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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.
91

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

Tiessen, Kevin January 2009 (has links)
In Canada, there is growing acceptance that tillage erosion is a serious form of soil degradation and a threat to the sustainability of agriculture across the country. To date, the potential for tillage erosion within potato (Solanum tuberosum L.) production systems has not been investigated. To address this issue, field experiments were conducted in northwestern New Brunswick to generate tillage translocation and erosivity values for primary, secondary and "tertiary" (i.e., field operations conducted during planting, hilling and harvesting) tillage implements commonly used for potato production. The potential for tillage erosion was equally high for the mouldboard plough, chisel plough and offset disc, and larger than that for the vibrashank. Surprisingly, tertiary field operations moved soil further and were more erosive than primary and secondary tillage operations, alone or combined. Overall, the risk of tillage erosion during the production of potatoes is considerably greater than that for other major cropping systems in Canada. Water erosion is also a serious problem within the potato producing regions of Atlantic Canada. However, to date, no previous studies have looked at the impact of both tillage and water erosion on total soil erosion within potato production. Using repeated-measurements of the fallout radionuclide cesium-137 (137Cs), annual soil losses between 1990 and 2005 at a New Brunswick benchmark site were 13.6 Mg ha-1 yr-1, with approximately half of the mapped field having soil losses greater than the tolerable soil loss limit of 6 Mg ha-1 yr-1. A new Directional Tillage Erosion Model (DirTillEM) was used to account for the apparent effect of tillage direction and field boundaries on soil redistribution at this field site. Overall, DirTillEM predictions improved relationships between 137Cs redistribution and estimated soil erosion over those determined by two previously published wate / Au Canada, il est maintenant admis que l'érosion par le travail du sol est une forme importante de dégradation du sol et une menace à la viabilité de l'agriculture dans tout le pays. Jusqu'à présent, le potentiel de l'érosion par le travail du sol dans la culture de la pomme-de-terre (Solanum tuberosum L.) n'a pas été étudié. A cette fin, des expériences au champ ont été menées dans le nord-ouest du Nouveau-Brunswick afin de produire des valeurs pour la translocation du sol ainsi que pour l'érosivité des équipements utilisés au cours des travaux du sol primaire, secondaire et "tertiaire" (c.-à-d., les opérations de plantation, buttage et de récolte) pour la culture de la pomme-de-terre. Le potentiel de l'érosion par le travail du sol était semblablement élevé pour la charrue à versoirs, le chisel et le pulvériseur offset, mais moins élevé pour le vibroculteur. Etonnamment, les opérations tertiaires ont déplacé le sol plus loin et étaient plus érosives que les opérations primaire ou secondaire, seules ou combinées. Dans l'ensemble, le risque de l'érosion par le travail du sol dans la culture de la pomme-de-terre est considérablement plus important que pour les autres systèmes culturaux typiques du Canada. L'érosion par l'eau est également un problème d'envergure dans les régions de production de la pomme-de-terre du Canada atlantique. Cependant, aucune étude antérieure ne s'est penchée sur l'impact combiné de l'érosion par le travail du sol et par l'eau dans cette culture. Des mesures répétées des retombées radioactives de césium-137 (137Cs) ont révélé des pertes de sol annuelles de 13.6 Mg ha-1 an-1 entre 1990 et 2005 à un site de référence au Nouveau-Brunswick, avec environ la moitié des endroits échantillonnés ayant des pertes au delà du seuil tolérable de 6 Mg ha-1 an-1. Un nouveau modèle, le Directional Tillage Erosion Model (DirTillEM
92

Aboveground nitrogen accumulation as a function of time in corn and winter wheat

Holtz, Starr LaChelle, January 2007 (has links) (PDF)
Thesis (M.S)--Oklahoma State University, 2007. / Vita. Includes bibliographical references.
93

In situ characterization of soil properties using visible near-infrared diffuse reflectance spectroscopy

Waiser, Travis Heath, January 1900 (has links)
Thesis (M. S.)--Texas A&M University, 2006. / "Major Subject: Soil Science" Title from author supplied metadata (automated record created on Nov. 2, 2007.) Vita. Abstract. Includes bibliographical references.
94

Sulfur dynamics and activities of sulfur-transforming enzymes in prairie soils under different management practices

Shawaqfeh, Samar S., January 2008 (has links) (PDF)
Thesis (M.S.)--Oklahoma State University, 2008. / Vita. Includes bibliographical references.
95

Impact of mineralogy on potassium dynamics and retention behavior in Bangladesh soils used in rice cropping systems

Biswas, Sumitra Bose, January 1900 (has links)
Thesis (M. S.)--Texas A&M University, 2008. / "Major Subject: Soil Science" Title from author supplied metadata (automated record created on Oct. 13, 2008.) Vita. Abstract. Includes bibliographical references.
96

Field evaluation of transgenic peanut lines for resistance to Sclerotinia blight and yield

Douglas, Trevorne Nicholas, January 2004 (has links) (PDF)
Thesis (M. S.)--Oklahoma State University, 2004. / Vita. Includes bibliographical references (p.60).
97

Identification of optical spectral signatures for detecting cheat and ryegrass in winter wheat, and determination of optimum rate and growth stage of foliar applied phosphorus in corn

Desta, Kefyalew Girma, January 2004 (has links) (PDF)
Thesis (Ph. D.)--Oklahoma State University, 2004. / Vita. Includes bibliographical references.
98

Spatial association between the locations of roots and water flow paths in highly structured soil

Gardiner, Nathan T. , 1977- January 1900 (has links)
Thesis (M. S.)--Texas A&M University, 2003. / "Major Subject: Soil Science" Title from author supplied metadata (automated record created on Feb. 17, 2005.) Vita. Abstract. Includes bibliographical references.
99

Identifying soils with potential of expanding sulfate mineral formation using electromagnetic induction

Fox, Miranda Lynn, January 1900 (has links)
Thesis (M.A.)--Texas A & M University, 2004. / "Major Subject: Soil Science." Title from author supplied metadata (automated record created on Oct. 15, 2004.). Vita. Abstract. Includes bibliographical references.
100

Phosphorus reduction in dairy effluent through flocculation and precipitation

Bragg, Amanda Leann, 1980- January 1900 (has links)
Thesis (M. S.)--Texas A&M University, 2003. / "Major Subject: Soil Science" Title from author supplied metadata (automated record created on Feb. 17, 2005.) Vita. Abstract. Includes bibliographical references.

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