crop and Soil Science, 2006. / Title from PDF t.p. (viewed on November 12, 2007). Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (leaves 88-93).

Thesis (M.F.)--Oregon State University, 1962. / Typescript. Includes bibliographical references (leaves 66-68). Also available on the World Wide Web.

Thesis (M.S.) in Plant, Soil and Environmental Sciences--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 112-118).

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains x, 83 p.; also includes graphics (some col.). Includes bibliographical references (p. 77-83). Available online via OhioLINK's ETD Center