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Nitrogen Transfer From Cover Crops To The Subsequent Grain Crop And The Influence Of Variability In Winter Conditions, Spencer Heuchan
Nitrogen Transfer From Cover Crops To The Subsequent Grain Crop And The Influence Of Variability In Winter Conditions, Spencer Heuchan
Electronic Thesis and Dissertation Repository
Cover crops, which are used to provide ground cover after the harvest of the grain crop, can potentially improve the sustainability of agroecosystems by reducing nutrient losses. However, few data are available to document the extent to which cover crops improve both the retention of soil nitrogen (N) and the transfer of this N to the grain crop. The efficiency of this N transfer may be further influenced by variation in winter soil temperature; for example, reduced snow cover can increase the frequency and intensity of soil freezing, which can affect the survival of cover crops and the timing of …
Investigating Mycelial-Crop Residue Mat Application To Reduce Early-Colonizing Weeds In Row-Crop Agriculture, Donald T. Watson
Investigating Mycelial-Crop Residue Mat Application To Reduce Early-Colonizing Weeds In Row-Crop Agriculture, Donald T. Watson
Electronic Thesis and Dissertation Repository
Herbicide use within conventional agriculture has contributed to greatly increased crop yields since its widespread adoption, but environmental concerns regarding overuse and reliance on selective herbicides continue to mount. Using five fungal species and two crop residues in a factorial design, I created a novel slurry to control weeds through inhibition by the mycelial mat formed after application to soil. I monitored weed stem counts and the strength of the mycelial mat under the treatments. Additionally, as a proxy for crop yield, I measured the wet and dry mass of crop plant grown under application treatments. Weed prevalence was significantly …
Rnai Targeting Of Manduca Sexta Using Chloroplast-Encoded Long Dsrna, William Burke
Rnai Targeting Of Manduca Sexta Using Chloroplast-Encoded Long Dsrna, William Burke
Electronic Thesis and Dissertation Repository
Pest management strategies are crucial for reducing insect crop damage, and methods with species-specific effect are particularly desirable. Expressing dsRNA with sequence complementarity to a vital gene of feeding pests is a strategy that has shown potential. I modified the chloroplast genome of cultivated tobacco, Nicotiana tabacum, by adding a sequence encoding a 2222 base pair dsRNA complementary to the vacuolar-type H+-ATPase subunit A mRNA of Manduca sexta and demonstrated expression of the product in leaves of the plants. Although feeding this same dsRNA that was synthesized in vitro to larvae knocked down expression of the target …
Investigating The Suitability Of The Crayfish Metabolome As A Bioindicator Of Stream Conditions, Natalie M. Izral
Investigating The Suitability Of The Crayfish Metabolome As A Bioindicator Of Stream Conditions, Natalie M. Izral
Electronic Thesis and Dissertation Repository
The suitability of the crayfish metabolome as a bioindicator of stream conditions was investigated because there is a need for fast responding, sensitive, diagnostic, and ecologically relevant bioindicators. A laboratory study assessed Procambarus clarkii metabolome sensitivity to six different treatments of food or DO stress. A field study in subcatchments of the Red River Valley, Manitoba, Canada assessed the effects of land-use type (reference, agriculture, wastewater effluent) on the Orconectes virilis metabolome. Crayfish were sacrificed, and hepatopancreas, gill, and tail tissues were dissected. Analyses found the metabolome was sensitive enough to potentially diagnose food and DO stress in P. clarkii …
Response Of Soil Nitrification To The Veterinary Pharmaceuticals Monensin, Ivermectin And Zinc Bacitracin, Magda A. Konopka
Response Of Soil Nitrification To The Veterinary Pharmaceuticals Monensin, Ivermectin And Zinc Bacitracin, Magda A. Konopka
Electronic Thesis and Dissertation Repository
Pharmaceutical residues can reach agricultural land through amendment with animal or human waste. Since 2010, a series of replicated plots received annual applications of ivermectin, monensin and zinc bacitracin, either singly or in a mixture, at 0.1 mg/kg and 10 mg/kg concentrations. I collected soil samples before and after the fourth annual application of pharmaceuticals and assayed them for functional changes and amoA gene abundance, a gene needed for ammonia oxidation. In 2013, I exposed the soils to 100 mg/kg in a laboratory experiment which resulted in acceleration of nitrification. Under 10 mg/kg treatments in the field the abundance of …
Extent, Characteristics And Downstream Effects Of Stream Enclosure In Southwestern Ontario, Katie L. Stammler
Extent, Characteristics And Downstream Effects Of Stream Enclosure In Southwestern Ontario, Katie L. Stammler
Electronic Thesis and Dissertation Repository
In a 16000 km2 area of southwestern Ontario, almost 15% of all streams have been enclosed (buried) largely for agricultural purposes. ArcGIS was used to characterize the natural features of catchments and to calculate enclosedness (proportion of stream network enclosed; x̅ = 16.5%, n = 10106). Catchments with the highest enclosedness received >990 mm of precipitation annually and had high drainage density (>1.9 km/km2), while catchments with the lowest enclosedness receivedannually, were characterized by clay and undrumlinized till plains and had relatively shallow water tables (m). These natural features influence where enclosure is likely to occur, …