The objective of this study was to determine if the presence of two ALS inhibiting herbicide residues in three Saskatchewan soils would result in an additive, synergistic, or antagonistic interaction. This was determined through field trials where herbicides were applied sequentially over the course of two years and through dose-response modelling. The herbicides examined in these experiments were imazamethabenz, flucarbazone-sodium, sulfosulfuron, and florasulam, each in combination with imazamox/imazethapyr. The phytotoxicity and persistence of the herbicides in soil was assessed using an Oriental mustard root inhibition bioassay. The determination of herbicide interaction was made through the comparison of the experimentally observed values to theoretically expected values derived from a mathematical equation.<p>The dose response curves created by placing incremental concentrations of these herbicides in soil were compared using the I50 parameter, which is the concentration resulting in a 50% reduction in root length. It appeared that soil organic matter followed by soil pH had the greatest effect in reducing herbicide residue phytotoxicity in the tested soils. Based on the bioassay analysis of sequentially applied ALS inhibiting herbicides, it is proposed that the phytotoxic effect of herbicide residues in soil result in additive injury effects rather than synergistic or antagonistic interactions.

The dynamic properties of soil are normally inferred from laboratory tests on collected samples or from empirical relations. The soil properties measured in the field can be very different from those predicted from laboratory tests. It is very difficult to determine directly in the field the variation of the shear modulus and damping with the level of excitation (level of strains). This remains today a major gap in our knowledge and our ability to conduct reliable seismic analyses. The main objective of this study is to assess the feasibility of determining reliably in situ the shear modulus and damping of the soil as functions of the level of strains, developing a method to compute these properties from the measured data and providing practical recommendations for the use of the procedure. To achieve this objective, extensive and comprehensive sets of experimental and analytical studies were conducted in parallel. Some numerical analyses were performed to provide a better understanding for performing in situ tests with the newly developed vibroseis loading systems. In addition, the dynamic response of a surface foundation in vertical vibration were studied. This dissertation mostly focuses on the numerical aspects of the problem while some experimental data are also studied and utilized. Field tests were conducted to estimate shear moduli of silty sands at two sites, the Capital Aggregate Quarry and the Texas A&M University sites. Estimated nonlinear shear moduli presented very consistent trends regardless of the analysis methods and test sites. They showed larger elastic threshold shear strains, 1.5 × 10−3 % for the Capital Aggregate Quarry site and 2 × 10−3 % for the Texas A&M University site, than the mean of shear modulus curve for cohesionless soils proposed by Seed and Idriss (1970). Estimated moduli closely followed the mean of Seed and Idriss (1970) at strains larger than 6 × 10−3 % for both sites. Internal damping ratio can also be estimated if additional data are gathered from in situ tests in the future.

<p>The focus of this study is on potential problems resulting from construction on expansive soils in Kibaha region, Tanzania. For the fact that most of the affected structures are founded on expansive soils, a clear understanding of the soil behaviour and their interaction with structures, specifically as they relate to shallow foundations, has been of more interest to the study in order to evaluate properly the source of the problem.</p><p>The geotechnical behaviour of expansive clay soils is investigated by looking into the geomorphologic, geological and climatic conditions and mineralogical composition of the soils in the study area. The geotechnical results are linked with the performance of the foundation as well as structures.</p><p>Two sites, representative of known problem-areas in Kibaha were selected for geotechnical tests. Geotechnical site investigation consisted of open trial pits, profile description and the collection of both disturbed and undisturbed samples.</p><p>The collected samples were submitted to soil laboratories at KTH and DIT for mineralogical composition tests, natural water content, density, Atterberg limits and swell tests (free swell and swelling pressure). The results of this investigation indicate that soil in Kibaha contains clay (31%), have high liquid limit (59%) and plastic limit (37%) which indicate high potential swell.</p><p>Since swell potential and swell pressure are key properties of expansive soils, the swell parameters were measured by free swell tests and one-dimensional oedometer swell tests respectively. The free swell ranged from 100% to 150% and the swell pressure was in the region of 45 kPa.</p><p>The properties of expansive soils were confirmed by the x-ray diffraction test which showed the presence of montmorillonite in the soil. It is from this fact that the source of the problem is in the expansive soils coupled with poor building materials.</p><p>Physical conditions of the surveyed properties in the area confirmed the hypothesis of building damages due to poor building materials triggered by expansive soils. In support of the obtained data, the actual behaviour of the foundations is supplemented with prototypes of strip foundations whose performances are to be monitored over a long period. Finally, suggested are the ways forward to solve the problem of foundation on expansive soil.</p>

