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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Measurement and modelling of tillage and water erosion within intensive potato production systems of northwestern New Brunswick, Canada

Tiessen, Kevin January 2009 (has links)
No description available.
52

Fate and transport of herbicides used in growing transgenic canola in Quebec soils

Syan, Harvinder January 2013 (has links)
No description available.
53

Soil microbial community, soil aggregation and cropping system: study of their relationship

Caniquitte, Sabine Sophie January 2008 (has links)
No description available.
54

Assessing the effects of feedstock and pyrolysis temperature on biochar stability in soils

Hu, Yulin January 2015 (has links)
No description available.
55

Nitrogen fertilization and nutrition of canola in eastern Canada

Gurung, Bineeta January 2015 (has links)
No description available.
56

"A Well-Cared for Cow Produces More Milk"| The Biotechnics of (Dis)Assembling Cow Bodies in Wisconsin Dairy Worlds

Overstreet, Katy 16 February 2019 (has links)
<p> This dissertation examines intersections of care and production on commercial dairy farms in southern Wisconsin where farmers and their cows must produce ever more milk to keep farms in business. The maxim, &ldquo;a well-cared for cow produces more milk,&rdquo; is common sense in the dairy worlds of Wisconsin. It invokes the notion that putting time and money into caring for cows makes financial sense, but it obfuscates how optimizing cows toward milk production goals can instead create suffering. Amidst the moral knotting of this care-production logic expressed in a plethora of technical and scientific interventions into the dairy production system, humans and cows negotiate the everyday work of making milk. This thesis traces these forms of intervention and negotiation. </p><p> Farms, I argue, are patches, crosscut by multiple discourses that shape what it means to be a farmer and what it means to be a cow. Productivist discourse, which places pounds of milk at the heart of industry goals, justifies biotechnological interventions that seek to turn cows into machines of optimal milk and calf (re)production. These interventions target particular parts of cow bodies, as mechanistic components, in order to fine-tune them toward high milk production. </p><p> This dissertation performs a figurative (dis)assembly of human and bovine lives by unfolding the worlds and discourses that emerge through partitioning and tinkering with bodily parts: rumens, genes, ovaries, udders, and senses of taste. Through this unfolding, the multiple spatiotemporalities of production and the pursuit of efficiency become visible as material ways that cow bodies are optimized. A chapter on rumens demonstrates how cows are figured as cow-athletes that must have specialized diets, geared toward speeding up metabolism and thus the production of milk. A chapter on genes evokes the speculative futures where the imaginary Supercow and its yet unrealized production capacities await. A chapter on ovaries traces the hormonal manipulation of cow bodies toward synchronous reproduction and hides the toll of high-milk production. Taste, too, is partitioned, as a sensory capacity of the palate. A chapter on taste demonstrates how cows are made into subjects of nutritional discourse through caring practice that brings cow and human senses into recursive and mutual attunement. </p><p> By following the partitioning of cows, a key discursive move in the cow-as-machine paradigm, this dissertation follows how biotechnological interventions geared toward maximizing milk (re)production contribute to reimagining life and work on Wisconsin dairy farms in the midst of significant farm restructuring toward larger herds on fewer farms. This (dis)assembly, however violent, requires practices of care in order to hold cow bodies together as efficient producers. In following the discourses and practices that unfold around bodily (dis)assembly it is also possible to excavate the forms of resistance however small and the recuperative possibilities therein.</p><p>
57

Monitoring the spatial and temporal dynamics of the Brazilian Cerrado physiognomies with spectral vegetation indices: An assessment within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)

Ferreira, Laerte Guimaraes January 2001 (has links)
The large extension and diversity of the Cerrado vegetative cover, the second largest biome in South America, has a strong impact on regional, and possibly global, energy, water, and carbon balances. Nevertheless, as a major farming frontier in Brazil, it is estimated that about 40% of the Cerrado land cover has already been converted into cultivated pastures, field crops, urban development, and degraded areas. Despite this aggressive pace of land conversion, there have been few investigations on the operational utilization of remote sensing data to effectively monitor and understand this biome. Within this context, and within the goals and framework of the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), we evaluated the usefulness of spectral vegetation indices (VIs), to effectively monitor the Cerrado, detect land conversions, and discriminate and assess the conditions of the major structural types of Cerrado vegetation. Using a full hydrologic year (1995) of AVHRR, local-area-coverage (LAC), data over the Cerrado, converted to normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI), we were able to spatially discriminate three major communities based on their phenologic patterns. These included savanna formations and pasture sites, forested areas, and agricultural crops. We also analyzed wet and dry season, aircraft-based radiometric data and a ground-based set of biophysical measurements, collected over the Brasilia National Park (BNP), the largest LBA core site in the Cerrado biome. Overall, we found the MODIS vegetation indices, which include a continuity NDVI and the new enhanced vegetation index (EVI), to provide better performance capabilities with improved dynamic ranges and contrasts in seasonal dynamics. Land cover discrimination was favored by the NDVI, while the EVI more strongly responded to the seasonal contrast of the vegetative cover. Thus, the synergistic use of the MODIS VI products will very likely result in an improved monitoring capability and understanding of the Cerrado biome.
58

Evaluation of the feasibility for in situ bioremediation of mineral oil-contaminated soil

Chech, Andrea M. January 2003 (has links)
A greenhouse lysimeter experiment was performed to evaluate the use of in-situ bioremediation and phyto-remediation to reduce mineral oil concentrations in a weathered contaminated soil. The hypotheses for the study were (1) a combination of microbial- and phyto-remediation would yield a best remediation strategy, and (2) the addition of low levels (10 mg/L) of a biosurfactant would stimulate and increase the rate of remediation by increasing the bioavailability of the mineral oil in the soil. The results indicate, on average, a higher rate of mineral oil removal occurred in planted lysimeter tanks versus non-planted lysimeter tanks. Specifically, for unplanted treatments an average of 22% of the mineral oil was removed in 24 weeks in comparison to the planted treatments for which an average of 54% of the mineral oil was removed. The effect of application of fertilizer on mineral oil degradation was unclear, but a visual inspection showed that vegetated tanks receiving fertilizer had better growth. No conclusions can be made regarding the addition of biosurfactant. Though a couple of the lysimeter tanks receiving biosurfactant performed relatively well, overall, the results were inconclusive. Enumeration of mineral oil degraders showed that there was a statistical difference between planted tanks and unplanted tanks with planted tanks having higher numbers. These results help support the conclusion that plants enhanced mineral oil degradation. Enumeration of total heterotrophs showed that there was no statistical significant difference between the planted and unplanted treatments. In conclusion, this study demonstrated that a low-cost, low-maintenance approach to facilitate remediation of weathered mineral oil contaminated soil is a combination of microbial- and phyto-remediation.
59

Soil, groundwater, and alfalfa yield response to manure and compost applications in an arid environment

Tanksley, Koli January 2003 (has links)
The assessment of environmental degradation from farming practices has received recent attention due to the concern for sustainable agriculture. The United States Department of Agriculture and the Environmental Protection Agency have set forth the Unified National Animal Feeding Operation Strategy to protect the nation's water resources from contamination. The Unified Animal Feeding Operation Strategy requires that field application of manure, a common fertilization method and manure disposal practice, may not exceed crop nutrient needs. This requirement necessitates studies to determine how the multiple variables involved interact so that farmers may comply with the regulation. In this research, the effects of the application of manure, both fresh and composted, on a production alfalfa (Medicago sativa L.) field was examined. Manure and compost were applied to a production alfalfa field to determine the impact on alfalfa yield, soil nutrient content, and the potential for nitrate leaching. A conventional "no nitrogen added" treatment was also maintained as a control. Manure and compost were applied after each harvest in amounts such that the amount of nitrogen removed in the alfalfa harvest was replaced with the same amount of nitrogen in manure or compost. Application rates varied from 35 to 476 kg nitrogen ha⁻¹ after each harvest. It was found that the finer particles of the compost incorporated into the soil profile better than the chunky form of the manure. Soil analysis down to 150 cm depth showed that the compost treatment plots contained nearly 3000 kg total nitrogen ha⁻¹, the manure plots contained about 1750 kg ha⁻¹, and the no nitrogen plots had approximately 1400 kg ha⁻¹. Final PO₄-P soil analysis revealed that compost plots contained about 125 kg PO₄-P ha⁻¹, manure plots had approximately 115 kg ha⁻¹, and no nitrogen plots had only 20 kg ha⁻¹. Alfalfa yield did not vary between treatments throughout the one and a half year study. Also, no detectable nitrate or phosphate was found in the leachate collected from each of the treatments.
60

Electrokinetic management of nitrate movement in drip irrigated soils

Jia, Xinhua January 2004 (has links)
Nitrate contamination of surface and groundwater has become a serious concern in many agricultural areas throughout the world. The major source of nitrate contamination is believed to be nitrogen fertilizer from agricultural fields. Best Management Practices have been developed to guide fertilizer use and minimize nitrogen losses, but do not address control of nitrate movement from the crop root zone. It is proposed that an in-situ method, electrokinetics (EK), could be used to control nitrate movement, retaining it near the root zone. Lysimeter experiments were conducted to evaluate the effect of parallel electrodes on pH and nitrate distribution in field soils subjected to an electrical input. However, the expected results, increased nitrate retention, reduced sodium and calcium concentration and lower pH values near the anode, were not attained consistently in the test soils with and without Sudan grass. Small scale experiments in a vertical, partially saturated sandy soil column (25 cm height by 14 cm diameter) were conducted to evaluate the optimal EK parameters. After 80 mA current for 6 h the nitrate was retained near the anode, with the highest measured nitrate concentration of 7155 mg/L within 5 mm of the anode. The nitrate concentration at the cathode was 1/5 of the inflow solute concentration (221 mg/L). The pH was 11 near the cathode, 3.5 near the anode, and showed little changes in intermediate layers. The results demonstrate that in sandy soils nitrate can be strongly retained near the anode, even against gravity effect. As the percentage of illite clay in the soil increased, the EK effect decreased; due to the increase of fine clay particles both the transports of ions and the water were inhibited. The loam soil showed some increase in the nitrate concentration near the anode, but the clay soil showed no change. An increase of pH near the cathode was seen in all soils. The electrical potential analysis showed the sandy soil required the highest electrical potential 97.23 V, loam soil was 18.24 V and clay soil was 14.22 V.

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