Examining Tillage and Crop Rotation Effects on Weed Populations in the Canadian Prairies
The Canadian Prairies occur at the northern portion of the Great Plains of North America (see Figure 8.1). This large area of 35 million ha of cropped land has been subdivided into eight ecoregions (Ecological Stratification Working Group, 1995) that are areas of similar landforms, climate, natural vegetation, soils, and land use. Soils are commonly Aridic and Typic Haplustolls in the Mixed Grassland, Moist Mixed Grassland and Aspen Parkland Ecoregions and Molic Haplocryalfs in the Boreal Transition, MidBoreal Upland, and Peace Lowland Ecoregions (Clayton et al., 1977). Despite covering a vast geographic area with a range of grassland and forest soils, crop production on the Canadian Prairies has not been highly diversified. Historically, the area has been dominated by spring cereal production with fallow being a common part of the rotation. On the Canadian Prairies in 2001, there were 10.9 million ha of spring wheat (Triticum aestivum L.), 4.7 million ha of spring barley (Hordeum vulgare L.), and 3.9 million ha of spring canola (Brassica napus L. and B. rapa L.) (Anonymous, 2001).