Detailed soil and water data are essential to ensure the optimum long-term management of fields. The objective of this study was to estimate water table depths, spatially variable and layered soil properties using electromagnetic induction methods. Soil samples were collected and analyzed within two wild blueberry, a soybean-barley and a pasture fields. Observation wells were installed. The DualEM-2 was calibrated to predict the soil properties and groundwater depths. The apparent ground conductivity (ECa) and water table depths were measured simultaneously from each well, before and after every significant rainfall for three consecutive days. Comprehensive surveys were conducted in selected fields to measure ECa with DualEM-2. Survey data were imported in C++ program to estimate layered soil properties using mathematical models. Regression models were developed to predict soil properties and groundwater depths. The predicted soil properties and groundwater table maps were generated. This information can help to develop variable rate technologies.

No description available.

A field experiment initiated in spring 2012 was established to assess the relationships between grain yield, grain protein and soil properties including elevation, electrical conductivity, pH, and organic carbon in an undulating landscape. Grain protein can reflect the balance of nitrogen (N) relative to other yield limiting factors. The objective of this study was to 1) assess relationships between soil properties, crop yield and protein content in an undulating landscape in south-central Saskatchewan, and 2) determine feasibility of using protein content along with yield and soil data in identifying variable rate N application zones. In 2012, wheat, canola and peas were seeded. Soil samples and harvest measurements were taken from two transects in each field area. Wheat, canola and pea yields ranged from 882 to 2554, 1143 to 2342, and 839 to 3122 kg ha-1 respectively, while protein content for wheat, canola and peas ranged from 10.5 to 14.4, 14.2 to 20.6 and 14.5 to 17.7 percent respectively. Protein in wheat was positively correlated with pH in the 30-60 cm depth and negatively correlated with electrical conductivity in the 30-60 cm depth. Protein in canola was positively correlated with organic carbon in the 0-30 cm depth. Wheat yield was positively correlated with organic carbon in the 0-30 cm depth. Pea yield was negatively correlated with electrical conductivity in the 0-30 and 30-60 cm depths. In spring 2013, wheat was seeded on canola and pea stubble and canola seeded on wheat stubble with varied N rates on one side of each transect with a constant N rate on the other. Greater mean yields were observed from the varied N rate versus the control in the canola-wheat (3163 vs 2256 kg ha-1) and wheat-pea (4716 vs 4155 kg ha-1) rotations. A negative yield from the varied N rate versus the control was observed in the wheat-canola (2216 vs 3012 kg ha-1) rotation. However, these yield differences were not significant at p < 0.05.

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第22101号 / 地環博第187号 / 新制||地環||37(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 舟川 晋也, 教授 西前 出, 准教授 真常 仁志 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

The problems with microplastics, small plastic particles contaminating the environment, is a subject of heated discussions today. It has been recognized that the microplastics are not inert, but instead they have an impact on all enviromnental compartments. There are studies describing the negative effects of microplastics, for example on fauna and flora or on human health, but the effects on soil quality have not been sufficiently described. The aim of this thesis was to assess the short and medium term effects that microplastics could have on the soil. In this work, a series of experiments were performed to elucidate the fate of microplastics in the soil. Changes in soil organic matter thermal properties, soil respiration, amount of water and soil aggregation depending on the incubation time were monitored. Three types of agricultural land (chernozem, cambisol and phaeozem), which were contaminated with different concentrations od PET and tyre rubber, were tested. The results confirmed the specific effects of microplastics on soil properties, which were observed in non-incubated samples (i.e. at the time of incubation 0 months), microplastics did not behave inertly in the soil and affected, for example, soil properties, texture and respiration.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20443号 / 農博第2228号 / 新制||農||1050(附属図書館) / 学位論文||H29||N5064(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 神﨑 護, 教授 北島 薫, 教授 大澤 晃 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM