Drury C.F.,Agriculture and Agri Food Canada |
Reynolds W.D.,Agriculture and Agri Food Canada |
Parkin G.W.,University of Guelph |
Lauzon J.D.,University of Guelph |
And 9 more authors.
Canadian Journal of Soil Science | Year: 2016
Nitrogen (N) leaching from soil into surface and ground waters is a concern in humid areas of Canada. As a result, N management protocols, including the Ontario N Index, are widely used to identify N leaching risk, although field assessment remains limited. Nitrogen fertilizer and chloride (Cl) tracer were fall-applied to five agricultural soils in Ontario with different textures and hydrologic soil groups (HSG) to assess the Ontario N Index and characterize inorganic N movement over 1 yr. The treatments included three N rates (0, 100, and 200 kg N ha−1) plus Cl tracer and 200 kg N ha−1rate without Cl. After spring thaw, N loss from the crop root zone (top 60 cm) ranged from 68% for Brookston clay loam to 99% for Harrow sandy loam. A strong linear relationship between apparent N recovery and apparent Cl recovery indicated that N loss from the root zone occurred primarily by downward leaching. Leaching was controlled by the minimum measured saturated hydraulic conductivity (Ksat), and good estimates of N leaching were obtained using a quasi-theoretical relationship between N loss and Ksat.We concluded that Ontario N Index estimates of N leaching risk might be improved by including site-specific measurements of Ksat. © 2016, Agricultural Institute of Canada. All rights reserved. Source
Nadler A.J.,Manitoba Agriculture |
Bullock P.R.,University of Manitoba
Climatic Change | Year: 2011
Long-term (approximately 80 years) daily climate records at 12 weather stations across the agricultural production region of the Canadian Prairies were assessed to evaluate trends in seasonal heat units and moisture characteristics for corn (Zea mays). Crop water demand (CWD) and crop water deficit were modelled at each station. Growing season accumulation of these as well as corn heat units (CHU) and rainfall were tested for long-term trends using linear regression. Significant positive trends in CHU were present in the southernmost stations while the northern stations displayed no trend or significant negative trends. Growing season precipitation showed a significant increase on average and most stations showed a positive trend but only one station showed a significant positive trend. CWD declined at most stations with significant negative trends at seven stations. Crop water deficient also declined with significant negative trends at six stations. The spatial variation in these results and those reported in other studies in the region underscores the difficulty involved in forecasting future trends in agroclimatic conditions. © 2010 Springer Science+Business Media B.V. Source
Dosdall L.M.,University of Alberta |
Carcamo H.,Agriculture and Agri Food Canada |
Olfert O.,Agriculture and Agri Food Canada |
Meers S.,Crop Diversification Center South |
And 2 more authors.
Biological Invasions | Year: 2011
Agroecosystems in the western Canadian provinces of Alberta, Saskatchewan, and Manitoba have been invaded by several alien herbivorous insects from several orders and families. These species have caused very substantial reductions in yield and quality of the dominant crops grown in this region, including cereals (primarily wheat, Triticum aestivum L., barley, Hordeum vulgare L., and oats Avena sativa L.), oilseeds (primarily canola, Brassica napus L. and Brassica rapa L., and mustard, Sinapis alba L. and Brassica juncea (L.) Czern.), and pulses (primarily field pea, Pisum sativum L., lentil, Lens culinaris Medik., and chickpea, Cicer arietinum L.). In this study, we used literature searches to identify the major species of insect pests of field crops in western Canada and determine those species indigenous to the region versus species that have invaded from other continents. We summarize invasion patterns of the alien species, and some estimated economic costs of the invasions. We document the invasion and dispersal patterns of the cereal leaf beetle, Oulema melanopus L. (Coleoptera: Chrysomelidae), for the first time in all three provinces. We also report the co-occurrence of its exotic parasitoid, Tetrastichus julis (Walker) (Hymenoptera: Eulophidae), and implications for classical biological control. We present results of field studies describing the dispersal patterns of a second recent invader, the pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae). The implications of invasions in this region are discussed in terms of economic and ecological effects, and challenges posed for pest mitigation. © 2011 Springer Science+Business Media B.V. Source
Brady J.,University of Manitoba |
Hernandez-Doria J.D.,University of Manitoba |
Bennett C.,Manitoba Agriculture |
Guenter W.,University of Manitoba |
And 2 more authors.
Avian Pathology | Year: 2010
The present study determined the effect of Clostridium perfringens isolates taken from necrotic enteritis (NE) outbreaks on organic farms in a NE virulence testing model. Thirteen strains were isolated in the course of the study. Six C. perfringens field isolates were taken from a naturally occurring NE outbreak on an organic farm. Polymerase chain reaction toxinotyping was used to establish C. perfringens strains, as well as to create a toxin profile. All field isolates were found to be type A and positive for alpha, beta-2 and netB toxin genes. During the NE virulence model, digesta samples were collected before oral inoculation to define the C. perfringens found as part of the natural flora. Three of the five natural flora isolates were found to be C. perfringens type E while the other two isolates were type A; only four of five isolates were positive for either netB or beta-2 toxin genes. Two isolates collected after inoculation were C. perfringens type A positive for cpb2 and netB. All isolates were tested positive for the quorum-sensing-related gene luxS, regardless of the strain source. The presence of luxS, alpha, netB and beta-2 toxin genes seems not to be a determinant of the disease as they were present in isolates from both outbreak birds as well as healthy and pre inoculated birds. The C. perfringens field isolates induced mild NE lesions in one-half of the birds during the challenge study. Other mechanisms must play a role in the development of the disease beyond toxinotype, potentially including intestinal ecology and health, which would account for acute disease as seen in the field outbreak. © 2010 Houghton Trust Ltd. Source
Carruthers C.,University of Saskatchewan |
Gabrush T.,University of Saskatchewan |
Schwean-Lardner K.,University of Saskatchewan |
Knezacek T.D.,University of Saskatchewan |
And 2 more authors.
Journal of Applied Poultry Research | Year: 2012
Commercial laying hens in North America are typically beak trimmed to prevent injury and mortality caused by feather pecking and cannibalism. Beak trimming is most commonly performed on day-old chicks at the hatchery, either by hot blade (HB) or infrared (INF) techniques. The differences between these 2 methods and the potential variability within each method may cause morphological differences in the beaks of laying hens throughout their production cycle. Few data are available detailing variations between the beaks of laying hens after trimming in commercial settings. The purpose of this field survey was to measure beak lengths of 4 commercial laying hen flocks at 2 age ranges treated by either HB or INF techniques at hatch. Statistical analyses of the data for the 2 treatment types were not possible because of genetic and environmental differences between flocks; therefore, statements comparing treatments are not meant as definitive and are provided for general information only. Infrared-treated hens had shorter beaks with a lower SEM, and they generally exhibited fewer beak abnormalities than HB-trimmed hens at both ages. It is our observation in this field survey that INF-treated commercial hens seemed to have less variation in beak length and fewer beak abnormalities. ©2012 Poultry Science Association, Inc. Source